Type 2 Hypersensitivity

Question 1

What is the difference between type 1 and type 2 hypersensitivity?

Answer 1

Type 1 is IgE mediated - and is against antigens NOT found/bound in the body. This causes mast cell degranulation.

Type 2 is IgM or IgG mediated - and is against antigens that bind to cells. This causes cellular damage by other immune reactions.

Question 2

Which immunoglobulins are present in type 2 hypersensitivity reactions?

Answer 2

IgG

IgM - create blood antibodies

Question 3

How long does a type 2 hypersensitivity reaction take to occur?

Answer 3

Can take seconds to hours

Question 4

What is the pathophysiology of type 2 hypersensitivity reactions?

Answer 4

Antibodies bind to self antigens creating a complex. This antibody-antigen complex is good if made on an infectious cell but not good if its made on a human cell.

Question 5

What are examples of type 2 hypersensitivity reactions?

Answer 5

Goodpastures syndrome
Graves disease
Reaction to penicillin - haemolytic anaemia, thrombocytopenia, neutropenia
Blood transfusion reactions

Question 6

What are examples of type 2 hypersensitivity reactions?

Answer 6

Goodpastures syndrome
Graves disease
Reaction to penicillin - haemolytic anaemia, thrombocytopenia, neutropenia
Blood transfusion reactions

Question 7

What is an important feature of type 2 hypersensitivity reactions?

Answer 7

It is tissue specific (not systemic like type 3 hypersensitivity reactions).

Question 8

When can haemolytic disease of the newborn occur?

Answer 8

When a mother is rhesus negative and baby is rhesus positive and mother comes into contact with babies blood during birth.
Mother creates IgG against rhesus and if she has another rhesus positive baby this will cross the placenta and cause haemolysis of the babies blood

Question 9

Where do the antibodies bind to?

Answer 9

The surface of the cell on the antigen.

Question 10

What complication does IgM antibodies have against blood in blood reactions?

Answer 10

It causes glutination of the blood

Question 11

What are the properties of Group A blood?

Answer 11

Have anti B antibodies
Can receive blood from Group A and Group O
Can give blood to group A and AB

Question 12

What are the properties of group B blood?

Answer 12

Have anti-A antibodies
Can give blood to B group and AB group
Can receive blood from group O, group B

Question 13

What are the properties of group AB blood?

Answer 13

Have no antibodies
Can receive blood from group A, B, AB and O (universal receivers)
Can only give blood to group AB

Question 14

What are the properties of group O?

Answer 14

Have anti A antibodies and anti B antibodies
Can receive blood group group O only
Can give blood to group O, A, B, AB (Universal donor)

Question 15

What inheritance determines your blood group?

Answer 15

Mendelian inheritance

Question 16

What happens when you mix the wrong blood groups?

Answer 16

Haemolysis

Question 17

What should be given to rhesus negative mothers with rhesus positive babies?

Answer 17

Anti D injection

Question 18

What happens in graves disease?

Answer 18

A thyroid stimulating antibody binds to the Thyroid stimulating cell receptors and stimulates thyroxine production
This causes graves disease, common in young woman

Question 19

what is central tolerance?

Answer 19

developing immune cells that are self reactivated are destroyed, this happens in the thymus (t cells) and bone marrow (b cells), some self reactive B and T cells escape

Question 20

What are the basic points of type 2 hypersensitivity reactions?

Answer 20

IgG and IgM mediated
Antibodies are directed against antigens bound to cells and make a complex
The complex produces an immune reaction
This is tissue specific and not systemic