adaptive immunity

What can microbes overcome

They can overcome the innate immune response and cause infection

What happens when the microbe bypasses the innate IR

Adaptive immunity responds against these microbes

What is unique about adaptive response

Specifics

Memory - faster and bigger response when microbe encountered second time

what are the 2 types of adaptive immune response

• antibody-mediated

• Cell-mediated

how do adaptive and innate immune response interact

they are not mutually exclusive

they do have to interact with each other

what is an antigen

any molecule that reacts specifically with an antibody or antigen receptor on lymphocyte

what is an immunogen

antigen that can reduce an immnune response

needed for seceondary response

immunogenic

relative ability of antigen to elicit immune response

what are antigenic determinants known as

epitopes

what are epitopes

discreet regions of antigen molecule specifically recognized by adaptive immune response

antibody

• produced by B-lymphocytes = B cells

• neutralise free-floating particles

• in response to extracellular antigen, B cell proliferate and differentiate into plasma cells

what is the structure of an antibody

• Y-shaped proteins

• 2 identical arms and 1 stem

what do the arms of an antibody do

bind to specific antigens

what is the function of the stem of an antibody

tags antigen for destruction by immune components

what are the two type of light chains

λ and κ

both L chains are identical

how many specialties can a given B cell produce

only one specificity

what are the five types of heavy chains in antibodies

μ = IgM

γ = IgG

α = IgA

δ = IgD

ε = IgE

IgG

• make up most of serum immunoglobins

• monomeric structure

• four classes - IgG1, IgG2 , IgG3, IgG4

what is the most prevalent subclass of IgG

IgG1

functions of IgG antibodies

opsonisation

neutralization

main type of antibody in secondary response

crosses placenta - provide passive immunity to fetus

IgM

• monomeric, attached to B cell surface as a receptor

• pentameric in serum, 5 monomers held together by a J chain

functions of IgM

first Ab class produced during primary response

Ag receptor on B cells

activates innate defences

agglutinates particulate Ag

igD

• monomeric form

• found in serum and on B cell surface as receptor

• very low amounts

• unknown function

IgA

• primary Ab made by cells of mucous membrane

• secretory Ab made in mucosal secretion

• low amount and monomeric in serum

• dimeric secretions - resistant to proteases, more stable

function of IgA

• neutralise bacteria and viruses by preventing them from attaching to mucous membranes

• passive immunity - breast milk

IgE

• monomeric

• low levels in serum

• Ag receptors on mast cells and basophils

function of IgE

anaphylactic hypersensitivity

functions of humoral immunity

• activate classical complement pathway

• activate phagocytic cells

• neutralisation of pathogens

what kind of cells are involved in cell-mediated immuniity

T cells

how do T cells recognise antigens

antigen must be presented by one of body’s own cells

TCR bind to complex of MHC molecule and peptide - activate T-lymphocytes - help macrophages kill intracellular parasites - Th1 + Class II MHC - T cell release macrophage activating factors (IFNγ)

what do TCR bind to

complex of MHC and helper T cells

what do TH1 cells release do activate macrophages

Macrophage activating factors (IFNγ)

what are the two major functional populations of T cells

cytotoxic T cells - differentiate into Tc which destroy infected or cancerous cells - CD8

helper T cells - differentiate into Th which activate B cells and macrophages - CD4

what do cytotoxic T cells recognise

recognise Ag presented by MHC class I

what is CD

cluster of differntiation

what do helper T cells activiate

B cells and other immune cells

Th1

activate macrophages

Th2

activate B cells

what do helper T Cell recognise

Ag presented by MHC class II molecules

what type of immunity do T lymphocytes provide

cell mediated immunity

what happens when T-lymphocytes are activated

• help macrophages to kill intracellular parasite

• T -lymphocytes inhibit intercellular replication of viruses

what do Th1 cells release when activated

Macrophage activating factors (IFNγ)

what is the function of CD8 T cells

destroy infected and cancerous cells

what do CD4 T cells activvate

B cells and macrophages

what type of MHC molecule do helper T cells recognise

MHC class II molecules

how do you differentiate between B-cells and T-Cells

difference in surface markers

B cells - surface immunoglobin

T cells - T cell Receptor

what happens when lymphocytes mature in the primary lymphoid tissues

a population of cells are generated that are able to recognise and respond to 1 epitope

what is clonal selection in B- lymphocytes

only B cells capable of making correct Antibody binds to antigen.

clonal expansion

Cells that bind Ag begin dividing, produce population of cloneswh

what is the significance of somatic mutation in B-cells

they allow for further selection of B-cells

what happens when antigen encounters B-cells

it will send signal for that specific one to divide

what is the process of clonal selection and expansion in T-lymphocytes

similar to B cells only difference is that there is no further selection dure to somatic mutation

What is the role of memory cells in the immune response?

They provide a quicker response to future antigens

What are cytokines?

Soluble intercellular communication factors

What role do cytokines play in the immune system?

Control infection and development of pathology

What is the function of interferon?

Provides immunity against viruses

How do T-helper subsets interact?

They exhibit mutual antagonism

What regulates the immune system?

Antigen concentration and antibody feedback

What is the relationship between the adaptive and innate immune systems?


Adaptive immune system augments the innate IR

What are B-lymphocytes effective against?

Bacterial toxins and extracellular bacteria

What is required for B-cell activation by antigens?

Help from T-cells

What is the role of regulatory T cells?

They help regulate the immune response

What is apoptosis in the immune system?

Programmed cell death of immune cells