Adaptive immune system

IgG

can cross placenta & aids in complement activation, toxin neutralization, opsonization for phagocytosis

Main one

IgA

Agglutination of antigens & found commonly in mucosal membranes/tears

IgE

binds surface receptors of mast cells & basophils

IgM

1st antibody made in primary immune responseD

Different ways antibodies help

1. agglutination - create larger target of viruses

2. prevent binding of pathogen

3. neutralize toxin

4. Opsonization - Fc portion of antigen binds to FcR of phagocyte (more efficient process)

5. activate complement proteins

Specificity of adaptive immune system

TCR & BCR/antibodies can only bind specific epitopes

Unresponsiveness to self of adaptive immune system

B & T cells undergo positive & negative selection to make sure they do are functioning properly (each one in its respective maturation areas)

positive selection - cell has activity & if no activity then apoptosis (testing if functional)

negative selection - cell must NOT have activity & if does then apoptosis (testing if reacts to self or not)

Where do mature naive b/t cells go?

blood stream circulating body and not concentrated in specific organs

b cells mature in

bone marrow

t cells mature in

thymus

clonal deletion

getting rid of self-reactive cells

Inducibility/clonality of adaptive immune system

TCR/BCR binds epitope it is specific for = activated

naive = not met their antigen yet

T cells must have their antigen presented by MHC on professional APC

True

mhc 1 presents

endogenous antigens & interact with CD8

found on ALL cells

mhc 2 presents

exogenous antigens & interact with CD4

only on professional APCs

professional antigen presenting cells

dendritic cells (not good at killing but uptake yes & main purpose = antigen presenting)

b cells

macrophages (good killers)

naive cd4 T-cells become

effector helper T cells (T_H)

naive cd8 T-cells become

effector cytotoxic cells (T_C)

IL-2 cytokine

proliferation & differentiation of T-cells

How is activation different between helper and cytokine t-cells?

helper t-cells can self activate bc IL-2 & IL-2R are both on cell but cytokine t-cells need IL-2 from helper t-cell to become activated

Cytotoxic t-cells (Tc) kill infected host cells same as NK cells which is by

releasing perforin (creates pores in membrane) and granzymes (induces apoptosis)

what is difference between NK & Tc?

in absence of MHC1 —> NK kill cell

In interaction of MHC 1 —> Tc kills cell

in order to induce expansion & differentiation B-cells must get help from

helper t cells

can b cells present any antigen like the other 2 professional APCs (dendritic and macrophages)?

NO only b cell receptor antigens

process of activation of b cell

first step

antigen binds to BCR (b cell receptor) and is endocytosed

b cell activation step 2

antigen is then presented on MHC 2 molecules s

step 3 - b cell activation

antigen on mhc II interacts with cd4 on helper t cell & t cell releases cytokines to activate expansion & differentiation of b cells

which cytokines are important for b cell expansion and differentiation

IL-4, IL-5, IL-13

a humoral immune response from the adaptive immune system is

antibody mediated — more for extracellular infections

a cell-mediated immune response from the adaptive immune system is

cytotoxic t-cell mediated — more for intracellular infections (viral infections)

which helper t-cell is associated with a humoral response of the immune system?

TH2

which helper t-cell is associated with a cell-mediated response of the immune system?

TH1

cytokine TFN-alpha and interferon-gamma (IFN-gamma) are

pro-inflammatory cytokines & stimulate macrophages

IFN-alpha/beta

produce a generalized antiviral state in infected cells and uninfected neighboring cells, which protects them from viral infection

IL-2

clonal expansion & differentiation of t-cells

IL-4, IL-5, IL-13

clonal expansion & differentiation of b-cells

attenuated vaccine is

live virus but not virulent (sabin)

cross-presentation

exogenous antigens taken up by phagocytosis/endocytosis & presented by MHC (1 instead of MHC 2) —> activate naive cd8 t-cells (cytotoxic t-cells)