BIOC39H3 Lecture Notes - Lecture 19: Mhc Class Ii, Severe Combined Immunodeficiency, Hyper Igm Syndrome
8 Apr 2015
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Document Summary
Primary: inherited defects in genes for components of the immune system. Secondary: not due to defective genes, but to environmental factors such as immunosuppressive drugs. Dominant: inherit one functional, one dysfunctional allele. No gene rearrangements in b cell & t cells. The defect in xla is in bruton"s tyrosine kinase (btk: contributes to intracellular signaling from bcr and is necessary for the growth and differentiation of pre-b cells. Males inheriting an x chromosome with a mutant btk gene that does not produce a protein therefore lack mature b cells. Women with one functional and one nonfunctional copy of the btk gene are themselves healthy, but they pass xla on to half their male children. Patients are treated with monthly injections of gammaglobulin, an antibody containing preparation made from the plasma of healthy blood donors. Interaction of cd40 ligand on activated t cells with b cell cd40 receptor stimulates b cell activation, development of germinal centres, and isotope switching.
