Hypersensitivity

Question 1

Hypersensitivity

Answer 1

Altered state of immune responsiveness causing excessive inappropriate immune responses which lead to tissue damage

Question 2

What happens in Type 1 hypersensitivity?

Answer 2

Antigen come in
APC take up antigen and present to T helper cell
CD4 T helper cell activate B cells which activate plasma cells that release IgE
IgE bind to mast cells
Next time antigen arrive bind to 2 adjacent IgE antibodies
Degranulation of mast cell
Release of histamines and other mediators

Question 3

What antibodies are involved in type 2 hypersensitivity?

Answer 3

IgM and IgG

Question 4

Where are the antigens in type 2 hypersensitivity?

Answer 4

Cell surface

Question 5

What is the histology of type 1 hypersensitivity?

Answer 5

Basophils and eosinophils

Question 6

What is the histology of type 2 hypersensitivity?

Answer 6

Antibody and complement

Question 7

What is the histology of type 3 hypersensitivity?

Answer 7

Complement and neutrophils

Question 8

What is the histology of type 4 hypersensitivity?

Answer 8

Monocytes and lymphocytes

Question 9

Where are the antigens in type 3 hypersensitivity?

Answer 9

Soluble

Question 10

Where are the antigens in type 4 hypersensitivity?

Answer 10

Tissues and organs

Question 11

How does the response time change with different hypersensitivities

Answer 11

From 1-4 the time goes up as the type of hypersensitivity goes up

Question 12

What happens in type 2 hypersensitivity?

Answer 12

Can go through complement cascade or not:
IgM or IgG bind to antigen on cell
Activate complement cascade
Either opsonisation and phagocytosis
Either cell lysis by activating neutrophils
Either MAC forming pores through cell- cell lysis occurs
Or antibody binds to antigen on cell and NK cell recognises Ag-AB complex. Release porforin
Or antibody binds to antigen and mediates cellular dysfunction.

Question 13

What happens in type 3 hypersensitivity?

Answer 13

Antibody and antigen bind. Activates classical complement pathway, cause basophil degranulation etc.
Attracts neutrophils and causes them to degranualte

Question 14

What happens in type 4 hypersensitivity?

Answer 14

Antigen come in
Macrophage attaches to antigen
Present to T lymphocyte 
Cytotoxic T cell produced 
Inflammation and neutralisation of antigen

Question 15

Which hypersensitivity reaction is cytotoxic?

Answer 15

Type 2