PB1 ratio Flashcards
Which is the most significant agent formed in the phagolysosome for the elimination of microorganisms?
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1 point
Hypochlorite ions
Proteolytic enzymes
Superoxides
Hydrogen ions
The phagolysosome is the acidic compartment formed when a phagosome (which contains engulfed microorganisms) fuses with a lysosome (which contains digestive enzymes and antimicrobial agents). The most significant agent formed in the phagolysosome for the elimination of microorganisms is hypochlorite ions (HOCl).
Hypochlorite ions are generated from hydrogen peroxide (H2O2) by the enzyme myeloperoxidase in the presence of chloride ions (Cl−). Hypochlorite is highly toxic to bacteria and helps in the killing and digestion of the engulfed microorganisms.
Adverse effects of massive transfusion, except:
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1 point
2,3-DPG depletion
None of the above
Citrate toxicity and hypercalcemia
Hypothermia
Citrate toxicity and hypercalcemia
A unit of packed RBCs is split using the open system. One of the half units is used. What may be done with the second half unit?
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1 point
Must be issued within 24 hours
Must be irradiated
Must retain the original expiration date.
Must be issued within 48 hours
When a unit of packed red blood cells (RBCs) is split using the open system, the second half unit must be issued within 24 hours. This is due to the risk of contamination when the unit is opened and exposed to the environment.
Open system refers to the procedure where the blood bag is opened to divide the unit into smaller portions, increasing the risk of bacterial contamination. As a result, once the bag is opened, it must be used quickly to prevent potential infections.
The 24-hour limit is recommended by regulatory bodies (e.g., AABB) for blood that has been split in the open system, regardless of the original expiration date of the blood unit.
Blood needs to be prepared for intrauterine transfusion of a fetus with severe HDFN. The red blood cell unit selected is compatible with the mother’s serum and has been leukoreduced. An additional step that must be taken before transfusion is to:
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1 point
Irradiate the RBCs before infusion.
Test the RBC unit with the neonate’s eluate
Check that the RBC group is consistent with the mothers
Add pooled platelets and fresh-frozen plasma
Intrauterine transfusion (IUT) is performed when a fetus has severe Hemolytic Disease of the Fetus and Newborn (HDFN), typically caused by Rh incompatibility or other antibody-mediated conditions. Irradiation of red blood cells is an essential step for preventing graft-versus-host disease (GVHD) in the fetus, which could otherwise occur due to the transfusion of lymphocytes present in the blood.
Key details:
Irradiation is used to inactivate any remaining lymphocytes that could attack the recipient’s tissues (in this case, the fetus), reducing the risk of GVHD.
Leukoreduction has already been done to reduce the number of white blood cells in the unit, but irradiation is still required as an additional step.
A whole-blood donor currently on clopidogrel (Plavix) is precluded from donating which product?
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1 point
Cryoprecipitate
Red blood cells
Platelets
FFP
Clopidogrel (Plavix) is an antiplatelet medication that inhibits platelet aggregation, reducing the risk of blood clotting. Since platelets are essential for clotting, clopidogrel interferes with platelet function. For this reason, a donor who is on clopidogrel is typically precluded from donating platelets because the platelets collected from such a donor would be dysfunctional and ineffective for transfusion purposes.
What is the characteristic of class I MHC molecules?
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1 point
Able to bind whole proteins
Consists of one alpha and one beta chain
Coded for by DR, DP, and DQ genes
Bind peptides made within the cell
Class I MHC (Major Histocompatibility Complex) molecules are important for presenting endogenous peptides (peptides derived from proteins synthesized within the cell) to CD8+ T cells. These molecules are expressed on the surface of most nucleated cells and play a crucial role in immune surveillance by presenting antigens to cytotoxic T cells.
Characteristics of Class I MHC molecules:
Bind peptides made within the cell: Class I MHC molecules typically present peptides that are derived from proteins inside the cell, such as viral proteins or abnormal proteins from cancer cells. These peptides are processed by the proteasome, transported to the endoplasmic reticulum, and then loaded onto class I MHC molecules for presentation on the cell surface.
A patient in septic shock caused by a gram-negative bacterial infection exhibits the following symptoms: high fever, very low blood pressure, and disseminated intravascular coagulation. Which cytokine is the most likely contributor to these symptoms?
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1 point
IFN-a
ILs
IFN-beta
TNF
In septic shock, especially due to a gram-negative bacterial infection, the immune response is triggered by endotoxins (lipopolysaccharides, LPS) released from the bacteria. These endotoxins activate immune cells, which release various cytokines, including TNF.
TNF is a key pro-inflammatory cytokine that plays a significant role in the systemic inflammatory response in sepsis. It is responsible for many of the symptoms observed in septic shock, including:
High fever: TNF induces fever by acting on the hypothalamus.
Very low blood pressure: TNF can cause vasodilation, contributing to hypotension, a hallmark of septic shock.
Disseminated intravascular coagulation (DIC): TNF can activate coagulation pathways, leading to DIC, which involves the formation of small blood clots throughout the circulatory system.
The skin is a major component of the external protection of the body. The following are its attributes to first line of natural defense, except:
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1 point
Acidic pH
Langerhan’s cells
Normal bacterial flora
Hair
Attributes of the skin’s first line of defense:
Acidic pH: The skin has an acidic pH (around 4.5 to 5.5), which helps inhibit the growth of many pathogens and supports the skin’s microbiome.
Langerhans cells: These are dendritic cells found in the epidermis of the skin. They play a key role in immune surveillance and act as antigen-presenting cells to initiate an immune response when necessary.
Normal bacterial flora: The skin is home to a variety of non-pathogenic bacteria that form a natural microbiome. These bacteria outcompete pathogenic microbes and help protect the skin from infections.
Hair: While hair serves several functions such as warmth and protection (e.g., for the scalp), it is not directly part of the first line of defense like the other listed features. Hair does not directly contribute to the immune defense against pathogens.
Thus, while hair has certain protective roles, it is not a direct contributor to the skin’s first line of immune defense compared to factors like acidic pH, Langerhans cells, and normal bacterial flora.
A 42-year old man of average body mass has a history of chronic anemia requiring transfusion support. Two units of RBCs are transfused. If the pre-transfusion hemoglobin was 7.0 g/aL (70g/L), the expected posttransfusion hemoglobin concentration should be:
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1 point
9.0 g/dL
11 g/dL
8.0 g/dL
10.0 g/dL
Pre-transfusion hemoglobin: 7.0 g/dL
The patient receives 2 units of RBCs.
Expected hemoglobin increase per unit transfused: 1 g/dL per unit.
So, after transfusing 2 units of RBCs, the expected increase in hemoglobin would be:
7.0 g/dL + 2 g/dL = 9.0 g/dL.
Which of the following is/are true about the Lewis blood group system?
1. Le gene is found in chromosome 9 and codes for fucosyltransferase enzyme.
2. Le antigens are not produced by RBCs but are passively adsorbed from the plasma.
3. The true Lewis phenotype is Le (a+b+).
4. Its expression is affected by the presence or absence of Lewis and Secretor genes.
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1 point
1,2,4
2 and 4
1 and 2
2,3,4
1,2,4
Incorrect. The true Le phenotype is Le(a−b−). The Le(a+b+) phenotype is actually a rare, transient condition seen in certain individuals, but it’s not considered the “true” or typical phenotype. Most individuals are either Le(a−b−), Le(a+b−), or Le(a−b+).
Which of the following conditions are detected in DAT
1. HDN 2. HTR 3. AIHA 4. Donor incompatibility
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1 point
2,3,4
1,2,3
3 and 4
1,2,3,4
HDN (Hemolytic Disease of the Newborn):
Detected in DAT. In HDN, maternal antibodies (often IgG) cross the placenta and bind to the fetal red blood cells, causing hemolysis. The DAT will be positive in the newborn, as it detects the antibodies bound to fetal RBCs.
HTR (Hemolytic Transfusion Reaction):
Detected in DAT. In hemolytic transfusion reactions, antibodies from the recipient react with the transfused red blood cells, leading to their destruction. A positive DAT will show the presence of antibodies bound to the transfused RBCs.
AIHA (Autoimmune Hemolytic Anemia):
Detected in DAT. In AIHA, the body produces antibodies against its own red blood cells. A positive DAT will detect these autoantibodies bound to RBCs.
Donor Incompatibility:
Not typically detected in DAT. Donor incompatibility would typically be detected through other methods such as crossmatching, not through the DAT. The DAT is more relevant to detecting the presence of antibodies already bound to RBCs, rather than issues with donor-recipient compatibility.
Summary:
Blood is drawn from a patient for serological tests for a viral disease at the time of onset and again 4 weeks later. The results of the tests are considered diagnostic if the:
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1 point
First antibody is 4x the second
Second antibody titer is at least 4x in the first
First and second antibody titers are equal
First antibody titer is 2x the second
When diagnosing viral infections, particularly acute infections, seroconversion (the development of detectable antibodies) or a significant rise in antibody titers is key for diagnosis.
Two serum samples are typically collected: one at the onset of symptoms and another 4 weeks later. A fourfold increase (at least 4 times) in the antibody titer from the first to the second sample is generally considered diagnostic of a recent infection.
A fourfold rise indicates an immune response to the infection, meaning that the body has mounted an immune response over the course of the infection, which is a hallmark of seroconversion.
An ASO titer and a streptozyme test are performed on a patients serum. The ASO titer is negative, the streptozyme test is positive, and both the positive and negative controls react appropriately. What can you conclude from these test results?
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1 point
The ASO is falsely negative
The patient has scarlet fever
The patient has not had a previous streptococcal infection
The patient has an antibody to a streptococcal exoenzyme other than streptolysin O
ASO titer (Antistreptolysin O titer) tests for antibodies against streptolysin O, a toxin produced by Group A Streptococcus.
Streptozyme test is a screening test that detects antibodies to several different streptococcal exoenzymes, including streptolysin O, hyaluronidase, deoxyribonuclease B (DNase B), and others.
Given that:
The ASO titer is negative, meaning there is no detectable antibody against streptolysin O.
The streptozyme test is positive, indicating that the patient has antibodies against one or more other streptococcal exoenzymes (such as DNase, hyaluronidase, etc.), but not necessarily streptolysin O.
Thus, the most likely conclusion is that the patient has an antibody to a streptococcal exoenzyme other than streptolysin O, which can still indicate a past streptococcal infection but without the presence of antibodies to streptolysin O.
A 53-year old woman donates blood at her place of employment. She weighs 150 lb and has a hemoglobin of 13 g/dL. She is currently on warfarin and vitamin B12. Is she an acceptable donor?
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1 point
Yes
No, her hemoglobin is too low
No, she is on warfarin
Yes, for red cells only
Yes, for red cells only
Selective IgA deficiency is the most common congenital immunodeficiency. Individuals with transient hypogammaglobulinemia lack circulating mature CD19+ B cells.
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1 point
Only the first statement is correct
Only the second statement is correct
Both statements are correct
Both statements are incorrect
“Selective IgA deficiency is the most common congenital immunodeficiency.”
Correct. Selective IgA deficiency is indeed the most common primary immunodeficiency. It is characterized by a deficiency or absence of IgA (Immunoglobulin A) in the serum and mucosal secretions. Although most individuals with IgA deficiency are asymptomatic, some may experience recurrent infections, particularly in the respiratory and gastrointestinal tracts.
“Individuals with transient hypogammaglobulinemia lack circulating mature CD19+ B cells.”
Incorrect. Transient hypogammaglobulinemia (often seen in infants) involves a temporary low level of immunoglobulins (IgG, IgA, IgM), but it does not specifically result from a lack of mature CD19+ B cells. Rather, the issue in transient hypogammaglobulinemia is typically related to delayed maturation of the immune system during infancy, and CD19+ B cells are usually present, although their ability to produce antibodies may be impaired temporarily.
Which of the following reactions would one expect to see when working with a specimen believed to be a Bombay phenotype?
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1 point
Patient’s cells + A1 and B cells = no agglutination
Patient’s cells + Ulex europeaus = no agglutination
Patient’s cells + group O donor RBCs = no agglutination
Patient’s cells + Ulex europeaus = agglutination
Patient’s cells + Ulex europeaus = no agglutination
In HDFN, when the bone marrow fails to produce enough RBCs, erythropoiesis is increased in the spleen and liver. These organs enlarged (hepatosplenomegaly), resulting in portal hypertension, and hepatocellular damage.
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1 point
Both statements are incorrect
Only the first statement is correct.
Both statements are correct
Only the second statement is correct.
“In HDFN, when the bone marrow fails to produce enough RBCs, erythropoiesis is increased in the spleen and liver.”
Correct. In Hemolytic Disease of the Fetus and Newborn (HDFN), the destruction of red blood cells (hemolysis) leads to anemia. As the bone marrow struggles to keep up with the need for red blood cells, extramedullary erythropoiesis (the production of red blood cells outside the bone marrow) can occur in other organs, such as the spleen and liver. This compensatory process helps to increase the production of red blood cells to mitigate the anemia.
“These organs enlarged (hepatosplenomegaly), resulting in portal hypertension, and hepatocellular damage.”
Correct. As the spleen and liver enlarge due to increased erythropoiesis, they can cause hepatosplenomegaly (enlargement of both organs). The increased size and activity of these organs can lead to portal hypertension (increased blood pressure in the portal venous system) and hepatocellular damage (damage to liver cells), both of which are associated with severe cases of HDFN, particularly in hydrops fetalis or when the disease is left untreated.
The following antibodies in blood group systems are cited as naturally occurring, except:
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1 point
Anti-D
Anti-P1
Anti-AB
Anti-M and Anti-N
Anti-D:
Not naturally occurring. Anti-D is an antibody that targets the Rh (D) antigen on red blood cells. It is not naturally occurring; instead, it typically develops after exposure to Rh-positive red blood cells, such as through pregnancy (in Rh-negative women carrying an Rh-positive fetus) or transfusion.
A patient’s blood type is AB-negative, but there are no AB-negative red blood cell units available. What donor units could be selected?
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1 point
B-positive
All of the above
O-positive
A-negative
A-negative
AB-negative blood type:
The patient has both A and B antigens on their RBCs and no Rh (D) antigen.
The patient does not have anti-A or anti-B antibodies in their plasma, so they can receive RBCs from any donor with A, B, or O blood types.
However, the Rh factor matters: Since the patient is Rh-negative, they should only receive Rh-negative blood to avoid sensitization to Rh-positive RBCs.
Screening cells and major crossmatch are positive on IS only, and the autocontrol is negative. Identify the problem.
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1 point
Cold alloantibody
Antibody mixture
Cold autoantibody
Abnormal protein
Positive screening cells and crossmatch on immediate spin (IS):
A reaction at IS indicates the presence of an antibody that is IgM and reacts at colder temperatures (room temperature or below).
Negative autocontrol:
A negative autocontrol means that the patient’s own red blood cells are not being attacked by the antibody. This suggests the antibody is targeting foreign antigens rather than self-antigens.
Possible causes:
Cold alloantibody: An alloantibody (produced against antigens the patient lacks) that reacts at colder temperatures fits this scenario perfectly.
Examples include antibodies against antigens like I, M, P1, or Lea/Leb.
Identify the type of precipitation test: Antigen is placed on the well and electrophoresed. Antibody is placed on trough parallel to separated proteins, and gradually diffuses into the gel.
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1 point
Rocket immunoelectrophoresis
Immunoelectrophoresis
Radial immunodiffusion
Immunofixation electrophoresis
Immunoelectrophoresis is a two-step technique combining electrophoresis and immunodiffusion to identify and characterize proteins (antigens) in a sample:
Electrophoresis:
The antigen (e.g., serum proteins) is placed in a well and separated by electrophoresis based on charge and size.
Immunodiffusion:
Antibody is placed in a trough parallel to the separated proteins.
The antibody diffuses into the gel and interacts with the separated antigens, forming precipitation arcs where antigen-antibody complexes are formed.
After a needle prick injury, Hepatitis B Ig has been injected to medical technologist. What type of immunity is described?
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1 point
Natural passive
Artificial passive
Artificial active
Natural active
Artificial passive immunity involves the administration of pre-formed antibodies (e.g., immunoglobulins) to provide immediate protection against an infection or toxin.
In this case, Hepatitis B immunoglobulin (HBIG) contains pre-formed antibodies that provide immediate, short-term immunity to the medical technologist after potential exposure to Hepatitis B.
Which transfusion reaction presents with fever, maculopapular rash, watery diarrhea, abnormal liver function, and pancytopenia?
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1 point
Transfusion-associated sepsis
Transfusion-related acute lung injury
Transfusion-associated allergic reaction
Transfusion-associated graft-versus-host disease
Transfusion-associated graft-versus-host disease (TA-GvHD) is a rare but fatal complication of transfusion. It occurs when viable donor lymphocytes attack the recipient’s tissues.
The hallmark clinical features include:
Fever
Maculopapular rash
Watery diarrhea
Abnormal liver function
Pancytopenia (due to bone marrow failure caused by donor lymphocyte attack).
Six units are crossmatched. Five units are compatible, one unit is incompatible, and the recipient’s antibody screen is negative. Identify the problem:
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1 point
Patient may have an abnormal protein
Patient may have an alloantibody to a high-frequency antigen
Donor may have high-frequency antigen
Donor unit may have positive DAT
Donor unit may have positive DAT
The problem is with the donor’s blood, not the recipient’s. The donor unit might have antibodies stuck to its red blood cells, causing the crossmatch to fail, even though the patient’s antibody screen is negative.
Which of the following is/are true about the Rh blood group system?
1. Rh antibodies are primarily IgG class.
2. Rh antibodies are associated with HDFN.
3. Rh antigens are simple sugars.
4. Rh antigens are inherited as autosomal recessive alleles.
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1 point
1 and 3
1,2,3,4
1,2,3
1 and 2
The correct answer is: 1 and 2.
Explanation:
Rh antibodies are primarily IgG class:
True. Rh antibodies, such as anti-D, are primarily of the IgG class. These antibodies are capable of crossing the placenta and causing hemolytic disease of the fetus and newborn (HDFN).
Rh antibodies are associated with HDFN:
True. Rh antibodies, especially anti-D, are the most common cause of hemolytic disease of the fetus and newborn (HDFN), which occurs when an Rh-negative mother is exposed to Rh-positive fetal blood, leading to antibody production against Rh antigens.
Rh antigens are simple sugars:
False. Rh antigens are proteins, not simple sugars. The Rh antigens (such as D, C, c, E, e) are part of a protein complex on the red blood cell membrane, and they are not carbohydrates.
Rh antigens are inherited as autosomal recessive alleles:
False. Rh antigens are inherited as autosomal dominant alleles. The presence of the D antigen (which determines Rh positivity) is dominant over its absence.
Conclusion:
Which of the following is the correct order of events that lead to HDFN?
1. Placental passage of maternal IgG anti-D
2. Maternal antibody formed against paternally inherited D-antigen
3. Hemolysis of fetal RBCs
4. Hemorrhage of D-positive fetal RBCs into D-negative mother
5. Next D-positive pregnancy
6. Maternal antibody attaches to fetal RBCs
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1 point
2,5,1,3,6,4
4,2,5,1,6,3
2,6,5,4,3,1
4,2,5,6,3,1
4, 2, 5, 1, 6, 3
Here’s why:
4. Hemorrhage of D-positive fetal RBCs into D-negative mother: In the first pregnancy, if the fetus is Rh-positive and the mother is Rh-negative, some fetal red blood cells (RBCs) may enter the maternal circulation (often during delivery).
- Maternal antibody formed against paternally inherited D-antigen: The mother’s immune system recognizes the Rh-positive fetal RBCs as foreign, and the mother begins to produce anti-D antibodies in response to the Rh-positive cells.
- Next D-positive pregnancy: In a subsequent pregnancy, if the fetus is again Rh-positive, the mother already has anti-D antibodies from the previous pregnancy.
- Placental passage of maternal IgG anti-D: During the second pregnancy, the maternal IgG anti-D antibodies can cross the placenta and reach the fetal circulation.
- Maternal antibody attaches to fetal RBCs: The maternal antibodies attach to the Rh-positive fetal red blood cells, marking them for destruction.
- Hemolysis of fetal RBCs: This leads to the destruction (hemolysis) of the fetal RBCs, causing Hemolytic Disease of the Fetus and Newborn (HDFN).
Genotype A1A2 will give rise to the phenotype?
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1 point
A1
A
A3
A2
A1
A unit of whole blood is collected at 10:00 am and stored at 20-24C. What is the last hour platelet concentrate may be made from this unit?
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1 point
8:00 pm
7:00 pm
4:00 pm
6:00 pm
Platelet concentrates are typically prepared from whole blood within 8 hours of collection.
6:00 pm
What substance is detected by RPR and VDRL tests for syphilis?
Anticardiolipin antibody
