Type II Hypersensitivity

Question 1

Also known as antibody-mediated cytotoxic hypersensitivity.

Answer 1

Type II Hypersensitivity

Question 2

The immunoglobulins involved in the mechanism of type II hypersensitivity

Answer 2

IgG and IgM

Question 3

The IgM and IgG are directed against?

Answer 3

Antigens found on the cell surface

Question 4

The three major effects that can happen wen the antibody binds to a cell

Answer 4

(1) The cell can be destroyed
(2) the function of the cell can be inhibited
(3) the function of the cell can be increased above normal.

Question 5

Cell damage can occur by several different mechanisms which involve complement as well as antibodies:

Answer 5

(1) Activation of the classical pathway of complement can lead to the formation of the membrane attack complex and cell lysis.
(2) Coating of the cell surface by antibodies can promote opsonization and subsequent phagocytosis of the cells.
3) Cell damage can result from the mechanism of antibody-dependent cellular cytotoxicity (ADCC)

Question 6

Opsonization can occur through?

Answer 6

Binding of IgG antibody to Fc receptors on macrophages and neutrophils OR binding of cell surface C3b to complement receptors on phagocytic cell

Question 7

It is mediated through binding of IgG antibody to its corresponding antigen on the target cell and to Fc receptors on macrophages or natural killer cells.

Answer 7

Antibody-dependent cellular cytotoxicity (ADCC)

Question 8

Clinical examples that involve destruction of cells by type II hypersensitivity includes

Answer 8

• Blood transfusion reactions
• Hemolytic disease of the newborn
• Autoimmune hemolytic anemia.

Question 9

What will happen when antibody blocks the binding of a physiological ligand to its receptor?

Answer 9

Dysfunction of the cell

Question 10

An example of autoimmune disease that results to dysfunction of the cell (esp. affects the neuromuscular junctions > muscle weakness)

Answer 10

Myasthenia gravis

Question 11

Overproduction of cells can result on what autoimmune disorder of the thyroid gland?

Answer 11

Graves’ disease

Question 12

What hormone is affected in Graves disease?

Answer 12

TSH

Question 13

An example of cell destruction that results from antibodies combining with heteroantigens.

Answer 13

Transfusion reactions

Question 14

Major groups involved in transfusion reactions

Answer 14

ABO, Rh, Kell, Duffy, and Kidd systems

Question 15

Anti-A and anti-B antibodies are naturally occurring antibodies that are also called as

Answer 15

Isohemagglutinins

Question 16

These are probably triggered by contact with identical antigenic determinants on microorganisms

Answer 16

Isohemagglutinins

Question 17

The extent of the reactions depends on the following factors (6)

Answer 17

*The temperature at which the antibody is most active
* The plasma concentration of the antibody
* The immunoglobulin class involved
* The extent of complement activation
* The density of the antigen on the RBC
* The number of RBCs transfused40

Question 18

If a reaction occurs only below 30°C, what is the next step?

Answer 18

Disregard (*because antigen–antibody complexes formed at colder temperatures tend to dissociate at 37°C)

Question 19

May occur within minutes or hours after receipt of incompatible blood

Answer 19

Acute hemolytic transfusion reactions

Question 20

Most often associated blood group and antibody in acute hemolytic transfusion rxn

Answer 20

ABO blood group, IgM class

Question 21

Occurs because of complement activation, resulting in the release of hemoglobin and vasoactive and procoagulant substances into the plasma.

Answer 21

Intravascular hemolysis

Question 22

Intravascular hemolysis may induce?

Answer 22

Disseminated intravascular coagulation (DIC)
Vascular collapse
Renal failure.

Question 23

Reactions occur within the first 2 weeks following a transfusion and are caused by an anamnestic response to the antigen to which the patient has previously been exposed

Answer 23

Delayed hemolytic reactions

Question 24

Antibody responsible for Delayed hemolytic reaction

Answer 24

IgG

Question 25

Antigens/Blood group involved in delayed hemolytic reaction

Answer 25

Rh, Kell, Duffy, and Kidd blood groups

Question 26

In, delayed reaction, antibody-coated RBCs are removed extravascularly in what organs?

Answer 26

Spleen and liver

Question 27

T/F: In delayed hemolytic reaction, intravascular hemolysis does not take place to any great extent because IgG is not as efficient as IgM in activating complement

Answer 27

True

Question 28

Appears in infants whose mothers have been exposed to blood-group antigens on the baby’s cells that differ from their own

Answer 28

Hemolytic Disease of the Newborn (HDN)

Question 29

Severe HDN is called

Answer 29

Erythroblastosis fetalis

Question 30

The mother produces what antibody that can cross the placenta to destroy the fetal rbcs

Answer 30

IgG antibody

Question 31

Most common antigen involved in severe reactions

Answer 31

D antigen, (RH blood group)

Question 32

Other antibodies associated with HDN include

Answer 32

anti-c, anti-C, anti-E, anti-e, and less commonly those associated with the Kell, Duffy, and Kidd blood groups

Question 33

Bilirubin levels above 20 mg/dL are associated with deposition in tissues such as the brain and result in a condition known as

Answer 33

Kernicterus

Question 34

If serum antibody titrations during the pregnancy indicate a high level of circulating antibody, this can be performed

Answer 34

Intrauterine transfusion

Question 35

Anti-D immune globulin, called Rhogam, is administered prophylactically at

Answer 35

28 weeks of gestation and within 72 hours following delivery

Question 36

An example of a type II hypersensitivity reaction directed against self-antigens because individuals with this disease form antibodies to their own RBCs.

Answer 36

Autoimmune Hemolytic Anemia

Question 37

When the underlying cause of antibody production is unknown; this is referred to as

Answer 37

Idiopathic autoimmune hemolytic anemia

Question 38

Associated diseases in autoimmune hemolytic anemia may include

Answer 38

- Viral or respiratory infections (infectious mononucleosis, cytomegalovirus, or chronic active hepatitis) - Immunoproliferative diseases (chronic lymphocytic leukemia and lymphomas)

Question 39

Drugs that can act as haptens after binding to proteins on the RBC membrane. They can stimulate the production of anti-drug antibodies that destroy the RBCs, primarily through extravascular hemolysis

Answer 39

Penicillins and cephalosporins

Question 40

Drug that can modify the RBC membrane by facilitating binding of immunoglobulins and complement

Answer 40

Cephalosporin

Question 41

Drug that can stimulate the production of anti-drug antibodies that bind to the drug to form soluble immune complexes

Answer 41

Quinidine and phenacetin

Question 42

Drug that can induce hemolytic anemia by stimulating production of autoantibodies against the RBC membrane

Answer 42

Methyldopa

Question 43

Severity of the hemolysis is affected by what subclass of IgG involved

Answer 43

IgG3 and IgG1

Question 44

This antibody attaches to B cells and causes a decrease in antibody production. It can use as a treatmnet with warm autoimmune hemolytic anemia

Answer 44

Anti-CD 20 (rituximab)

Question 45

Can be produced secondary to certain infections, most notably Mycoplasma pneumonia and infectious mononucleosis but also respiratory viruses and HIV

Answer 45

Polyclonal cold agglutinins

Question 46

Occurs most often after infection with certain viral illnesses, including measles, mumps, chickenpox, and infectious mononucleosis. Px produces a biphasic autoantibody

Answer 46

paroxysmal cold hemoglobinuria

Question 47

Examples of type II hypersensitivity reactions to tissue antigens include some of the organ-specific autoimmune diseases

Answer 47

Goodpasture syndrome, Hashimoto's disease, Myasthenia gravis and Insulin-Dependent Diabetes Mellitus

Question 48

Performed to detect transfusion reactions, HDN, and autoimmune hemolytic anemia. (Coombs discovery in 1945)

Answer 48

Direct Antiglobulin Test (DAT)

Question 49

Used in the crossmatching of blood to prevent a transfusion reaction. It can either determine the presence of a particular antibody in a patient or type patient RBCs for specific blood group antigens

Answer 49

Indirect Coomb's test