Class Notes (808,126)
Canada (493,084)
UOIT (1,636)
Biology (294)
BIOL 2050U (48)


4 Pages
Unlock Document

BIOL 2050U
Peter Cheung

LYMPHOCYTE ACTIVATION all immune system responses begin with NAÏVE T CELL ACTIVATION features of T-cell activation that are distinct from other receptor-ligand processes requires MHC-presentation small proportion of T cells can respond to ANY antigen many different MHC-peptide combinations are presented by a single APC self-reactivity is a concern Naive T-cell activation causes their DIFFERENTIATION CD8+ cells respond to MHC class I  indicates viral infection activation causes diffentiation into CYTOTOXIC T CELLS CD4+ cells respond to MHC class II  indicates microbial infection activation causes differentiation into TH1 or TH2 cells TH1 – inflammatory response (macrophage mediated) TH2 – antigenic response (B-cell mediated) T CELL COSTIMULATION – signal 1 = antigen-MHC signal 2 = antigen independent costimulatory signal (B7) **ensures that only APC’s can cause T-cell differentiation** APC’s: DC’s – MOST important activator of T-cells; presentS viral antigens Macrophages – present bacterial antigens B cells – present bacterial and viral antigens STAGES OF T-CELL ACTIVATION INITIAL ENCOUNTER WITH APC’s – SIGNAL 1 occurs in lymph nodes, Peyer’s Patches, spleen 1) T-cells diapedese through the endothelial walls (ICAM mediated) 2) upon APC encounter, binding is first antigen INDEPENDENT CD2 (T cell) and LFA-3 (APC) 3) antigen-dependent binding involves CD4/CD8 AND TCR to MHC on APC mediated by ITAM, found within the INVARIANT chain of TCR (cytoplasmic CD3 complex) ITAM is phosphorylated (by LCK on CD4 or CD8)? SH2 binding domain is exposed that binds ZAP-70 (protein kinase) (LCK phos. ZAP-70)? ZAP-70 phos. LAT  TYROSINE kinase cascades activated 4) cascade 1: phospholipase C (PLC) leaves PIP2 to IP3 and DAG IP3 causes intracellular increase in Ca++ Ca++ activates CALCINEURIN (phosphatase) CN dephos. NFAT, exposing an NLS NFAT can enter nucleus and stim. IL2 txn **CN is a target of immunosuppressive drugs** DAG activates Protein Kinase C cascade 2: Ras activated **both casca
More Less

Related notes for BIOL 2050U

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.