Question

At a genetic level, how does the human immune system recognize potentially billions of different antigens?

Answer 1

Immune system is able to synthesize literally infinite varities of antibodies. This is possible by

1. DNA recombination which occurs in class switch recombination.The exons which code for variable region are split into small segments and are rearranged. this results in production of antibody of different variety.

2.Imprecision in the joining of the V,D and J genes is also considered one of the reasons for antibody diversity

3.Immunoglobulin class switching. Plasma cells which are normally producing IgM switch to produce IgG.