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Immuno Lecture 5:6 Notes.docx

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Health Sciences
Jonathan Bramson

Lecture 5- Adaptive Immunity I Innate vs. Adaptive  Innate immunity acts immediately and adaptive takes time  Both systems are always talking to eachother  Key Differences: Secondary Response o Innate= will always respond the same way o Adaptive = will give you a faster AND stronger response the second time  Cells in the adaptive immunity= B-cells and T-cells o B and T cells have different receptors than the innate (which has pattern recognition properties) o B and T= have diverse receptors o Antigens= something that can bind specifically with an antibody (BUT, note in the case of T-cells= will recognize only part of the antigen o E.g. of Antigens= carbohydrates, lipids, proteins B-Cell Receptors  B-cell receptor= the anitbodies attached to the B-cell surface  Antibodies= technically formed when released from the B-cell o ***KNOW HOW TO DRAW AN ANTIBODY  Domain 1: Variable region=bind the antigen  Domain 2: Constant region= effector region= makes immune system responds  1+2 domain= Composed of TWO heavy chains (in the middle) and two light chains o Act to opsonize (i.e. coating pathogen) o Act to neutralize toxins formed by pathogen (prevents toxins to act) o Act to activate the complement pathway (recall: classical pathway) T-cell Receptors  Can only recognize the antigen in the context of MHC (MHC bound with peptide [part of antigen])  Receptor = embedded region= constant and the portion furthest from membrane= variable  MHC Genes = Called HLA genes (Human leukocyte antigen)  MHC Class 1 o Found in all nucleated cells (hence, not RBC) o Endogenous (i.e. deals with any protein degraded in the cytosol= cytosolic protein) o α chain and β microglobulin 2 o Genes= 1 chain HLA-A,-B,-C  MHC Class 2 o Found on Antigen Presenting Cells (APC) o Exogenous (after phagocytosis= extracellular fragments are degraded and presented by MHC II) o α chain and β chain (not the same α chain as seen in MHC I) o Genes= 2 chains= HLA-DR,DP-DQ *** NOTE= VARIABILITY IN GENES (i.e. polymorphisms) LEADS TO EVERYONE HAVING DIFFERENT MHC RECEPTORS!!! ***NOTE: MORE ABUNDANT, PROXIMITY AND AFINITY= more presentation seen in the MHC ***NOTE: WITHOUT MHC/DIFFERENT MHC= MAKES IT HARD FOR T-CELLS TO RECOGNIZE= SKIN GRAFT REJECTION! Lecture 6- Adaptive Immunity II MHC Class I  Has one α chain that is supported by β2microglobulin  α 1nd α 2omains form binding cleft (but still on the same chain)  α 3omain= is embedded= acts as a supporting structure  Bind 8-10 aa long peptide AND restricted interaction at the ends of the peptide MHC Class II  α chain and β chain form the binding cleft =
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