Looks like antibody

On surface of T Cells

Has variable and constant region

Two chains (alpha and beta rather than light and heavy)

Undergo somatic recombination to increase diversity

Have only ONE antigen binding site

Helper T cells

Release cytokines to activate B cells

Have CD4 surface molecules

bind to MHC2 APC cells

secrete cytokines

Surface molecule on helper T cells

assists the T cell receptor (TCR) to activate its T cell following an interaction with an antigen presenting cell

Gets engulfed and antigen presented (not originally inside the cell)

Gets presented to Helper T cell by APC

Cytotoxic T cells

Have CD8 molecule

Bind to MCH1 cells

Secrete perforin which kills pathogens

On surface of cytotoxic T cells

Binds specifically to MHC1 

All nucleated cells present this in the groove of MHC1 molecules

Originated inside the cell

Secreted by cytotoxic T cells

Kills the infected B-Cell by inducing apoptosis

Created by the phagocytic event

Phagocyte's Toll-like receptor binds to PMP

Turns on gene in phagocyte to make B7 protein which interacts with T cell protein CD28

protein which interacts with T cell protein CD28

Produced during the second signal

A cytokine released from nearby activated helper T cells for cytotoxic T cell activation

Helps differentiate between self and non-self by potentially binding to IL-2 receptors on self

considered mature, but is distinguished from activated T cells or memory T cells, as it is thought not to have yet encountered cognate antigen in the periphery

Recognize antigen presented by dendritic cell that expresses co-stimulatory molecules

May become activated, allowing them to proliferate and develop their effector functions

Activated T Cell (macrophage)

Helper T Cell?

Dependent: Need helper T cells to stimulate the proliferation and differentiation of B cells that have engulfed T-dependent antigens

Independent: If a repeat antigen (capsule) binds more than one B cell receptor, the B cell can proliferate without a helper T cell (weaker response)

Has two parts: T-independent antigen CONJUGATED to a protein

B cell binds to T-ind antigen, B cell internalizes whole conjugate, digests and presents protein on MHC2, T_H recognizes protein, antibody produced to original T-ind antigen, memory B cells and plasma cells also produced

much stronger response

Bind to B cell and produces the antibodies necessary

No memory cells are produced

T cells respond to proteins better than polysaccharides

Suppressor T cells

Reduce the T cell response once antigen is gone (when infection is over)

Prevent from runaway immune response

One of the kinds of T cells that clonal T cells turn into

Long lived

Can be reactivated by just binding antigen (no need for CD28/B7 signal)

One of the kinds of T cells that clonal T cells turn into

type of infection-fighting T cell (also known as a T lymphocyte) that can recognize foreign invaders such as bacteria or viruses, that were encountered during a prior infection or vaccination. At a second encounter with the invader, memory T cells can reproduce to mount a faster and stronger immune response than the first time the immune system responded to the invader.

A process that selects the good T cells that only recognize self antigens

Occurs in the thymus during T cell development and only 5% are selected

T cells must bind MHC1 in the thymus to be stimulated to develop

T cells that fail to recognize MHC could never function and are left to die

T cells must NOT bind to an antigen on the MHC (a self antigen, since the thymus is sterile)

If they do, the binding is too tight for them to be released to the circulation (T cell sticks to thymus and dies)

Kills whatever cell it attaches to (need specific receptor)

Binds to F_c part whose F_ab parts are bound to bacterium

Binds to "kill receptor" or any other cell

Release cytotoxins to kill attached cell (self or non-self)

Antibody-Dependent Cell-Mediated Cytotoxicity

mechanism of cell-mediated immunity whereby an effector cell of the immune system actively lyses a target cell that has been bound by specific antibodies

Used by NK cells

Signal on cells that activates NK cells to kill them

MHC1 is considered a "cancel kill" signal

since cancer and viral-infected cells often lack MHC1, they fail to cancel the kill signal