Host Defenses II

adaptive immune response

third line of defense

antigen

molecule that stimulates an immune response

immunological memory

rapid immune response during secondary exposure

cellular response 

t cell immunity 

humoral response

B cell immunity

eliminate an identified pathogen and remember it for next time

what is the goal of adaptive immune response

proteins or polysaccharides

most antigens are _________________

bacterial, parasitic, fungal, or viral

common antigens

immunogenicity

The ability of a substance that contains antigens to cause the body to make an immune response against that substance

epitopes

the specific part of an antigen that is recognized by the immune system, particularly by antibodies and immune cells like B and T cells

complete antigens

proteins, polysaccharides and lipids are all examples of

haptens (incomplete antigens)

small molecules is an example of

Stage 1. antigen presentation

the breakdown of a cell's own proteins or those from an intracellular pathogen into small peptides within the cytoplasm, which are then transported into the endoplasmic reticulum

Leukocytes (WBCs), Lymphocytes, T cells, B cells, low levels normally

What are the main players on adaptive immunity

yes; same shape

Do T cells recognize the same epitope?

clonal expansion

the process of rapid cell division that creates a large number of genetically identical cells from a single parent cell

cluster of differentiation (CD) proteins 

unique identification tags on cell surfaces, allowing scientists to distinguish between different cell types, such as helper T cells (CD4) and cytotoxic T cells (CD8)

stage 1: antigen presentation

primarily organized by T helper cells and carried out by T cytotoxic cells

T helper cells = the organizers/commanders
They respond to antigen presentation and tell other cells how to respond.

what do T helper cells do

T cytotoxic cells = the killers
They do the actual destruction of infected cells.

what do T cytotoxic cells do

T helper cells

release cytokines that can stimulate or suppress other white blood cells

T cytotoxic cells

destroy infected cells, cancer cells and transplanted tissues

B cell

stimulated by T helper cells; activated ______ will secrete antibodies

cellular response promoted

when T helper 1 cells stimulate T cytotoxic cells what kind of response is that 

humoral response promoted

when T helper 2 cells stimulate b cells what response is that

major histocompatibility complex (MHC)

to bind peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T cells; presents antigens to immune system 

MHC 1

molecule found on the surface of all nucleated cells in the body except RBCs; acts like a “display window” that shows what’s happening inside the cell; activates CD8 T cells (cytotoxic)

MHC 2

molecule found only on special immune cells called antigen-presenting cells (APCs) macrophages, B cells and dendritic cells; display antigens the cell has taken in from the outside world; activates CD4 T cells (helper)

T cell activation 

the process where a T cell becomes “switched on” after recognizing an antigen, allowing it to start an immune response; primary and secondary activation signals

proliferation

T cell activation turns one T cell into thousands of identical T cells

differentiation

when an activated T cell develops into a specialized type of T cell with a specific job

Various T h subclasses

activate B cells, T cytotoxic cells, macrophages and other white blood cells

Memory T h and memory T c

long lived cells that remain in lymphatic tissues; quickly mount immune response upon reexposure 

Various T c subclasses

seek and destroy cells infected with intracellular pathogens and cancer cells; activate macrophages 

T helper cell differentiation 

dependant on cytokine release from APCs; certain cytokines stimulate cellular response other stimulate humoral response

interferons

recruit T cytotoxic cells and increase MHC I production

Humoral response stage 1

B cells are antigen presenting cells; does present antigens on MHC II

Humoral stage 2

T dependent B cell activation; T helper cells; primary route of B cell activation

Humoral stage 3

B cell proliferate and differentiate 

proliferation of B cells

only B cells that can bind the antigen proliferate 

b cell differentiation; plasma cells

release antibodies

plasma cells

secrete antibodies that bond to specific antigen that triggers immune response

memory cells

reside in lymphatic tissues

antibody monomeric structure

2 heavy chains, 2 light chains and antigen binding sites

no

can B cells alter what epitope it recognizes

neutralize antigens, activate complement and increase phagocytosis

what can antibodies do 

neutralize antigens

antibodies block toxins or antigens from binding to host cells

increase phagocytosis

enhanced as antibodies precipitate, agglutinate or opsonize antigens

gene shuffling

generates diverse repertoire of antigen receptors

The body avoids attacking itself through self-tolerance mechanisms, where self-reactive immune cells are eliminated or turned off during development, and activation requires extra safety signals that healthy self-cells do not provide.

how does the body not accidentally recognize itself?

immunological memory

allows for rapid response upon secondary exposure

antibody titer

amount of Ab present in blood

affinity

the strength of the attraction between two molecules, such as an antibody and its antigen, a receptor and its ligand, or an enzyme and its substrate

MHC I presents intracellular antigens while MHC II presents extracellular antigens

Describe the different antigens typically presented by MHC I and MHC II.

plasma cells produce antibodies while memory cells are used to “remember” past infections to provide protection against future infections.

What is the difference between B memory cells and plasma cells?

Artificially acquired passive immunity

What type of immunity is gained by using an antitoxin on someone who was bitten by a snake?

T helper cells

CD4 is associated with what type of T cell?

thymus

Where in the body do T cells finish maturing?