Exam 2 Flashcards
Blood components
• red blood cells
• plasma (fresh, frozen plasma, FFP)
• platelets
• cryoprecipitate
• granulocytes (limited usage-neutropenia)
• stem cell harvests
Blood processing
Whole blood—> Packed RBCs , platelet rich plasma—>
RBC: Leukoreduction, washing, irradiation, freezing
PRP: plt concentrate or FFP—> cryo, plasma derivative
Apheresis
the removal of blood plasma from the body by the withdrawal of blood, its separation into plasma and cells, and the reintroduction of the cells, used especially to remove antibodies in treating autoimmune diseases.
• infuse with saline while removing blood to take out the RBCs
Antibodies against ABO are:
Naturally occurring (the only ones). If you have B type blood, do you have A antigens on your cells
Intravascular
Fix and bind complement, causing rapid, systemic response
Extravascular
Bind to surface of RBC. RBC is removed by the reticuloendothelial system.
Intravascular hemolysis causes:
- Increased free hemoglobin, hemoglobinemia
- Hemoglobinuria (blood in the urine)
- Increased bilirubin, jaundice.
Antibodies that cause intravascular hemolysis
• ABO
• Kidd, Jka and Jkb
Rare:
• li
• Vel
• p system
• Gerber
Blood group antigens, and their associated membrane structures
• ABO: carbohydrate
• Rh: protein
• Kell: glycoprotein
• Kidd: glycoprotein
• Duffy: glycoprotein
• Lewis: carbohydrate
• MNS: sialoglycoprotein
• P: glycolipid
H substance, and additional A/B
H substance: the baseline backbone of an ABO gene
A: terminal N-acetyl galactose amine added
B: terminal galactose added
O: no additional chain added
What are ABO antibodies?
Naturally occurring IgM antibodies form by six months of age. They are antithetical type (B antibodies form in group A person)
What does IgM do?
Binds and fixes complement, causing intravascular hemolysis (strong, rapid, systemic reaction)
Rh
• complicated system, 48 antigens
• most immunogenic blood group, not naturally occurring
• antibodies are IgG, not IgM
• located on chromosome one
• five important antigens:
1. D= Rh
2-5: C, E, c, e
Rh clinical importance
• immediate and delayed hemolytic transfusion reactions causing EXTRAVASCULAR Hemolysis
• IgG can cross the placenta— anti-Rh/D is given to mom to block the exposure from mom to the baby D antigen
Kidd (Jka, Jkb)
• antibodies, cause severe intravascular hemolysis
• famous for disappearing- antibody titer drops below detection, and is unseen until reaction occurs
Duffy (Fya, Fyb)
• antibodies cause extravascular hemolysis
• receptor for plasmodium vivax (malaria, protective depending on selective pressures)
Compatibility testing
• type and screen:
1. Type: ABO, Rh(D)
2. Screen: does the patient have antibodies against major RBC antigens?
• crossmatch: final test for compatibility
Front type ABO testing
• mix patients red blood cells with unknown antiserum and look for agglutination (testing for antigen on the patients red blood cells)
Back type ABO testing
• mix, patients plasma with known red blood cell and look for agglutination (testing for antibody in the patient’s blood)
Hemagglutination test
• mix RBC with known antibody
• mix B RBC with an anti-A antibody= no agglutination
• mix B RBC with an anti-B antibody= agglutination
• mix B-type plasma with group A RBC= agglutination
• mix B type plasma with Group B RBC= no agglutination (would be self reactive)
Positive screen
Antibody and patients plasma that recognizes a clinically relevant RBC antigen
Volume of a red blood cell unit
• 250–350 mL
• plasma = < 50mL
• 200-250 mg iron
• leukoreduced
The effect of one unit transfusion
• increase hematocrit by 3%
• increase hemoglobin by 1 g/dL
When is RBC infusion indicated?
• anemia: low hematocrit (normal around 36-50%), or hemoglobin level (<7 g/dL)
• symptomatic: tachycardia, or evidence of insufficient oxygen delivery
• neonates and cyanotic heart disease: hemoglobin <13g/dL
Volume of plasma infusion
• 200 -250 mL
• 400 mg fibrinogen
• factor 7: half life of four hours, lose quickly once you start thawing
• dosage: 10-20 mg/kg, two units should increase factor levels by 20- 30%
• AB Plasma is used in emergencies (no antibodies towards A or B)
Transfusion indications of plasma
• INR > 1.8 (plasma is generally ineffective for INR less than 1.8)
• PTT > 45”
• indicated: emergency reversal of warfarin, if vitamin K or prothrombin complex concentrates do not work
Single donor platelet unit (SDP)
• Six whole blood derived units
• 300 mL
• 150 mg fibrinogen
• bump: 1 SDP should increase platelet count to around 25-40,000
Platelet storage
• stored for up to 5 to 7 days at room temperature
• highest risk of bacterial contamination and septic transfusion reaction
Platelet indications
• 5000/ul has been shown to be the minimum required for maintenance of endothelial integrity
Transfuse if :
• < 10,000 for normal patient
• < 20,000 for mucosal bleed
• < 50,000 for active bleeding, surgery, invasive procedure
• < 50,000 for infant less than one month old
• < 100,000 for neuro or ophthalmologic surgery
• if playlist dysfunction due to drugs, or bypass pump
Cryoprecipitate
• cold-insoluble portion of a frozen plasma unit that precipitates when the frozen plasma is thawed between 1–6 C
• 15mL
• 250 mg fibrinogen
• factor 8
• vonWillebrand’s factor
• factor 13
• fibronectin
indication: mainly fibrinogen deficiency, <150mg/dL for active bleeding and <100mg/dL normally
RBC: 1 unit
• increases hemoglobin by 1 g/dL and hematocrit by 3%
• triggers for transfusion: 7 g/dL, stable, non-bleeding, patients OR 8 g/dL patients with greater oxygen demand
Platelets: trigger for transfusion
• 10,000 ul for non-bleeding patients
• 50,000 ul for procedures/ bleeding patients
• 100,000 ul for neurosurgery/ophthalmology
Plasma and cryoprecipitate:
Plasma: transfuse for INR> 1.8
Cryoprecipitate: transfused for
1. Fibrinogen < 150 g/dL in actively bleeding patients
2. Fibrinogen < 100 g/dL in non-bleeding patients
Leukoreduction
• white blood cells contribute to the overall transfusion reactions, and increase the risk of anti-HLA antibodies which can cause rejection of solid organ, transplants, and platelet refractoriness
Irradiation
• lymphocytes in donor bag may recognize recipient (transfused patient) as foreign and mount an immune attack— irradiation disables lymphocytes
• associated lymphocytes can cause transfusion associated graft versus host disease (TA-GVHD) in severely immunocompromise patients— usually fatal
Indications for irradiation
• past current or eminent (two weeks) stem cell transplant
• purine analog drugs in the past 12 months (fludarabine, cladribine, and pentostatin)
• Campath (alemtuzumab)
• congenital, immunodeficiency syndrome (diGeorge, Wiskott-Aldrich, severe combined immunodeficiency, variable, combined immunodeficiency)
• pediatric (all newborns up to six months old, intrauterine transfusions, all pediatric cancer patients)
• oncology— Hodgkin’s lymphoma only
When is irradiation contraindicated?
• if excess potassium is a problem:
1. Compromised cardiac function.
2. Pre-existing hyperkalemia
Washing (saline)
• plasma proteins cause allergic and anaphylactic a transfusion reactions
• washing removes all plasma proteins
• indicated when patients have a history of severe allergic reactions or anaphylaxis
• severely limits the shelf life: RBC= 24 hours, platelets= 4 hours
Volume reduction
• removes excess plasma without washing
• useful for patients with volume overload and congestive heart failure (CHF)
• can help prevent transfusion associated circulatory overload (TACO)
• maybe used with pediatric patients who cannot process volume
• also removes plasma, therefore helps patients with a history of allergic reactions
The signs and symptoms of a transfusion reaction
• fever, chills, rigors
• pain— infusion site, back pain
• respiratory problems
• cardiovascular problems
• cutaneous: itchiness, hives, erythema, Flushing, jaundice, pallor
• GI: nausea, vomiting, diarrhea
• urinary: red urine, hemoglobinuria
• heme: bleeding, oozing, coagulopathy
What do you do if you suspect an acute transfusion reaction?
- Stop the transfusion immediately.
- Keep the IV line open with saline
- report reaction to the blood bank
- Return, unused portion of unit was infusion set to the blood bank.
- Send additional labs— EDTA, red top, urine
What does the blood bank do when receiving word of an acute transfusion reaction?
• clerical check: confirm intended unit was transfuse to intended patient
• repeat ABO blood type and screen for RBC antibodies
• direct antiglobulin test (DAT) to test for antibodies on the RBC
• check serum color (pink – red for hemolysis)
• Gram stain and culture
Allergic transfusion reactions
• 1 to 3% of transfusions
• hypersensitivity to plasma proteins
• mild reactions cause urticaria
• treatment: Benadryl, steroids
• ** mild allergy, and patient response to therapy is the only instance where the transfusion may be restarted
Anaphylactic reactions to transfusions
• 1 in 20,000-50,000
• platelets> plasma> RBC
• more severe reaction: systemic
• symptoms: hypertension, bronchospasm, wheezing, local, edema, anxiety, abdominal distress
• treatment: Trendelenburg, epinephrine, anti-histamines, steroids, beta 2-agonist
Hemolytic transfusion reaction
• acute hemolytic reaction occurs within 4 hours of transfusion (usually immediately)
• due to the presence of preformed antibody ( RBC transfusion= major incompatibility, platelet/plasma transfusion= minor incompatibility)
How does hemolytic transfusion reaction occur?
Antibody coated RBC activate the complement system —> hemolysis (intravascular) —> cytokine storm —> coagulopathy (DIC)
Hemolytic transfusion reaction, signs and symptoms
• fever- most common
• red urine (hemoglobinuria)
• red plasma (free hemoglobin)
• hypotension, shock
• severe flank pain
• chest tightness, and sense of impending doom
• DIC, oozing
• vomiting, diarrhea
Laboratory findings of hemolytic transfusion reaction
• positive DAT
• elevated LDH
• elevated bilirubin
• low haptoglobin
• low fibrinogen
• elevated plasma hemoglobin
Delayed hemolytic transfusion reaction (DHTR)
• typically occurs 5- 14 days— weeks after an RBC transfusion
• formation of a new antibody, especially from the KIDD blood group (kids play hide and seek)
• antibody undetectable on screen prior to transfusion
• signs: unexplained drop in hemoglobin, unexplained rise in unconjugated bilirubin, and positive DAT (RBCs have antibody on their surface)
Febrile, non-hemolytic transfusion reaction
• one of the most commonly reported reactions (1%)
• fevers, chills, rigors
• mechanism: antibodies in recipient plasma to antigens on donor lymphocytes, granulocytes, and platelets. Cytokines present in stored plasma/Supernatant portion of product
• treatment: supportive/symptomatic
• diagnosis of exclusion
Causes of respiratory distress associated with a transfusion
- Transfusion associated circulatory overload (TACO)
- Transfusion related acute lung injury (TRALI)
- Hemolytic transfusion reaction
- transfusion associated sepsis
- Anaphylactic/anaphylactoid reactions
- Coincidental underlying conditions, such as COPD, anxiety, PE, reaction to a medication, or asthma
Transfusion related acute lung injury (TRALI)
• acute onset- within six hours of transfusion
• acute lung injury: hypoxemia, bilateral infiltrates on chest x-ray, no evidence of left atrial hypertension, no other cause for acute lung injury
• previously was the number one cause of transfusion related mortality (is now TACO)
Mechanism of TRALI: immune
• donor has antibodies to recipient human neutrophil antigens (HNA) or HLA on neutrophils
• soluble antibody antigen complex, activate complement —> neutrophil influx —> damage
Mechanism of TRALI: non-immune (two hit hypothesis)
• pre-existing condition, activates neutrophils
• transfused blood has accumulated lipids, that further activate, the already primed neutrophils
Prevention of TRALI
• plasma containing products are more frequently implicated in TRALI
• multiparous and transfused females are the most likely to have an anti-HNA or anti-HLA
• switching to male donor only plasma has significantly reduced rates of TRALI (as well as testing)
Transfusion associated circulatory overload (TACO)
• volume overload from transfusion
• occurs during or within several hours of transfusion
• symptoms: dyspnea, respiratory distress, orthopnea, cyanosis, tachycardia, HTN, rales, jugular venous distention (JVD), S3 on cardiac auscultation, lower extremity edema
• treatment: discontinue transfusion and fluids, give diuretics and supportive measures (O2)
In the incidence of ICU patients, TACO occurred in
1:356
- Increase risk and very young, very old, renal failure, and chronic anemia
Post infusion purpura
• acute severe onset of thrombocytopenia (platelets < 10,000)
• 3 to 10 days post transfusion
• amnestic response to a platelet antigen, exposure causes removal of both transfused and self platelets— can occur from any type of transfusion (rare)
Transfusion associated graft versus host disease (TAGVHD)
• engraftment of donor lymphocytes
• rash, severe, diarrhea, liver abnormalities, pancytopenia (bone marrow aplasia)
• 4-30 days post transfusion
• almost always fatal !!
What prevents TA- GVHD?
Irradiation (removal/ inhibition of donor lymphocytes)
What contributes to blood safety?
- Volunteer donations
- Selection of healthy donors
- Universal donor health questionnaire
- Mini exam (vitals, hemoglobin, check arms for needle tracks)
- Donor testing
Transfusion associated sepsis
• 1 in 5000 platelets have been confirmed positive culture for bacteria (usually a subclinical amount)
• more common with a platelet transfusion: because they are stored at room temperature
• symptoms: fever, hypotension, shock, nausea, vomiting, respiratory symptoms, coagulopathy
Estimated risk for transfusion transmission of viruses
- HBV (1 in 205,000-488,000)
- HCV (1 in 1,935,000)
- HIV (1 in 2,135,000)
What viruses most commonly get transfused?
- west Nile virus
- CMV
Which parasites most commonly get transfused?
• Chagas disease- Trypanosoma Cruzi
• malaria- plasmodium species
• Babesia
PRION: variant CJD
What are some other complications of a transfusion?
• hypothermia
• citrate toxicity
• coagulopathy (dilutional)
• electrolyte imbalances (excess potassium)
• iron overload
• air embolism (very rare)
Microcytic anemias include:
• RBCs< 80 MCV
• low iron: iron deficiency anemia
• normal/high iron: ACD/thalassemia
Normocytic anemias include:
• RBCs 80-100 MCV
• reticulocyte count:
1. High: hemolytic anemia or blood loss
2. Low: acute blood loss, aplastic anemia, early IDA, anemia of renal disease, myelopthisic anemia
Macrocytic anemias include:
• RBCs > 100 MCV
• normal B12/folate: reticulocyte count for normocytic anemia
• low B12/folate: megaloblastic anemia
Iron deficiency anemia
• most common overall anemia, worldwide
• symptoms: pallor, fatigue, dyspnea on exertion, headache, syncope
• signs: pallor, spooning of the nails (koilonychia)
• when associated with dysphasia/esophageal webs consider: plummer-Vinsen syndrome, Paterson-Kelly syndrome, sideropenic dysphasia
What causes iron deficiency anemia?
• low, dietary intake: infants, bed exclusively on milk, unbalanced food
• increase demands: pregnancy, infancy
• malabsorption: celiac, disease, post-gastrectomy, duodenum problems
• intravascular hemolysis (think: microangiopathic hemolytic anemia, and proximal nocturnal hemoglobinuria)
Methods of estimating iron
- Serum iron levels (120 µg/dL in men and 100 µg/dL in women)
- TIBC 300 to 350 µg/dL, indirectly measures transferrin
- Serum ferritin levels
- Assessment of BM Fe (reliable, but invasive)
What regulates absorption of iron from the diet?
Hepcidin
Laboratory findings of iron deficiency anemia
• low hemoglobin
• low PCV (packed cell volume)
• low red cell count
• RDW (anisocytosis) increased
• low MCV (<80)
• low MCHC and MCH
• decreased percent saturation of iron
• decrees ferritin
• INCREASED TIBC (total iron binding capacity)
Poikilocytosis
an increase in abnormal red blood cells of any shape that makes up 10% or more of the total population. Poikilocytes can be flat, elongated, teardrop-shaped, crescent-shaped, sickle-shaped, or can have pointy or thorn-like projections, or may have other abnormal features.
IDA bone marrow
• cellularity: increased
• erythroid hyperplasia
• micro-normoblastic maturation
• bone marrow iron: (Prussian blue reaction) reduced or absent
Treatment of iron deficiency anemia
• administer iron— oral ferrous sulfate
• caution: GI side effects and stool turns black
• how do you assess the response to treatment? — reticulocyte response in 7 to 10 days
Anemia of chronic disease (ACD)
• chronic infections, inflammation, malignancy, and anemia of renal disease
• pathogenesis: IFN, TNF, IL1-beta and IL6 block iron transfer from macrophage store —> RBC (prevent kidney release of erythropoietin)
• cells are mildly microcytic and hypochromic
• typically resistant iron therapy
What is the most common form of anemia in hospitalized patients?
Anemia of chronic disease— because of suppression of erythropoiesis by systemic inflammation
Common causes of anemia of chronic disease (ACD)
• chronic osteomyelitis
• bacterial endocarditis
• TB/lung abscess
• chronic inflammation (rheumatoid arthritis)
• neoplasms: Hodgkin’s lymphoma, breast, and lung cancer
Pathogenesis of ACD
• increased hepatic hepcidin synthesis—> increased plasma hepcidin —> blocks transfer of iron to erythropoiesis precursors by down regulating ferroportin in macrophages
• ferritin is increased, transferrin is reduced, serum iron is low
Differences in clinical features of ACD versus IDA
• ACD: Decreased TIBC, increased storage iron in bone marrow, serum ferritin
• ACD and IDA same: hypochromic and microcytic, low serum iron
Chronic renal failure anemia
• decreased EPO
• decreased ACD
• normocytic anemia
• BURR cells
• prolonged bleeding time: defect in platelet aggregation, reversible with dialysis
Basis of anemia of CRF:
• Reduce production of erythropoietin
• CRF caused by: diabetes, chronic glomerulonephritis, chronic pyelonephritis
• lab findings: increased serum, BUN, and creatinine, low reticulocyte count, burr cells
• treatment: recombinant erythropoietin
Sideroblastic anemias
• group of anemias with a defect in heme synthesis in the mitochondria (accumulation)
• leads to ring sideroblast
What can cause a defect and heme synthesis within the mitochondria of developing RBCs in the bone marrow?
- Chronic alcoholism.
- Vitamin B6, pyridoxine deficiency
- Lead (Pb) poisoning
Two major types of sideroblastic anemia
- Congenital: X-linked, mitochondrial
- Acquired: myelodysplastic syndrome, copper or vitamin B6 deficiency, lead poisoning, alcoholism, drugs, porphyria
Laboratory findings of sideroblastic anemia
• moderate to severe anemia
• hypochromic, microcytic/normocytic, dimorphic
• erythroid hyperplasia in bone marrow, macronormoblastic erythropoiesis
• almost complete saturation of TIBC
• presence of ringed sideroblasts must be present for diagnosis
Lead poisoning
• most common in children, ages 1 to 5
• may occur in utero, because it crosses the placenta
• causes: pica (eating, lead based paint), pottery painting, factory workers, radiator repair mechanics, air contamination
What enzymes does lead denature?
- Ferrochelatase: iron, cannot bind with protoporphyrin to form heme
- ALA dehydratase: causes an increase in Delta-ALA
- Ribonuclease: ribosomes cannot be degraded and persist in the RBC- results in coarse basophilic stippling
Clinical findings in children with lead poisoning
• abdominal colic with constipation
• encephalopathy: cerebral edema, papilledema, demyelination
• learning disabilities
• growth retardation: Pb gets deposited in the epiphysis of growing bone
Clinical findings in adults with lead poisoning
• peripheral neuropathy: foot drop, claw hand, wrist drop
• nephrotoxic damage to proximal renal tubules
• lead line in the gums (Burton’s)
• reduced RBC survival time
Diagnosis and treatment of lead poisoning
• increased whole blood and urine lead levels
• treatment: chelation therapy; succimer, dimercaprol, ethylene diamine tetra acetic acid (EDTA)
Laboratory findings of sideroblastic anemia
• increased serum iron, iron saturation, ferritin
• normal to decreased MCV
• decreased TIBC
• ringed sideroblast in bone marrow aspirate
• course basophilic stippling of RBCs due to persistence of ribosomes
Anaplastic anemia
• normocytic anemia affecting the hematopoietic stem cells—> malfunction of myeloid stem cells (granulopoiesis, erythropoiesis, thrombopoiesis)
• causes anemia, neutropenia, and thrombocytopenia
• can be caused by: chloramphenicol, chemotherapeutic agents, benzene, ionizing radiation, biological agents (Parvo B19)
What happens in aplastic anemia?
• multipotent myeloid stem cells are suppressed, leading to bone marrow failure and pancytopenia
• causes autoreactive, T cells, and defects in telomerase
Lab findings in aplastic anemia
• normal lymphoid stem cells
• decreased cellularity in the bone marrow
• increased Adipose tissue in the bone marrow
• Pancytopenia on peripheral blood smear
Clinical features of aplastic anemia
• fever (infection associated with neutropenia)
• bleeding (thrombocytopenia)
• fatigue (anemia)
• does not cause splenomegaly
• lymphocytes are present in the bone marrow and peripheral blood
Pure red cell aplasia
• a rare form of marrow failure, characterized by the absence of red cell precursors in the bone marrow
• resulting in decreased RBC production, granulocytic and platelet precursors are normal
• causes: Parvo B19, thymoma (myasthenia gravis)
• the only manifestation is anemia
Myelophthisic anemia
• caused by space occupying lesions that distorts the bone marrow
• result in decreased productivity
• diseases that infiltrate, the bone marrow are known as myelophthisic processes
• causes: metastatic cancer, granulomas, tuberculosis, marrow fibrosis
• peripheral smear will show: Leukoerythroblastic picture (immature red and white blood cell in the peripheral blood)
Hemolytic anemias
• premature destruction— hemolysis
• jaundice, gall stones
• marked increase in reticulocytes
• extravascular: within the macrophages of spleen and liver
• intravascular: within the circulation (blood vessels)
Hemolytic anemias cause:
• decreased red cell lifespan
• compensatory increase in erythropoiesis —> increased reticulocytes and polychromatophilia in peripheral blood
• retention of degraded red cell products (including iron— secondary hemosiderosis)
• pigmented gallstones
Extravascular hemolysis
• premature destruction of red cells within phagocytes
• reduce deformability of red cells (abnormal shape)
• RBCs containing inclusions
• big three: anemia, splenomegaly, jaundice
Intravascular hemolysis
• mechanical damage
• enzyme deficiency
• complement mediated lysis
• hemoglobinemia, hemoglobinuria, hemosiderinuria
• plasma haptoglobin is reduced
• serum LDH is elevated
What has unconjugated hyperbilirubinemia, acholuric jaundice, increased urine urobilinogen, and acute tubular necrosis?
Intravascular hemolysis
Hemolytic, anemia classification
Acquired/external injury
• physical
• drugs (alpha-methyldopa, cephalosporins, ibuprofen)
• parasite/infections: malaria, septicemia (DIC)
Congenital/internal defects
• defective membrane: spherocytic anemia
• defective Hgb: SCA, thalassemia
• deficient enzyme: G6PD deficiency
Urine color for intravascular versus extravascular hemolysis
• intravascular: cola colored
• extravascular: dark urine/high colored urine (orange)
Red blood cells are normocytic and normochromic in all hemolytic anemia, except:
Thalassemia
Spherocytes
• hereditary Spherocytosis
• immune hemolytic anemia
• ABO incompatibility
Schistocytes (broken red blood cells)
• MAHA
• HUS
• TTP
• DIC
• prosthetic heart valve
Target cells
• thalassemia
• alcoholic liver disease
• splenectomy
Dacryocyte (teardrop cell)
• myelophthisic anemia
• myelofibrosis
Sickle cell
• sickle cell anemia
Elliptocytes
• hereditary elliptocytosis
Acanthocyte
• irregular spicules on surface, seen in abetalipoproteinemia
Echinocyte (burr cell)
• uremia, kidney disease
Bite cell
• RBC with bites of cytoplasm being removed by splenic macrophages
• seen in G6PD deficiency
Bone findings in severe hemolytic anemia
• due to compensatory increase in erythropoiesis leading to bone distortions
• chipmunk face
• frontal bossing (skull malformation)
• crewcut Skull x-ray
• hyperplasia
Iron generates oxidative stress through:
non-enzymatic Fenton reaction ( H2O2 + Fe2+ –> OH w/free radical + OH- + Fe3+)
Iron homeostasis is controlled at the level of:
Iron uptake via Hepcidin, there is no regulated iron excretion system
what is the greatest use of iron in the body?
Erythropoiesis
Iron distribution in the body:
- hemoglobin iron (F:28 mg/kg, M: 32 mg/kg)
- Storage iron in the liver (F: 5-6, M: 10-12)
- Myoglobin iron (F: 4, M: 5)
How is dietary iron uptaken?
- By DMT1 in intestinal epithelial cells
- exported to the blood at the basolateral side through ferroportin (and oxidation of ferric iron by hephaestin occurs)
- Hepcidin produced in the liver regulates the uptake of dietary iron by blocking Ferroportin
What turns Ferric iron into Ferrous in the lumen of the gut?
- Brush border ferreductase (DcytB)
- it can then be brought into the cytoplasm via DMT1
What oxidizes ferrous iron to ferric iron in order to be bound to and transported by transferrin?
- Hephaestin, a copper dependent enzyme
What, produced in the liver, binds and inactivates ferroportin?
Hepcidin
What is the intracellular storage of iron?
- Ferritin, a storage of hundreds of atoms of ferric iron. Stored as a mineral crystal
- If there is high ferritin in the serum, that indicates iron excess
Regulation of iron uptake in the duodenal epithelial cells:
- Happens at the level of translation
1. high iron –> binds IRP1/2 –> cannot bind mRNA at the 5’ end –> transcription (FTH, FTL, ferroportin, HIF2-alpha, and ALAS2 are expressed)
2. High iron –> binds IRP 1/2 –> cannot bind mRNA at the 3’ end –> TFR1 and DMT1 mRNA degraded –> uptake from diet is decreased
3. low iron –> cannot bind IRP1/2 –> IRP 1/2 binds mRNA at the 5’ end –> NO transcription (FTH, FTL, ferroportin, HIF2-alpha, and ALAS2 are repressed)
4. low iron –> cannot bing IRP 1/2 –> IRP 1/2 binds at mRNA at the 3’ end –> TFR1 and DMT1 mRNA stabilized –> increased uptake from the diet
Transferrin saturation
TFS: used to estimate iron status.
Normal range: 15-55%, it is DECREASED in iron deficiency, but INCREASED in hemolytic anemia and hemochromatosis
EQN: TFS = 100 x Serum iron / total iron binding capacity
Transferrin receptors on the surface of erythroid precursors bind:
iron-bound transferrin (holo-transferrin) –> stimulated endocytosis –> ferric iron becomes ferrous iron via STEAP3 –> transported out of the endosome by DMT1 –> endosome fuses with plasma membrane to release free transferrin (APO-transferrin)
– this is called the Transferrin cycle
How is heme tightly bound to hemoglobin?
- interactions between propionate (polar), arginine, and histidine
- methyl and vinyl groups (hydrophobic) on heme interact with hydrophobic amino acids
- iron atom is stabilized by 6 interactions: four nitrogens in heme, and two nitrogens from histidines (distal and proximal) in the globin chain
Oxygen binding displaces:
- distal histidine and the iron pulls the proximal histidine towards the heme plane. This changes the shape of the entire molecule
Oxygen binding of one subunit of hemoglobin increases:
the affinity of other subunits for oxygen. this allosteric effect gives hemoglobin a SIGMOIDAL curve and allows it to accept oxygen in the lungs and donate it in the tissues
What happens to RBCs when they age (hit their lifespan)?
- they get taken up by macrophages and destroyed (primarily in the spleen)
What enzyme breaks the heme ring and releases ferrous iron in the macrophage?
Heme oxidase (HO-1)
How is hemoglobin released into the circulation from intravascular hemolysis recovered?
it binds to haptoglobin. The haptoglobin/hemoglobin complex is taken up by receptor mediated endocytosis
What uptakes free heme to be endocytosed?
Hemopexin
How is iron stored?
- Ferritin (liver, spleen, skeletal muscle, marrow)
- Hemosiderin (macrophages)
- excess iron is exported through a similar mechanism as duodenal epithelial cells. The Iron is oxidized by CERULOPLASMIN, a homolog of hephaestin
Hepatocytes uptake iron via:
Transferrin receptor endocytosis. (they can also take up heme bound iron, and free iron via ferreductase and a divalent metal transporter to carry it into the cell)
What organ is critical for maintaining iron homeostasis?
- LIVER via Hepcidin encoded by the HAMP gene produced in high iron conditions
What diverse signals regulate Hepcidin?
- Erythropoiesis (increase in erythropoiesis creates a hepcidin decrease because you need iron to create RBCs)
- Iron status (Regulated by HFE, TFR1/2, via ERK and SMAD. Increased iron activates and increases hepcidin)
- Inflammation (IL6 –> JAK/STAT –> increases hepcidin)
What is erythropoietin?
- a hormone produced in the kidneys in response to low oxygen (hypoxia) that stimulates the production of reticulocytes, therefore inhibits hepcidin
Ferrous iron is a cofactor for:
Prolyl hydroxylase (PHD2). HIF-2 is regulated post-transcriptionally by 5’ iron response elements and IRE-BP
Other uses of iron:
- ribonucleotide reductase in nucleotide synthesis
- ATPase ABCE1 required for translation
- primases for DNA replication and transcription
(all iron-dependent)
Iron deficiency anemia specific signs:
-microcytic, hypochromic
- Pagophagia (compulsion to chew on ice)
-Koilonychia (spoon nails)
- Akathisia (restless leg)
- Blue sclera
What are some things that would cause an increase demand for iron, and therefore a deficiency?
- blood loss
- growth
- pregnancy
In a healthy person, iron will be found in:
- mostly erythroid cells
- macrophages
- liver
As iron is depleted, where is the loss seen first?
- macrophages and liver storage decrease first
- then the erythrocyte iron (leading to microcytic anemia)
Iron refractory iron deficiency results from
- overproduction of hepcidin
- the most common mutation is from the BMPR complex, the Matripase-2 (TMPRSS6) is mutated
Maltripase-2
a protease in the BMPR complex that propagates the transferrin receptor signal. Mutations in TMPRSS6 cause very high hepcidin expression resulting in iron refractory iron deficiency anemia
Anemia of chronic disease
- driven by IL6 inflammation (increased hepcidin expression to block pathogen from using iron to reproduce and spread
- iron does not get absorbed, and gets sequestered in the liver and macrophages
- (IL6 –> IL6R –> JAK1 –> STAT3 –> onto promoter –> increased hepcidin)
Hemochromatosis
- results from disorders in the hepcidin production or ferroportin function
- HFE hemochromatosis is most common hereditary form of iron overload, where hepcidin is not produced and iron intake is unregulated
The most common cause of hereditary hemochromatosis is:
- the loss of function mutations in HFE, a protein required for transferrin receptor signaling
- the negative feedback through hepcidin is lost, and iron uptake is uncontrolled
How do we define anemia?
- reduced absolute number of circulating RBCs
- reduction in one or more of the major red blood cell measurements (Hgb concentration, Hematocrit, RBC count)
Reticulocyte index
RI <2 is hypoproliferative
RI >2 is hyperproliferative
DAT (Direct antiglobulin test) - Coombs test
- positive is consistent with warm autoimmune hemolytic anemia
- Hemolytic anemia will also have decreased macrocytic erythrocytes with marked anisocytosis, moderate polychromasia, and circulating nucleated RBCs on a peripheral smear
Microcytic anemia characteristics
- MCV < 80
- Low MCH
- decreased hemoglobin content
- hypochromic
- Iron deficiency
What is the one test to determine between IDA and ACKD?
Ferritin!
- Ferritin low = IDA
- Ferritin high = ACKD
Thalassemia minor
- Hgb low
- Microcytic
- RBC count is normal/increased
- asymptomatic
- iron studies are normal
- Hgb analysis is diagnostic
Aplastic Anemia
- Life threatening bone marrow failure
- Pancytopenia associated with bone marrow hypoplasia/aplasia
Microcytic anemia differential
- Iron deficiency (IDA)
- Thalessemia
- Anemia of chronic disease
- lead poisoning
- zinc deficiency
- copper deficiency
Normocytic anemia differential
- Systemic disorders
- anemia of chronic disease/ chronic kidney disease
- acute blood loss
- early iron deficiency
- bone marrow suppression
Macrocytic anemia differential
- Megaloblastic anemia (B12 deficiency or Folate deficiency)
- liver disease
- alcoholism
- hypothyroidism
- myelodysplastic syndrome
- drugs
- multiple myeloma
Mononucleosis causes:
- fever (101-103), usually low grade
- Fatigue
- sore throat
- swollen lymph nodes (posterior cervical)
- swollen tonsils, difficulty swallowing
- pharyngitis
- presence of atypical lymphocytes on peripheral blood smear
Labs for mononucleosis
- High WBC
- high lymphocytes
- low neutrophils
- high monocytes
- blood serum positive for IgM and IgG against EBV capsid antigen
Downey-McKinlay cells
- Atypical lymphocytes, reactive and large due to antigenic stimulation
- associated with viral infection but also *Addison’s disease and *Rheumatoid arthritis
What pathogens typically cause Downey-McKinlay cells?
- EBV
- CMV
- T. palladium
- Group B strep
- HCV
- Hantavirus
Heterophile antibody:
Heterophile antibodies are antibodies induced by external antigens (heterophile antigens).
Some cross-react with self-antigens. For example, in rheumatic fever, antibodies against group A streptococcal cell walls can also react with (and thus damage) human heart tissues. These are considered heterophile antibodies.
Why are heterophile antibodies created in EBV infections?
- Heterophile antibodies are produced in response to antigens produced during EBV IM (EBV heterophile antigens or Paul–Bunnell antigens)
- Serum of patients with infectious mononucleosis contain heterophile anti-Paul- Bunnell (PB) antibodies to erythrocytes of numerous mammalian species
How do you test for heterophile antibodies?
Monospot: Serum from the patient is added to a test card which contains either test red blood cells or latex beads with adsorbed red cell antigen. If heterophile antibodies are present in the patient’s serum, there is agglutination which has a speckled appearance on the test card.
Diagnosis of EBV/mononucleosis
- Presence of IgM to viral capsid proteins
- appearance of non-specific, heterophile antibodies with the presence of atypical lymphocytes
- Screen for HIV because acute HIV and EBV infections can have similar presentations
Immune system control of EBV/mono infection is largely:
T-cell mediated. It requires CD8+ T cells
What does EBV look like?
Virus, dsDNA, class 1, linear genome, icosahedral nucleocapsid, enveloped, gamma herpes virus (HHV-4)
The virion contains:
- Envelope proteins
- Outer tegument
- inner tegument
- major capsid protein
- triplex
- portal vertex
- nucleocapsid
EBV replicates in:
the oral epithelium
- infectious virus in the saliva
- lymphocytes in tonsils are directly affected–> massive proliferation
- latent infection in memory B cells
- linear genome converts to circular episome (B cells immortalized)
- CELLULAR IMMUNITY (CD8+ T cells)
EBV receptor is:
CD21 found on B cells
LMP1 and LMP2
- Potent oncogenes
- LMP1 triggers CD40:CD40L -like binding response in the B cell without interaction with any helper T cells to encourage survival and growth
- LMP2a mimics intracellular B cell signaling (like Ab:Ag binding and activation of IP3 and DAG) leading to cell survival and proliferation
EBV is linked to what malignancies?
- Burkitt’s lymphoma
- nasopharyngeal carcinoma
- Lymphoproliferative disease
Burkitt’s Lymphoma gene alteration
- Translocation t(8;14) (q24; q32) in 75% of cases: reciprocal translocation involving the c-myc gene (chromosome 8) and heavy-chain Ig locus (chromosome 14) → overactivation of c-myc proto-oncogene → activation of transcription
Burkitt’s Lymphoma
Burkitt lymphoma is a type of non-Hodgkin lymphoma (NHL). NHL is a cancer of the lymphatic system. It develops when the body makes abnormal B lymphocytes. Commonly develops with co-infection of EBV and malaria
What does the histology look like for Burkitt’s Lymphoma?
Starry sky pattern: Microscopic finding that resembles a starry sky. Tingible body macrophages (containing many phagocytized tumor cells- white cells) are scattered diffusely within a sheet of uniform neoplastic cells (lymphocytes- dark sky)
- Many vacuoles are seen
X-linked lymphoproliferative disease
- EBV infection leads to rapid fulminant hepatitis and hemophagocytic syndrome (fatal or near fatal infections)
- Caused by a malfunction in signaling lymphocyte activation molecule-associated protein (SAP) OR by malfunction in X-like inhibitor of apoptosis (XIAP)
Hodgkin Lymphoma
a type of cancer that affects the lymphatic system, which is part of the body’s germ-fighting immune system. In Hodgkin’s lymphoma, white blood cells called lymphocytes grow out of control, causing swollen lymph nodes and growths throughout the body
Reed-Sternberg cell
Reed-Sternberg cells are large, abnormal lymphocytes that may contain more than one nucleus. These cells are found in people with Hodgkin lymphoma.
What viruses cause aplastic anemia?
- EBV
- CMV
- Hepatitis
- Parvo B19
- HIV
Hairy leukoplakia
- a disease of the mucosa from immunodeficiency leading to unchecked EBV lytic replication, causing white patches on your tongue. It is associated with Epstein-Barr virus (EBV/ HHV4). It occurs most commonly in people infected with HIV.
Nasopharyngeal cancer from EBV
The association of EBV with epithelial cell tumors, specifically nasopharyngeal carcinoma (NPC) and EBV-positive gastric carcinoma (EBV-GC) is currently thought to be caused by the aberrant establishment of virus latency in epithelial cells that display premalignant genetic changes.
What is the most common familial hemolytic anemia in the world?
Sickle cell anemia
- in malaria endemic parts of Africa
- 8% if African Americans are heterozygous for HbS
What is sickle cell anemia?
-autosomal recessive disorder
- intrinsic defect with predominantly extravascular hemolysis
- homozygotes: all HbA replaced by HbS
- heterozygotes: only half HbA replaced with HbS
- HbS is a mutation in the beta-globin gene that creates the sickle
How is HbS created?
a mutation in the beta-globin gene leading to a substitution of valine for glutamic acid at the 6th amino acid residue
Pathway of sickle cell anemia
red cells containing HbS –> passage through microcirculation of spleen –> low O2 tension–> Sickling occurs –> cell pass through circulation with good O2 tension (other organs) –> desickling –> various cycles of sickling an desickling –> cell membrane affected and change in membrane permeability –> irreversible sickling –>sickled RBCs
Morphology of homozygous sickle cell disease
(HbSS) in peripheral smears, elongated, spindled, or boat-shaped irreversibly sickled red cells
Consequences of sickling in homozygous Sickle cell disease
- severe hemolytic anemia, lifespan of RBC only 20 days
- Microvascular obstructions (vaso-occlusive crisis)
- increased expression of adhesion molecules on sickled cells
- sluggish blood flow, increased transit time for red cells
- repeated sickling damages the RBC membrane, making them adhere to the endothelium
Splenic changes and complications due to vaso-occlusion (Sickle cell)
- functional asplenia, nonfunctional spleen
- Howell Jolly bodies (nucleus remnants)
- autosplenectomy- small and fibrosed spleen due to repeated episodes of infarction
Symptoms of sickle cell
- retinopathy
- blindness
- Lung: pneumonia, infarcts, acute chest syndrome
- iron overload, heart and liver
- pigment: gallstones
- stroke
- atrophic spleen
- Kidney problems
- avascular necrosis of femoral head
- osteomyelitis
- skin ulcers
Fetal hemoglobin
- HbF high at birth and persists until 5-6 months of age, prevents sickling
- has a high affinity for oxygen, therefore preventing sickling
- increased by hydroxyurea
What increases the synthesis of fetal hemoglobin?
- Hydroxyurea
Homozygous sickle cell disease symptoms
- vascular congestion, thrombosis, and infarction in bones, liver. kidney, retina, brain, and skin
- Dactylitis (sausage fingers/toes) from infarction to metacarpal bones, aseptic necrosis
- renal papillary necrosis
-recurrent leg ulcers - hemosiderosis and pigment gallstones
- avascular necrosis of femoral head
- proliferative retinopathy–> blindness
- end-stage renal failure
- Priapism, penile fibrosis and ED
What is acute chest syndrome?
• most common cause of death in young adults with sickle cell disease
• vaso-occlusion in pulmonary microcirculation
• presents with chest pain, dyspnea, and lung infiltrates
• precipitated by pneumonia, bone infarct with fat embolism
Stroke
• most common cause of death in children with sickle cell disease (2-5 years old)
• recurrence rate of 70%
Aplastic crisis
• associated mostly with parvovirus
• no reticulocytes in peripheral blood
• bone marrow does not produce enough blood cells
Sequestration crisis
• rapid splenic enlargement with entrapment of sickled, RBCs and blood
• reticulocytes are present
• these individuals are prone to infections such as S. Pneumonia, and salmonella osteomyelitis
How can you produce sickle cells in a sickle cell trait Patient?
Introduced in vitro by exposing cells to market hypoxia (sodium metabisulfite)
What are the confirmatory test of sickle cell disease?
• Hb electrophoresis
1. HbSS - disease, HbS 90 to 95%, no HbA
2. HbAS - trait, HbS 40-45% and HbA 55-60%
Prenatal diagnosis of sickle cell disease
Analyzing fetal DNA obtained by amniocentesis, or biopsy of chorionic villi to detect the point mutation
What are the treatments of sickle cell disease?
• penicillin prophylaxis to prevent pneumococcal infections
• pneumococcal vaccine, folic acid supplementation
• hydroxyurea to reduce pain crisis, and lessen the anemia by increasing the red cell level of HbF
• allogeneic BMT
Hereditary spherocytosis
• intrinsic defect in membrane, RBCs become spheroid and less deformable—> vulnerable to splenic, sequestration and destruction (extravascular hemolysis)
Prevalence of hereditary spherocytosis
• autosomal dominant inheritance pattern
• prevalence is highest in northern Europe, most common intracorpuscular inherited hemolytic anemia in whites
What causes hereditary Spherocytosis?
• Autosomal, dominant defect involving spectrin (MC) in the RBC membrane
• loss of membrane fragments and decrease in RBC surface membrane—> transformation of spherocytes
• other mutations: ankyrin, band 3, or band 4.2
Why does spherocytosis continue to occur after splenectomy?
Because spherocytes are created by faulty skeletal problem of the RBC
Pathway of primary abnormality in the cytoskeletal proteins leading to spherocytosis
Mutation of ankyrin gene —> abnormal ankyrin protein —> deficiency of spectrin assembly —> decreased membrane stability
What is the special test confirming presence of spherocytes?
• osmotic, fragility test
Clinical features of spherocytosis
- Chronic hemolytic anemia
- Plenty of spherocytes (more than in WAHA)
- Massive splenomegaly
- cholecystitis, cholelithiasis
- Aplastic, megaloblastic, hemolytic crisis (coombs)
Hereditary elliptocytosis
• autosomal dominant
• mutation in spectrin/band 4.1
• intrinsic defect with extravascular hemolysis
• mild hemolytic anemia
• 25% elliptocytes in peripheral blood
Thalassemia
• globin deficiency
• defective globin chain synthesis
• alpha thal: decrease in alpha-Hb —> beta forms abnormal tetramers —> Heinz bodies, basophilic stippling
Minor thalassemia
• normal/mild, anemia, micro, hypo, target cells
Major thalassemia
• severe hemolytic anemia (transfusion, dependent)
Alpha thalassemia
• African-American, Southeast Asian
• deletion of genes for alpha globin chain (4 genes on chromosome 16
• no alpha chain— in utero death
• extravascular
• P smear: microcytic hypochromic RBCs with many target cells
• HbH, Hb Barts
Beta thalassemia
• African-Americans and Mediterranean descent
• mutation in beta globin gene
• presents after six months, after HbF is gone
• extravascular
• microcytic hyperchromic, RBCs with many target cells
• electrophoresis: reduced HbA, increased HbF & HbA2
Mechanism of anemia in beta thalassemia
• damaged erythroid precursors die by apoptosis
• ineffective erythropoiesis, associated with increased absorption of dietary iron leading to iron overload
• shortened RBC lifespan, due to extravascular hemolysis
• relative folate deficiency
Beta thalassemia major
• ineffective erythropoiesis and hemolysis
• impaired bone growth, skeletal deformities
• expanded marrow fills intramedullary space and invading the bony cortex
• hyperplasia of mononuclear cells, splenomegaly, hepatomegaly, lymphadenopathy
• growth retardation, and cachexia
• severe hemosiderosis
Mediterranean anemia/Cooley anemia
• microcytosis
• hypochromia
• poikilocytosis
• anisocytosis
• nucleated red cells (normoblasts)
G6PD deficiency
• most common enzyme deficiency causing homolysis
• intrinsic defect with predominantly intravascular, hemolysis and mild extravascular hemolysis
• x-linked, prevalent in tropical Africa
• G6PD A- : 10% of African-American males in the United States
• G6PD Mediterranean : hemolysis is more severe (G6PD half life is markedly reduced, <10%)
Things that cause G6PD symptoms
• infection
• drugs: antimalarial’s (primaquine), sulfonamides, nitrofurantoin, phenacetin, dapsone, aspirin, vitamin K
• fava beans
G6PD morphology
• Heinz bodies (oxidize, hemoglobin, forming intracellular inclusions)
• bite cells (splenic phagocytes)
Pyruvate kinase deficiency
• autosomal recessive
• intrinsic defect was extravascular hemolysis
• no pyruvate, increased 2,3-DPG
• hemolytic, anemia, with jaundice at birth, splenomegaly
Paroxysmal nocturnal hemoglobinuria
• intrinsic defect with **intravascular hemolysis
• x-linked, acquired intracorpuscular defect
• somatic mutation in PIG-A (impaired synthesis of GPI anchor) on myeloid stem cells
• Decay accelerating factor (DAF-CD55)
• glycosyl- phosphatidyl inositol required for fixation of CD55, CD59, C8 binding proteins to sell surfaces
What is affected in proximal nocturnal hemoglobinuria?
• all myeloid lineages are affected (pancytopenia)
• leukocytes are also deficient in protective proteins, but less sensitive to complement mediated lysis
Clinical findings of proximal nocturnal hemoglobinuria
• episodic hemolysis (when compliment is activated by mild acidosis— during sleep)
• hemoglobinuria noted in first morning void
• iron deficiency overtime
• play the destruction predisposes to: thrombosis, by releasing TXA2
• increased risk of AML
Diagnosis of proximal nocturnal hemoglobinuria
• flow cytometry— decreased CD55/CD59 expression on RBCs, WBCs, platelets
Older tests:
• sucrose hemolysis test
• ham acidified serum test
• urine hemosiderin: positive
• peripheral blood: pancytopenia, reticulocytosis
Treatment of proximal nocturnal hemoglobinuria
• corticosteroids
• targeted therapy with antibody (eculizumab) prevents the conversion of C5 to C5a (increases risk for neisseria infections/meningococcal sepsis)
• anticoagulation to prevent thrombosis
• bone marrow transportation
Paroxysmal, cold hemoglobinuria (PCH)
• extrinsic defect with intravascular hemolysis
• transient hemolytic, anemia in children, with measles, months, influenza, chickenpox (also associated with syphilis)
• IgG causes the antibody with bithermal activity (Donath- Landsteiner antibody)
Donath-Landsteiner antibody
• directed against P blood group antigen on RBCs
• add cold temperatures binds to RBCs, and fixes complement— detaches at 37° and activates compliment, causing intravascular hemolysis
• hemolysis, when moving from a cold to warm environment, symptoms resolved on moving back
Clinical features of proximal cold hemoglobinuria
• fevers, rigors, chills
• red to brown urine
• Reynauds phenomenon
• transient hepatosplenomegaly with jaundice
• oliguria and renal failure
Immunohemolytic anemia: warm antibody type (70%)
• primary- idiopathic
• secondary- B cell neoplasm, auto immune, drugs (alpha, methyldopa, penicillin, quinidine)
• most common immune hemolytic, anemia, caused by IgG at 37 degrees
• opsonization of red blood cells by autoantibodies, leading to phagocytosis in the spleen and elsewhere
• positive DAT
• spherocytes and polychromasia
Immunohemolytic, anemia: cold antibody type (30%)
• post infectious
• mycoplasma, EBV, CMV, associated with lymphoproliferative disease
• acute: mycoplasma infection, mononucleosis
• chronic: idiopathic, B cell lymphoid neoplasms)
• low affinity IgM antibodies stop buying to RBC membranes only at temperatures less than 30°
• mediated by antibodies to blood group antigen I or i
• RBCs, phagocytosis by macrophages and spleen and liver— sludging of blood capillaries do the agglutination often producing Reynaud phenomenon
Cold antibody type (IgM) AIHA
• viral infection (mycoplasma, EBV)
• drugs: quinidine, forms immune complex with IgM to complete compliment, mediated lysis
• CLL: IgM Ab against I blood group Ag
Microangiopathic hemolytic anemia
• mechanical Hemolysis from aortic stenosis, defective, cardiac valve prosthesis (causing schistocytes)
Microangiopathic hemolytic anemia
• DIC
• malignant hypertension
• SLE
• TTP
• HUS
• disseminated cancer
Laboratory findings of hemolytic anemia resulting from trauma/mechanical injuries
• schistocytes in peripheral blood
• decrease haptoglobin in serum
• urine hemosiderin
• iron studies: deficiency
• MCV: normocytic
• reticulocyte count >3%
Malaria
• plasmodium falciparum
• Anopheles mosquitoes
• parasites destroy large numbers of infected RBCs, causing intravascular hemolytic anemia
• massive splenomegaly and occasional hepatomegaly
Cerebral malaria
• infection of RBCs with P.falciparum induces positively charged surface knobs which bind to adhesion molecules on activated endothelium
• traps RBCs in post capillary venules, especially cerebral vessels in children
• rapidly, progressive, convulsions, and death usually occur in days to weeks
Blackwater fever
• massive intravascular hemolysis from malaria
• hemoglobinemia
• hemoglobinuria
• jaundice
Vitamin B 12 in propionate metabolism
Propionyl CoA —> methylmalonyl-CoA — B12 —> succinyl CoA
• without B12, you have an accumulation of propionyl CoA which causes demyelination of nerve fibers, and increase urine methylmalonic acid (B12 only, not folate)
What do you find in the peripheral blood smear of a B12 deficiency?
• Hyper segmented neutrophils
• large, misshapen platelets
• morphologic changes in other systems
• MCV > 110
Blood smear, finding in megaloblastic anemia
• oval, macrocytes, pancytopenia —> cell division
• anisopoikilocytosis : hemolysis
• hyper segmented neutrophils: large cells/megaloblast in bone marrow
What causes pernicious, anemia?
Auto immune attack of intrinsic factor in the duodenum/GI system leads to decreased intake of B12
• atrophic gastritis
• associated with: Hashimoto thyroiditis, Addison’s, DM-1
Clinical features of pernicious anemia
• ryles tube aspirate: achlorhydria
• blood: Hypergastrenemia, IF auto antibody
• gastric biopsy: chronic atrophic gastritis
• increased serum, bilirubin, and LDH (increased RBC breakdown)
• Schilling test: absorption corrected by IF
Non-megaloblastic macrocytic, anemia
• macrocytes around rather than oval shaped
• hyper segmented neutrophils NOT present
• leukocytes and platelets are normal
• no glossitis and no neuropathy
• usually alcohol excess, or hypothyroidism
Liver disease associated with alcohol is commonly causative of
• non-megaloblastic macrocytosis without anemia
• round macrocytes and target cells are seen in chronic alcoholism
Granulopoiesis stages
Myeloblast —> promyeloblast —> myelocyte —> metamyelocyte —> band form —> mature neutrophil
Hypersegmented neutrophils
• Larger than normal neutrophils, bands
• blood and bone marrow of patience with vitamin B-12 or folate deficiency
• myelodysplasia
• patient receiving chemotherapy, such as hydroxyurea
Pelger -Huet nucleus (neutrophil)
• neutrophils with bilobed nuclei in the pince-nez conformation
• nuclear Chromatin denser than normal
• presence of hypo segmented neutrophils due to: severe infection, burns, malignancy, chemotherapy, drugs, such as sulfonamides
• reverts back to normal, when causative agent is removed
Neutrophil with toxic granulation
• large
• purple or dark blue, azurophilic granules
• resembling the primary granules of promyelocytes in the cytoplasm of neutrophils, bands, and metamyelocytes
• associated with: severe infection and chemical poisoning
Toxic vacuolation
• vacuoles, representing the site of digestion of the phagocytosed material
• in the cytoplasm of neutrophils and bands
• frequently associated with toxic granulation
Alder-Reilly granules
• large
• purple, or purpleish-black
• coarse
• azurophilic granules (resembling primary granules of promyelocytes)
• seen in cytoplasm of virtually all mature, leukocytes, and occasionally in the precursors
• seen mainly in Alder-Reilley anomaly, and autosomal recessive disorder due to a defect in mucopolysaccharides
May-Hegglin body
• seen in May-Hegglin anomaly
• associate with purpura and bleeding
• giant platelets containing few granules, large basophilic cytoplasmic inclusion bodies in granulocytes resembling Doyle bodies
• mutation in MYH9 gene on a chromosome 22
• no bleeding episodes other than in cases of severe thrombocytopenia
Chediak-Higashi granules
• giant abnormal lysosomes, often round
• red-blue or greenish-gray granules of variable size seen in cytoplasm of leukocytes, and sometimes in normoblasts in patients with CHS
• kill bacteria in neutrophils and monocytes, however process less effective than normal cells, because these neutrophils have impaired locomotion
• recurrent infections result
Dohle body
• single or multiple blue, grayish-blue or greenish inclusions of variable size and shape in cytoplasm of neutrophils, bands, and metamyelocytes
• remnants of free ribosomes or rough endoplasmic reticulum
• scene in association with toxic granules and vacuoles
Auer body (Auer rod)
• pink, or red, round, or rod shaped cytoplasmic inclusions
• scene in immature, granulocytes and monocyte precursors in patients with acute non-lymphocytic leukemia’s
• represent agglomeration of azurophilic granules
• Fagot cell: cell containing multiple Auer rods, clump together in form of a bundle— seen in acute promyelocytic leukemia
Leukocytosis
Idiopathic neutrophilia, increase neutrophils, asymptomatic
Leukopenia
• ethnic, or benign familial neutropenia
• cyclical neutropenia: cyclical variation in white blood cell counts
• Kostmann’s syndrome: congenital agranulocytosis- lack of G-CSF = severe neutropenia and severe infections
• Felty’s syndrome: RA + severe neutropenia
• SCID: absent T lymphocytes
WBC function disorder: CGD
Defective microbicidal function, lazy leukocyte syndrome
Lazy leukocyte syndrome (schwachman syndrome)
• defect in neutrophil chemotaxis and deficient random mobility of neutrophils
• blood neutrophils cannot migrate to the side of tissue injury
• phagocytic, and bacteriocidal activities are normal
• abnormalities in migration, or intrinsic to granulocyte
• alteration, in structure or function of microfilamentous protein of granulocyte membrane leading to altered deformability— excessive, or under rigidity of neutrophils (cannot leave bone marrow)
Most common symptoms of lazy leukocyte syndrome
• 1 to 2 years of age is one complications occur due to infections
• stomatitis
• otitis media
• bronchitis
• recurrent infections in general
Diagnosis of lazy leukocyte syndrome
• recurrent infection, periodontitis, and stomatitis
• TLC low
• ANC as low as 100 to 200
• bone marrow contains normal number of mature neutrophils
Job syndrome
• autosomal, dominant inheritance
• mutation in STAT3 (protein products act as transcription activators)
• T17 helper T cells produce aisle, 17 chemotactic agent for monocytes and neutrophils decreases
• abnormal chemotaxis of neutrophils and monocytes (cold, soft tissue, abscesses and recurrent pneumonia)
• hyper immunoglobulin E syndrome (Hyper IgE)
• red hair, leonine face, chronic eczema, eosinophilia, and increased serum IgE
Neutrophilic leukocytosis
• key finding: toxic changes
• left shift: presence of immature, neutrophils in peripheral blood (>10%)
• toxic granulation: increases in azurophilic granules
• cytoplasmic vacuolation: phagolysosomes indicating presence of phagocytosis
• Leukomoid reaction when severe
What is a leukomoid reaction?
• exaggerative leukocyte response to serious infections, marked increase in WBC count (>30,000-50,000)
• may involve any leukocyte
• if neutrophils are involved, peripheral smear, may show marked shift to the left, resembles the finding seen in CML
What infections may cause a leukomoid reaction?
• perforated acute appendicitis (neutrophils)
• whooping cough (lymphocytes)
• infectious mononucleosis (lymphocytes)
• cutaneous larva migrants (eosinophils)
What is a leukocyte alkaline phosphatase score?
• LAP: seen in leukomoid reaction, present in specific granules- a marker of mature neutrophil
• score is increased in leukomoid reactions
• CML has a low score, since the cells are neoplastic (CML also has positive Ph chromo)
Infectious mononucleosis
• Epstein-Barr virus
• B lymphocytes via CD21 receptors
• CD8+ T cells respond and form atypical lymphocytes (Downey cells)
• classic triad: fever, sore throat, lymphadenopathy, hepatosplenomegaly
• complications: hepatic dysfunction, splenic, rupture, rash, if treated with ampicillin
• Paul Bunnell reaction: Monospot test
• atypical lymphocyte: virocyte
EBV/ mononucleosis proteins
• EBER-1: EBV, viral non-coding RNA
• EBNA-1: EBV nuclear antigen
• LMP-1: EBV CD40 signaling
• LMP-2: EBV BCR signaling (Ab:Ag)
