T dependent and T independent antigens
B cells require T cell "help" in order to produce antibodies to most antigens. Specialized antigen-specific T lymphocytes bind to Ag and B cells, activating them to secrete soluble B cell growth and differentiation factors. Ags that require T cell help for B cell responses are T dependent antigens. B cells do not require T cell help to respond to some antigens (usually long chain polysaccharides). These are T independent antigens.