91401 Lecture Notes - Lecture 5: B-Cell Receptor, Peanut Allergy, Allergic Rhinitis
Document Summary
Immunoglobulin e (ige) heavy chain: very low serum concentration (0. 002% of ig, 4 heavy chain c domains potent biological actions, provides immunity against helminths but also responsible for allergy. Eczema: sensitises mast cells to antigen by binding fcre. B cells express igm and igd e. g. serves as an antigen receptor on b cells. Class switching in the gc: b cells that enter the germinal centre receive signals from cytokines to undergo antibody isotype switching (first express igm) Isotype switching allows transmembrane expression & secretion of other isotypes (igg, iga, ige: cytokines are secreted by cd4+ helper t cells that are present in the light zone (called t follicular helper cells) Isotype switching allows a given v h exon to associate with different ch genes: antigen-dependent. Irreversible (deletional) dna recombination stimulated by external signals: heavy chain vh remains the same and light chain unaffected therefore antibody retains the same specificity for an antigen.
