Adaptive Immunity PDF

Adaptive Immunity Louis Pasteur Side Chain Theory Innate Adaptive Immune Response...

Adaptive Immunity Louis Pasteur Side Chain Theory Innate Adaptive Immune Response & cultured pathogens passaged them Paul Ehrlich founder of it vaccines provide 1st exposure (slow) I ~ it would weaken so he can inoculate he discovered antibodies antigens 2nd exposure is from the disease itself (fast) · - ppl and it would protect against disease theorized : specialized cells can make this led to invention of rabies vaccine antibodies that are selected to "fight" Aspects of Immunity Cellular Adaptive Immunity : T Cells Cellular Adaptive Immunity : B Cells adaptive immunity major cells thymus discovered 1960 max cooper discovered : lymphocytes T (thymus) lymphocytes surgical removal of Bursa from chicken T B lymphocytes Jacques Miller discovered : eliminates antibody production · surgical removal of thymus from mice they were still able to reject transplants eliminated adaptive immunity B cells : responsible for antibody production they could no longer make antibodies could no longer reject skin grafts bc T cells are responsible for self-nonself B Cells Bone Marrow Antigen Receptors B T Cell Receptors Structure B Cell Receptors Antibodies & I & mammalian B cell development occurs in B T cells have antigen - made of 4 chains : 2 heavy, 2 light bone marrow in medullary cavity receptors on the surface - are mbn-bound or secreted forms of the same mlc B cells complete their maturation there - have the same antigen specificity ~ receptors bind antigens directly then corecptors can translate a signal B cells are capable of making cell-surface B-cell receptors secreting soluble antobdy mlc at the same time Antigens Epitopes Antigen Recognition BCR Signal Transduction antigen : BCR and antibodies can be gen to recognize signal tduct by BCR is enhanced by crosslinking any substance that can generate an antibody any type of antigen in any 3D conform all antibodies have 2 antigen binding sites a molecule that is recognized by a B T cell receptor lock key mechanism 2 antibodies can be cross linked by 1 antigen epitope : enhances signal to cells part of antigen B cells can recognize any substance organic proteins chemicals sugars the mlclr surface that directly interacts w B T receptor TCR Recognition B T Cell Specificity TCR can only recognize peptide antigens presented by each B T cell makes a receptor of 1 single specificity MHC mlcs each B T cell makes different antibody receptors 8-24 aa peptides derived from larger prots one cell makes one type TCR are exclu cell-surface receptors (not secreted) all receptors on a cell are the same TCR made up of 2 mlcs : alpha beta each B cell makes a BCR specific for 1 unique epitope extracellular component · transmembrane region can be any mlc short cytoplasmic tail each T cell makes a TCR specific for 1 unique epitope interaction stabilized by CD4 CD8 BCRs TCRs recombined genes & Clonal Selection Theory Postulates of the Clonal Selection Theory BCRS TCRS are encoded by recombined genes - if infected w pathogen that one the preexisting 1) Each lymphocyte bears a single type of receptor with a hozumi tonegawa 1976 : cells recog unique specificity · the cell will be clonaly selected to , discov that genes that encode antibodies and ↳ participate in immune response 2) Interaction between a foreign molecule and a lymphocyte BCRs are located in various regions of the - the antigen will trigger a signal to make cell receptor capable of binding that molecule with high affinity genome and consist of V,D,J segments 2 the cloning expands they can & leads to lymphocyte activation differen into a variety of effector cells VDJ segments are brought tg by genetic recombination 3) The differentiated effector cells derived from an activated.to encode antibodies BCRs deletion : lymphocyte will bear receptors of identical specificity to anything that recognizes your body cells is deleted - Tak Mak and Mark Davis 1984 : prevents auto-immunity those of the parental cell from which that lymphocyte was clonal selection expansion : ~ discov the genes that encode TCRs leaves u w cells that not recog things you havent been exposed to derived & BCR TCR rearrangement occurs during lymphocyte ready to be activated 4) Lymphocytes bearing receptors specific for ubiquitous self development to generate a repertoire of antigen molecules are deleted at an early stage in lymphoid cell specificities - before cells encounter antigen development and are therefore absent from the repertoire of mature lymphocytes Clonal Selection Adaptive Immunity primary response : lag : T B cells w the exact specificity are rare must be clonaly selected slow secondary response : after infection resolves itself many more B T cells W same specificity