Hypersensitivity Type II

Question 1

3 examples of Type II hypersensitivity reactions

Answer 1

1.Transfusion reactions
2. Hemolytic disease of the newborn
3. Drug-induced hemolytic anemia

Question 2

Type II hyper is mediated by?

Answer 2

Antibodies (IgG and IgM)against cell surface or extracellular matrix antigens

Question 3

CM of immediate vs Delayed Transfusion reactions

Answer 3

Immediate :
fever, chills, nausea, clotting within blood vessels, pain in the lower back and hemoglobin in the urine, (bilirubunemia)

Delayed:
symptoms are similar but milder and free hemoglobin is not detected in the blood or urine

Question 4

—————— is used to determine the ABO blood group of blood donors and transfusion recipients

Answer 4

Hemagglutination (clumping)

Question 5

Transfusion Reactions that begin immediately are most commonly associated with ABO blood-group incompatibilities, leading to ——————-?

Answer 5

Complement-mediated lysis (due to IgM)

Question 6

Delayed Transfusion Reactions are most commonly associated w/ Antibodies to other blood-group antigens such as Rhesus factor, leading to ———-?

Answer 6

incomplete RBC lysis 2-6 days after transfusion (IgG class mediated, which are less effective in activating complement)

Question 7

In blood transfusions, MHC matching is not necessary but blood must be matched for ——–and ————- antigens to avoid the rapid destruction of mismatched RBCs by antibodies in the recipient

Answer 7

ABO and Rhesus blood group antigens

Question 8

Blood types are referred to as A, B or O and the antigens that are associated with the blood types are identified as A, B, and H respectively
* Μost adults possess ——— antibodies directed toward ABH antigens they do not express

Answer 8

IgM

Question 9

What causes a transfusion reaction?

Answer 9

receiving blood that is not compatable w/ your blood –> the body will produce Abs (e.g. Anti-B IgM antibodies), which will attach to the blood cell type and cause desruction by complement mediated intravscular hemolysis

Question 10

what induces hemagglutination (Clumping)?

Answer 10

induced when anti-A or anti-B IgM binds to A or B blood group antigens on erythrocytes (Causing a transfusion reaction)

Question 11

Which antibody can Agglutinate IgG/ IgM?

Answer 11

IgM

* IgG cannot agglutinate

Question 12

what causes Hemolytic disease of the newborn (HDNB)?

Answer 12

when maternal IgG antibodies specific for fetal blood-group antigens cross the placenta and destroy fetal red blood cells

* only IgG abs can cross the placenta

Question 13

Individuals bearing the D allele of the Rh antigen are designated as [Rh+/- ]?

Answer 13

Rh-

• and those who do not as Rh+

note: ther are five alleles of the Rh antigen, expression of the D allele elicits the strongest immune response

Question 14

Consequence of sentisized Rh- mother fetrilized by a Rh+ father

Answer 14

Erythroblastosis fetalis - Hemolytic disease of the newborn
(HDNB)

(Second born not first)

Question 15

when does an Rh- mother become sensitized during pregnancy?

Answer 15

When an Rh + fetus’s RBC enter the maternal circulation during the first pregency during child birth (through the umbilical cord) –> this results in the production of anti-Rh plasma cells and memoery cells in the mother
* IgM is secreted to clear Rh+ fetal RBC in the mother’s blood, but memory cells remain

*note: first child is unaffected but second who is Rh+ will develop haemolytic aneamia if mother does not take RHoGAM

Question 16

how will an Rh+ fetus of a sentisized Rh- mother develop Heamolytic aneamia?

Answer 16

activation of IgG-secreting memory cells (from first pregnancy w/ Rh+ featus) results in the formation of IgG anti-Rh antibodies which can cross the placenta and damage the fetal red blood cells by complement activation

Question 17

how is Erythroblastosis fetalis (Heamolytic Anemia of the newborn) avoided in a Sensitized Rh- mother?

Answer 17

treated prophylactically with anti-Rh antibodies (RhoGAM) during gestation and again within 72 hours of delivery to eliminate the risk ofsensitization

Question 18

ingredients necessary for an Indirect Coombs test

Answer 18

1) Rh- RBC from the mother (Rh+ RBC from baby added to the sample) - causes IgG production
2) Then, add Coombs reagent (containing IgM)

a positive test–> Agglutination (if IgG is produced, IgM will bind to it causing Agglutination)
In a negative test –> no Agglutination as IgG does not Agglutinate

Question 19

What ingredients would be necessary to perform a direct Coombs test?

Answer 19

Rh+ RBC from the baby + Coombs reagent
if tests is postive–> Agglutination of the sample w/ Coombs reagent

Question 20

Contents of Coombs test?

Answer 20

contains human anti-immunoglobulin antibodies (anti-IgG antibodies) to detect the antibodies that cause hemolytic disease of the new born
(IgM which binds to IgG)

Question 21

What abx can induce all 4 types of Hypersensitivites (w/ various C)?

Answer 21

Penicillin

Question 22

what drugs can cause Hamolytic anemia?

Answer 22

1) Penicillin (Abx)
2) Ibuprofen, naproxen

* when drug is withdrawn, the heamolytic anemia disapears

Question 23

Test used for the detection of Hemolytic Disease of the newborn

Answer 23

Coombs test
(Coombs serum identifies anti-Rh antibodies)