Chapter 29 : Functional Assays for B Cells and Antibodies

Abstract:

The primary cells of the adaptive immune system are T cells, B cells, and natural killer cells. These lymphocytes assist the host in eliminating both intracellular pathogens (T cells and NK cells) and extracellular pathogens (B cells) through B cell-T cell interactions, as well as interactions with other cells and molecules of the innate immune system. B cells recognize foreign antigen by the B-cell receptor (BCR), a membrane-bound immunoglobulin generated through a complex genetic recombination process (1). The BCR recognizes conformational protein antigens as well as nonprotein antigens. Two types of B cells have been described based on expression of cell surface molecules and function. B1 (CD5+) B cells are thought to be a more “natural” type of B cell which respond to T-cell-independent forms of antigen (i.e., bacterial polysaccharides) (2, 3). B2 B cells respond to T-cell-dependent antigens, such as the classic protein antigens tetanus and diphtheria toxoids. Both classes of B cells respond to BCR binding of antigen by proliferation, differentiation into antibody-secreting plasma cells, and formation of memory B cells.