University:
York University
Course:
SC/BIOL 3120 | Immunobiology
Academic year:

2023
Views:

164

Pages:

3
Author:

Niklas

B-cell Differentiation: ACTIVATED CELLS! following stimulation at the B cell/Tcell boarder, B-cells con differentiate ints one of the following Antigen 1) plasmablasts differentiated B-celts that have begun to secrete antibodies, have not yet lost the capacity to proliferate and still bear cell surface BCR plasma til differentiated B-cells that con na lenger divide, bear little to ne cell surface immunoglobin, and rapidly secrete large #s of antibody molecules 2) Germinal Center cells Some activated B-cells move iths the follicles and initiate a germinal center response germinal center formation requires CD40/2040L interactions between B/T cells cytokines from FDCs and Ten stimulate proliferation callegion of sells p FDC (fellicutar dendritie cell): does not present Ag nas dendrite the things an il 3) memory cells saved for later purpose. collects antigen with its receptors "Tigand curated 2 things happen in the germinal center: stimulation signals for B-cell activation via Treell binding! -affinity malization 1) MHC class 2 presents to TCR - class switching 2) interaction between CD40/coчос analogowser / Mnding 102 dark zant densely packed w/ proliferating B-artis 5) cytokines bind to B-cell ligget zara 8-com interspersed / a netwers of FDCs CD4 secreates cytokines for B८५॥ Affinity Maturation/Sematic Hyper mutation occurs within germinal center produces individual point mutations in ly heang and light chain rearrangements mutaliens increase over time and with repeated exposures fstowed by affinity selection resulting in increased affinity for the antigen over time. Rekivation - Induced Dasminase (ALD) randomly deaminates cytodine into urine mechanism to fix it prochers oportunity for matation by allesing decsycytidine bases - RANDOM! Changes DNA sequence which changes proteins mutational apparatus torgeting molational hot spots are sequence matils for more likely to be targeted, preventing mutations in suniy ereus Antigen induced selection of B-cells with higher affinity B-cells that can bind process and present mure antigen to T-cells for cytokine nasistance survival higher affinity 8-ctms may actually steal Ag from lower-aflinity B-cents promoting their man survival signals process #2 class switching high affinity signals for class switch recombination: -B-cell must receive co-stimulatory slanals from CD40 to engage in CSR the cytokine signal teceived determines the produord isotype accuts within the germinal center after contact with antigen switching constant region AID is responsible for class switching Lie Summary: T-dependent B-cell Receptor process #3 memory responses mest acwly generated cells are last at the end of the primary immunе изрове -after antigen is demed, mast effector cells are na tonger required memory provides tapid/strong response to secondary infection How do we burn off cell feedback inhibition negative signaling throug Fc yllb receptor inhibits B-cell activation excess antibody hinds to receper ITIMS immunoreceptor tyresine based inhibitery metils