Microbiology and Immunology 2500A/B Lecture Notes - Lecture 5: Memory B Cell, Follicular B Helper T Cells, Immunoglobulin D

• School: Western University
• Department: Microbiology and Immunology
• Course: Microbiology and Immunology 2500A/B
• Professor: John Mc Cormick

Document Summary

Main role: help eliminate extracellular pathogens & inactivate soluble proteins (eg. toxins, allergens) Most common response is against protein antigens (ie. pathogen, allergen, toxin) Can also respond to non-protein antigens unlike t cells. Antibody: soluble ig molecule secreted by plasma cells. Class defined by differences in heavy chain constant region. Provides flexibility (eg. igg/iga has higher epitope affinity than igm w/ no. Develops in bone marrow & enters into circulation @ naive b cell. All naive cells express igm & igd bcrs on surface. Naive b cells circulate through slt looking for specific antigen epitope. If activated by specific epitope: b cell immunity initiates: binds protein epitope & endocytoses. Lysosomal degradation allows exogenous peptide to be presented on mhc class ii: effector tfh cell binds presented peptide & secretes il-2. Tells both cells to undergo clonal expansion. Thus t cell immunity must occur to initiate b cell immunity against protein antigen.