3.3.2 Immune-mediated Anemia

Question 1

What is responsible for the agglutination of RBCs in the Coombs test?

Answer 1

Ab attachment

Question 2

Differentiate a direct Coomb’s test from an indirect Coomb’s test.

Answer 2

Question 3

Describe what must occur in a direct or indirect Coomb’s test in order to get a positive or negative result.

Answer 3

Question 4

What would you expect to happen in a Coomb’s test where A/B/AB blood is put into serum with Anti-A or Anti-B antibodies?

Answer 4

Question 5

What is the difference b/t cold and warm agglutination? What type of Ig molecule is each most primarly used for?

Answer 5

The temperature, dummy!

Warm: IgG, Cold: IgM

Question 6

For the following conditions, would you use cold or warm agglutination?

Idiopathic, Chronic inflammation, Mycoplasma pneumonia, Neoplasms, B cell lymphoproliferative disorder

Answer 6

Warm: Idiopathic, Chronic inflammation, Neoplasms

Cold: Idiopathic, Mycoplasma pneumonia, B cell lymphoproliferative disorder

Question 7

Which of the following would you NOT expect to generate a positive antiglobulin test?

A.Drug-induced hemolytic anemia

B.Mismatched blood transfusion

C.Systemic lupus erythematosus

D.Paroxysmal nocturnal hemoglobinuria

E.Rheumatoid arthritis

Answer 7

D. Paroxysmal nocturnal hemoglobinuria

Question 8

Which of the following antibody isotypes will most likely bind ABO antigens?

A.IgA

B.IgD

C.IgE

D.IgG

E.IgM

Answer 8

E. IgM

Explanation: Since ABO antigens are carbohydrates, they will elicit a T cell-independet responses. The primary Ab’s produced in a T cell-independent response are IgM. B cells are dependent upon T cells for the induction of class switching

Question 9

What would you expect the results of direct and indirect Coomb’s tests to be in a patient who was given a mismatched transfusion?

Answer 9

Pos/Pos

Question 10

Explain the immunologic process that links the transfusion of mismatched blood to the backache and decrease in blood pressure.

Answer 10

IgM in the serum binding onto the patient’s RBCs leading the the activation of complement. Complement initiates inflammation, which increases vasopermability resulting in a drop in BP.

Question 11

Which of the following antibody isotypes most readily crosses the placenta?

A.IgA

B.IgD

C.IgE

D.IgG

E.IgM

Answer 11

D. IgG

Question 12

Which of the following proteins is responsible for transferring immunoglobulin across the placenta?

A.FcεRI

B.FcγRII

C.FcμR

D.FcRn

E.Poly-Ig receptor

Answer 12

D. FcRn

Question 13

Which of the following biochemical moieties is IgG most likely to bind?

A.Carbohydrate

B.DNA

C.Lipid

D.Protein

Answer 13

D. Protein

Question 14

Which of the Rh genes is more immunogenic? Are most people RhD-Postive (Rh-pos) or RhD-Neg (Rh-Neg)

Answer 14

Rh D; Rh-D Pos

Question 15

When are you most concerned about a mother regarding Rh-type? What do you assume about the baby?

Answer 15

Rh-Neg; you assume the baby is positive

Question 16

What is Rh disease of the newborn called?

Answer 16

Hemolytic disease of the fetus and the newborn (HDFN)

Erythroblastosis fetalis

Question 17

What is Rhogam? Who is given to? What is its MOA?

Answer 17

Rhogam: IgG against RhoD

Rh negative mothers

MOA: Rhogam binds fetal RBCs, Inhibits B cells, Induces complement-mediated lysis of fetal RBCs in maternal circulation

Question 18

Classify the following dz’s based on their indirect and direct Coomb’s test results: Transfusion reaction, drug-induced hemolytic anemia, Rh dz of the newborn, autoimmune dz.

Answer 18

Positive direct and positive indirect

Transfusion reaction

Rh disease of the newborn

Autoimmune diseases

Positive direct and negative indirect

Drug-induced hemolytic anemia

Negative direct and positive indirect

Not possible