Human anti-tetanus antibody response in vitro: Autologous and allogeneic T cells provide help by different routes

Human B cells will make anti-tetanus antibody in vitro in the presence of antigen and T cells. These T cells may be autologous, but allogeneic T lymphocytes function equally well provided they are first irradiated. The allogeneic cells provide help by a different route. Co-culture of allogeneic cells produces a degree of polyclonal activation of B cells and a much higher level of IgM anti-tetanus antibody than autologous cultures. Depletion of tetanus toxoid or alloantigen-reactive T cells by ³H-thymidine suicide indicates that in autologous cultures help for anti-tetanus toxoid antibody production is provided by antigen-reactive T cells while in allogeneic cultures antibody production is dependent on the presence of alloreactive T cells. The implications for assessing human T and B cell function are discussed.