adaptive immunity 2

what is a thymus independent antigen?

a large antigen made up of many epitopes, where lots of b cells receptors can cross link on surface of the b cells, which triggers the b cells to divide and form antibody

how does a b cells recognize an antigen?

b cells have a specific antibody on their surface

where do t cell differentiate ?

in the thymes

what is the overall function of the t cells in the adaptive immune response?

help the b cells to turn on antibody production if the antigen is not large enough( thymus dependent antigen)

describe the steps in b cells and th2 cell binding?

b cells presents antigen on the surface on its cell through the mhc-2 complex. the t cells binds and the binding is stabilized through cd4. the binding causes the release of INT2,4,5 which activate the B cell.

how do macrophages stimulate the TH2 cells to divide?

macrophages express antigen on their surface through mhc2 complex, which activates th2 cells which release IL 1 which stimulates the TH2 cells to divide and aid and bind to b cells.

how are macrophages stimulated to increase phagocytosis

th1 cells recogenise antigen and bind to macrophagses. they release IFN gamma and also TNF and other cytokines to increase the response

what cells stimulates the macrophages to situmlates phagocytosis?

th1 cells

how are t killer cells activated?

TH1 cells cooperate with tcell precursor to differentiate into killer cells which recognize non self antigen on MHC 1 complex of virally infected cells, and mature to killer cells

how do t killer cells destroy virally infected cells?

release of perforin through degranulation which leads to forms pores in the membrane.

what is a hypersensitivity reaction?

an exaggerated immune response

what happens during first exposure type 1 hypersensitivity ?

IgE antibodies are made against allergens which binds to MAST cells through the fc receptors making them sensitive

what happens during second exposure type 1 hypersensitivity?

when the antibodies bound to MAST cells come into contact with allergens they cause degranulation leading to the release of histamine, leukotrienes and heparins.

what are some symptoms of a type 1 hypersensitivity?

bronchoconstriction, vasodilation, eodema, swelling

what happens during a type 2 hypersensivity reaction?

this is when igE or igM antibodiesare made against self surface tissues which stimulate the complement pathway resulting in cell death through lysis or mediators

what is an example of type 1 hypersensivity?

asthma, conjuctivitis

what is an example of a type 2 hypersensivity?

blood transfusion from different blood group

what happens during a type 3 hypersensitivity?

antigen antibody complexes deposit in blood vessels which triggers hypersensitivity through complement pathway

what are the three main diseases that can lead type 3 hypersensitivity by depositing complexes around the body?

persistent infection with weak immune response, autoimmune disease, repeated inhalation of allergens such as mold

what is an examples of type three hypersensitivity?

SLE

what happens during type 4 hypersensitivity?

antigens are phagocytosed by macrophages and become APC which present to delayed type hypersensitivity t cells. this cause proliferation and attraction cytokines, interleukin, basophils causing hypersensitivity.

what are some examples of type 4 hypersensitivity reactions?

TB skin test, allergic contact dermitis