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

2023
Views:

43

Pages:

3
Author:

Niklas

(immature B) what if they recognize self-antigen? tolerance: do not recognize self antigen (no response) * central tolerance: occurs in primary lymphoid tissue * peripheral tolerance: occurs in the periphery - parapenia response (spelling!) → we depend on this mechanism to make sure we get rid of the autoreactive B-cell Negative Selection: 1) Apoptosis 2) Anergy: functional state of unresponsiveness - not dead "sleeping" 3) Receptor Editing: slight changes to receptor - 12/13 rule - can only happen in the LIGHT chain B-Cell Development After the Bone Marrow: once the B-cell has a functional receptor, they are called "B-2" B-cells B-1 B-cells (always secreting antibody) Marginal Zone B-cells (MB) The Role and Function of Mature B-cells: mature primary B-2 B-cells migrate to lymphoid follicles * express high levels of IgM/IgD on their surfaces * recirculate between blood and lymphoid organs * help to respond to antigens (with T-cell help) by producing antibodies * half-life ~4.5 months in periphery VDJ Recombination in T-Cells: Two classes of T-cell receptor: αβ T-cell receptor γδ T-cell receptor γδ T-cells are important during gestation but decrease and αβ T-cells increase right before birth. γδ T-cells are important in barrier immunity and appear to recognize "unconventional" antigens presented by "unconventional" MHC molecules. γδ T-cells can secrete cytokines immediately after exit from the thymus. T-Cell Development: Leaves bone marrow and migrates to thymus (now thymocyte). Thymocyte: an immature T-cell. Double negative: neither CD4 or CD8. Double positive: both CD4 and CD8. Lineage commitment. Mature T-cells: express antigen-specific TCR. Tolerant to self. Restricted to self MHC. Negative selection to make sure it's not autoreactive. MHC Restriction T-crils only wind farinan antigen when the antigen is bound to self MHC Thymic Cortex (pooilive πελεκλίση) self restriction griduces hypothesis and not to light bulbs lesse both negative and positive selection location thymies cortex mediated by cortical thymic epithelial colls (CTEC's) Thymic Medula (negative selection) Self sterance TCR de not bind to self-fisse negative selection only AIRE (Autoimmune Regulator) transcription factor in the thymus that can turn on every gene -why the developing T-cell will see every type of gene пробилка T-cell to patrids it would see in dysfunctional AIRE leads is wide spend autoimmunity the way to see it intive DP strongly reactive T-cells are deiched Linenge Commitment the determination of co vs CDe Instructive Medle during selection, the TCR has an affinity for MHL (CD) MHL (104) Stechealls Madle the cell randently down-teguintes either bear (D Winetic Signaling Medle cets commit to the cou lineage if they recieve a contindres signal in respame to TCR cuteceptor engagements but commit is the CD lineage it that signal is interrupted current margh