2.1 Red Blood Cells Flashcards
What are cytokines? Which ones are important for RBCs?
-Cytokines are small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells.
o Erythropoietin (Epo)
o Interleukins
o Inhibitory cytokines
What is the stimulus and source of erythropoietin?
stimulus: hypoxia
source: kidney
how long does erythropoiesis/ maturation take?
(5-) 7 days
what are the cellular compartments of bone marrow relevant hemopoiesis? how do cells progress between these and where do they go from here?
stem cell compartment >
progenitor cell compartment >
precursor cell compartment >
peripheral blood >
peripheral tissues
what is the progression of cell types in erythropoiesis? At what stage do cells stop dividing and only mature?
rubriblast > prorubricyte > rubricyte > metarubricyte > reticulocyte > erythrocyte
division stops around the rubricyte stage
there are other cell names that could be added to this list
what is the rbc lifespan of cows, horses, dogs, and cats?
cow: 160d
horse: 145d
dog: 110d
cat: 70d
Where are red blood cells phagocyosed mainly, and by what?
macrophages remove RBCs in the spleen
what species is it more common to see anisocytosis?
bovine
what species has pale staining platelets?
horses
In what domestic species is it normal for RBCs to have central pallor?
dogs
How do we prepare blood for a CBC and what is measured?
-Store blood in lavender top tube with anti-coagulant (EDTA)
RBC indices:
-MCV: average size of RBCs; microcytic, normocytic, macrocytic
-MCH: hemoglobin per RBC; uncommonly used
-MCHC: hemoglobin/ unit volume; hypochromic (increased central pallor - iron limitation), normochromic, hyperchromic
-rubricytes: immature RBC
Thrombocyte indices:
-MPV: average size of platelets; shift platelets are large and immature
Leukocyte differentials
Anisocytosis
What can we use to detect total plasma protein?
hematocrit tube > refractometer
what do different colours of hematocrit tubes signify?
normal - clear
lipidemia - white
hemoglobinemia - red. free hemoglobin present (more dominant than bilirubin). likely due to IV hemolysis
bilirubinemia - yellow. product of RBC breakdown, could be due to EV hemolytic disease or liver disease. Horses naturally have more bilirubin in their plasma.
what part of a blood smear should we look at to see parasites?
feathered edge
what might give us an artificially low platelet count from a machine? What species is this important for?
platelet clumps at the feathered edge. common in cats
what is auto-agglutination? What should we consider when we see it?
-Antigen-antibody complexes on the RBC surface cross-linking/binding to each other
-Presents in a test tube as stippling of red cells, like bunches of grapes on the smear
-Consider: immune mediated pathogenesis
what is rouleaux? When, where do we see it and what does it mean?
-line of connected
-Usually an artifact – especially in horses and cats
-Uncommon in dogs and ruminants
>When seen in dogs it may indicate that there is an increase in proteins – inflammatory globulins, APPs. Look at biochem panel to assess.
what is the saline dilution test and what is it used for?
-Take a drop of blood and 4 drops of saline, then look at it under a microscope
Rouleaux → dispersal of RBCs
Agglutination → persistent RBC clumps
what is polychromasia and when do we see it?
-Due to increased presence of darker staining immature RBCs – polychromatophils
-Bigger, bluer cells – Wright’s stain
-Released by bone marrow in response to decreased oxygen carrying capacity
-Limited in healthy animals
-Consider: regenerative bone marrow response
-not really seen in horse regenerative response < cow < dogs < cats
what are reticulocytes and when do we see them?
-Bigger cells with residual RNA clumping in a reticular pattern
-Same as polychromatophils but stained with New Methylene Blue & Wright’s
-Consider: regenerative bone marrow response
what is hypochromasia? When do we see it?
-More challenging to identify in dogs
-Consider: iron deficiency
i.e., dog with chronic blood loss entering stage of iron deficiency, impairing RBC production, causing pale RBCs to be released from the bone marrow
what is basophilic stippling? When might we see it?
with wright’s stain
-consider Pb toxicity
what are poikilocytes? When do we see them?
-General change in RBC morphology (size/shape) – many types
-Commonly seen in fragile iron deficient erythrocytes
what is crenation and when do we see it?
-Spikey projections around RBC due to slow drying
-Could hide other features of the cell
-Could be pathologic but usually artifact
what are acanthocytes and when do we see them?
-Long, irregular projections on RBCs due to abnormal composition of RBC membranes (classically have little ‘beads’ on the end of projections)
-Consider: liver/spleen disease when abundant
what are spherocytes and when do we see them? How are they created?
-Small dense cell with no central pallor (easier to identify in dogs)
-Aren’t counted in RDW because they have the same volume as RBCs
-Consider: Immune Mediated Hemolytic Anemia (IMHA) or transfused red cells
-Created when macrophages selectively target the antibody-antigen complex on the RBC, after removal of that portion of the membrane in the spleen, the cell reseals more densely > less Hb
-During transfusion, blood gets added from a bag that could’ve caused morphologic changes due to the fluid or anticoagulant
what is a schistocyte and when do we see them?
Fragmentation of RBCs
-Caused by shearing of RBCs by fibrin in circulation
-Form of hemolysis
-Consider: Disseminated Intravascular Coagulation (DIC)
what is a microcyte and when might we see one?
-Small RBCs
-Consider: Disseminated Intravascular Coagulation (DIC)
what types of inclusions can we see in RBCs?
-parasites
-bacteria
-heinz bodies
-howell-jolly bodies
-nucleated RBCs
what do bacteria look like in RBCs? What test should we follow up with if we detect this?
tiny blue structures on the surface or edge of the cell
-can be hard to detect because they often look like stain precipitate
-follow up with a PCR test
what are heinz bodies? How can we best see them? When do they appear?
-Single projection on the periphery of an RBC
>Areas of denatured hemoglobin
>Better seen with NMB stain
-Somewhat normal in cats because of their unique spleen
>Concerning in anemic cats
-Consider: oxidative damage/hemolysis (and anemia)
>i.e., drugs, chemicals, toxins, acetaminophen in cats, onion/garlic in dogs, Zn toxicity from coins, Cu toxicity in sheep
What are Howell-Jolly bodies? When do we see them and what do they mean?
-Nuclear remnant that was not ejected during differentiation
-Usually removed by the spleen, but can be normal in cats
-Non-specific pathologic indicator
what are rubricytes? Where should they be? When might we find them in circulation?
-Immature, nucleated RBCs that should be in bone marrow
-Present in certain disease circumstances
>i.e., extramedullary hematopoiesis, 1˚ bone marrow disease
What are target cells? What do they mean?
-A blip of hemoglobin in the center of a canine RBC
-Consider: liver disease/neoplasia when abundant
>Otherwise, non-specific
What are eccentrocytes? When might we see them?
-RBC with peripheral white sections
-Clearing of hemoglobin on the periphery of the cell
-Consider: oxidative damage
What are ghost RBCs? When might we see them? What else might we see along with them?
-White round cell marks
-Consider: intravascular hemolysis
>Plasma would likely be red due to free Hb (hemoglobinemia)
what are dacrocytes and what should we consider if we see them?
-Tear drop shaped cells
-Consider: myelofibrosis and other BM issues
>Check the bone marrow!
when do we see protein crescents on a blood smear?
if there is increased protein in the blood
Which values will be low in a case of anemia?
RBC: presents on blood smear as more space between the RBCs
Hgb
HCT: used to classify severity
What RBC issues can anemia be due to?
- Decreased RBC production
-At the level of the BM
-Note that current cells will remain for the duration of their lifespan - Increased RBC loss
-Cells removed from circulation by hemorrhage or hemolysis
what are seven possible things that could lead to anemia?
- renal failure
- hemolysis
- endocrine
- neoplasia
- inflammation
- blood loss
- iron deficiency
How do we assess an anemia? What tools can we use to gather evidence?
History – acute or chronic?
PE
CBC
Reticulocyte count – regen.?
Total serum/plasma protein
How do we characterize an anemia?
- Severity
-Defining severity is subjective and comes with experience based on HCT
>Sometimes based on other analytes too! - MCV
- MCHC
- Regenerative/non-regenerative
Broadly, what are the possible causes of regenerative anemia? How will these show in protein levels?
hemolysis or internal hemorrhage - normal or high protein
>note that protein can also be influenced by inflammation and dehydration (appear higher)
external hemorrhage - low protein
broadly, what are the possible causes of non-regenerative anemia? What are the characteristics of each?
marrow disorder
1˚
-Disease arising in the bone marrow itself
-Directly involved in the disease process
-Multiple cytopenias
2˚
-A systemic disease impacting RBC production in the BM
-Selective red cell depression
what are the tell-tale signs of a regenerative anemia?
-Increased polychromasia/reticulocytes
>increased anisocytosis; RDW
>increased MCV; macrocytosis
>decreased MCHC; hypochromasia
-Increased neutrophils, platelets
>Can have leukopenias still
-Rubricytes cannot be the sole indicator of regenerative anemia
>If there is no polychromasia, another explanation is required
>Increased rubricyte count requires a corrected WBC count due to it counting nucleated cells
>WBC – rubricyte count = corrected WBC
what are the tell-tale signs of hemorrhage? What differences might we see between single site vs multiple site?
- Anemia
- Hypoproteinemia (with sufficient external blood loss)
- Reticulocytosis – bone marrow shouldn’t be impaired
- Hypochromia (if chronic and external)
>Due to loss of iron over time, leading to decreased hemoglobin
Single sites = local problems
-i.e., trauma, neoplasm
Multiple sites = platelet and clotting factor issues
-i.e., GI bleeding, blood loss in urine, hematomas
