Exam 2 pt 1 /quiz 2

lymphocytes

• the cellular part of the adaptive immune system

• small mononuclear cells with very scant basophilic cytoplasm

B cells, T cells, NK cells

alpha beta and gama sigma

what are the two chains of the TCR?

TCR: MHC, costimulatory receptors and cytokines

what are the 3 signals for activation?

TCR complex

1. TCR: Recognize

2. CD3- signal

3. CD4/CD8: stabilize

CD3

mediates signaling and cell activation

all cells have CD3

CD4

helper T cells

• MHC II, from extracellular sources

CD8

Cytotoxic t cells

• MHC I, from intracellular sources

B cells

eventually become antibody secreting plasma cells

t cell receptor

• 2 chains (alpha beta and gama)

variable end

binds specific antigen

constant end

• non specific

intracellular pathogens

•have to leave the cell sometime

–They can be phagocytized and presented on MHC II to activate CD4 T cells

extracellular pathogens

•may be phagocytized and present by APCs through the MHC I

–Professional APCs are capable of doing this, and this is termed “cross presentation”

linear epitope

antigens

peptides that are presented by MHC

superantigen

–Ignore TCR variable region fitting

–Bridge MHC and a CLASS of TCR

–Activate 2-20% of TCR at once

–Acute Toxic Inflammation

–Bacterial eg and Viral eg

CD28

when CD40 on APC interacts with CD40L on T cells T cells express____

Signal 2

when CD80 and CD86 on APC interact with CD28 on T cells

CTLA-4

produced when eventually T cells produce less CD28

• binds CD80/86 but this time induces downregulation of T cell

• PD-1

costimulatory cytokines

•Activated APC + Ag = Activation

–Requires co-stimulation and cytokines

–The type of cytokines being produced by the APC will largely determine the entire future response of the T cell

•In general, if the APC produces:

–IL-12, IL-18, IFN-g à Th1

–IL-4, TSLP, IL-33 à Th2

–IL-6, TGF-β, IL-23 à Th17

–IL-2, TGF-β à Treg

only when activated

when does APC express inflammatory cytokines and costimulatory molecules?

no, it becomes anergic

does the T cell activate if not all 3 signals are present?