Transfusion Immunology

Question 1

Chromosome 9 has the ________ gene which adds terminal sugars onto _____ of RBCs for blood typing.

Answer 1

Chromosome 9 has a glycosyltransferase gene that adds sugars onto glycoproteins of RBCs.

Question 2

A allele enzyme adds ______; B allele adds ______ and O allele adds _____.

Answer 2

A allele = N-acetylgalactosamine;
B allele = terminal galactose;
O allele = has no activity, only H-core protein

Question 3

What kind of donor serum can a recipient of Type A accept from a plasma transfusion?

Answer 3

Donor must be Type A or AB (must not have anti-A antibodies).

Question 4

What kind of donor serum can a recipient of Type B accept from a plasma transfusion?

Answer 4

Donor must be Type B or AB (cannot have anti-B antibodies).

Question 5

What kind of donor serum can a recipient of Type AB accept from a plasma transfusion?

Answer 5

Donor must be AB (must lack both A and B antibodies).

Question 6

What kind of donor serum can a recipient of Type O accept from a plasma transfusion?

Answer 6

Donor can be A, B, AB or O (recipients lacks antigens, so there is no issue with a reaction here).

Question 7

Incorrect transfusions will cause antibodies to react against donor blood which can be seen as antigens. What type of hypersensitivity reaction is this?

Answer 7

Type II (cytotoxic) hypersensitivity reaction involves the hemolysis of donor RBC’s

Question 8

What 3 events occur during intravascular RBC lysis?

Answer 8

1. ABs coat the RBC
2. Complement will upregulate from the IgMs.
3. Liberated Hb can be toxic to the kidneys.

Question 9

Describe what can happen in the event of disseminated intravascular coagulation (DIC).

Answer 9

Localized clotting in the circulation can occur with an unfavorable reaction. This can use up clotting factors which can lead to bleeding out.

Question 10

What antibody reacts to Rh factor and what would they do in the event of an unfavorable transfusion?

Answer 10

IgG’s react to Rh factor. They will opsonize RBCs for phagocytosis in the spleen

Question 11

Define Rh Incompatibility Disease. Why is this significant if it occurs during pregnancy?

Answer 11

This is a condition in which the mother is Rh-, the father is Rh + and the fetus is Rh +. It is a dangerous situation that can lead to Erythroblastosis fetalis of newborns where the mother’s IgGs can cross the placental barrier to attack the fetal RBCs.

Question 12

What treatment can be given to an expectant mother to desensitize the Rh Incompatibility?

Answer 12

Rhogam, an immune globulin, can be given at the 3rd trimester and within 72 hours of the 1st birth to destroy fetal RBCs in maternal circulation before they initiate an immune response.

Question 13

A recipient for whole blood transfusion is blood type AB. The compatible donor plasma should lack:

Answer 13

Donor plasma should LACK anti-A and anti-B antibodies so as not to react with recipient RBCs.

Question 14

A recipient for whole blood transfusion is blood type O. The compatible donor plasma can have:

Answer 14

Anti-A, anti-B or both antibodies types. Type O’s can receive plasma from all blood types (O, A, B or AB).

Question 15

Anti-ABO antibodies involve the immunoglobulin ____ which causes _____ hemolysis of antigenic RBCs.

Answer 15

IgM = activates complement + destroys RBCs in blood stream via intravascular hemolysis.
These are great at Agglutination and are useful for blood-typing.

Question 16

Anti-Rh antibodies involve the immunoglobulin _____, which causes _____ hemolysis of incompatible RBCs.

Answer 16

IgG = coats RBCs to be destroyed by macrophages in the liver or spleen via extravascular hemolysis.

Question 17

How do anti-Fab’s differ from anti-Fc’s?

Answer 17

Anti-Fab’s are more specific to a certain antibody because they bind to the VARIABLE region. Whereas, Anti-Fc’s are isotype specific, binding to the CONSTANT region.

Question 18

Define Direct Coomb’s test (binding-type, step-wise process, *significance).

Answer 18

DAT is used to detect cell-bound ABs. You take suspect RBCs, add Coomb’s reagent (anti-IgG) and observe agglutination of RBCs with suspected antibodies bound to them.
This is used to diagnose autoimmune hemolytic anemia.

Question 19

The Coomb’s reagent is usually immunoglobulin _____ because it is great at agglutinating RBCs. This binds to the ___ region of the suspect antibody.

Answer 19

DAT = IgG that binds to the Fc (constant) region of antibodies.

Question 20

Define Indirect Coomb’s test (binding-type, step-wise process, *significance).

Answer 20

IDAT = detects RBC IgG in plasma. This involves taking the patient’s serum, adding stock RBCs to it, adding anti-IgG AB and looking for agglutination.
This is useful for detecting Rh sensitization of a mother or fetus.

Question 21

Direct Coomb’s is to ______ disease, as indirect Coomb’s is to ______ disease.

Answer 21

DAT = autoimmune hemolytic anemia;
IDAT = Rh sensitization (risk of erythroblastosis fetalis).

Question 22

Describe the clinical features of Multiple Myeloma.

Answer 22

This is a malignancy that produces way too many ABs. Tumors are present in the bone and can be seen as punched out areas in the CT scan of a patient’s skull. Bence-Jones proteins can be seen as light chains in the urine.

Question 23

In monoclonal gammopathy, which protein type can be seen at high levels using electrophoresis?

Answer 23

ABs of gamma-type protein (y-band) can be seen at high levels.

Question 24

What are the highest immunoglobulin isotypes in multiple myeloma?

Answer 24

IgG (60%) IgA (25%) or rarely IgE.

Question 25

Describe Waldenstrom’s macroglobulinemia.

Answer 25

Appears as less mature B-cells that secrete IgM. Blood from affected patients is viscous and there is an increased risk of osteoporosis.

Question 26

Describe Heavy-chain disease, pertaining to monoclonal gammopathy.

Answer 26

Only heavy chain of IgG is secreted.

Question 27

Describe Light-chain disease, pertaining to monoclonal gammopathy.

Answer 27

Only the light chain is secreted and can get into the urine (called Bence Jones Proteins.

Question 28

Describe the process of immunofixation.

Answer 28

Immunofixation determines which isotype is elevated by applying the patient’s serum with unknown anti-body to several cellulose acetate strips. This enables you to compare the antibody serum levels to that of control.

Question 29

Describe at least 3 clinical features that are presented in an unfavorable transfusion reaction.

Answer 29

1. Hemolysis
2. Renal failure
   Free hemoglobin in blood/urine
3. Decreased hematocrit and high bilirubin

Question 30

What Coomb’s test can detect complement and why?

Answer 30

Direct Coomb’s test because complement requires a cellular surface to be activated.