Immunization of normal human splenocytes in vitro to produce human monoclonal antibodies to cellular antigens.

We have obtained human monoclonal antibodies to polymorphic cell surface determinants by immunizing normal human splenecytomy in vitro to allogeneic cells. Splenocytes from young patients undergoing splenectomy secondary to traumatic injury are separated into T and B lymphocyte populations. The T lymphocytes are irradiated with 1500 rad to selectively inactivate T suppressors. Responder T and B cells are then recombined at a 1:1 ratio. Maximal IgM and IgG production is obtained when pokeweed mitogen and irradiated stimulator cells are added to the cultures. Stimulator cell specific antibody levels peak at day 7 of in vitro immunization, and fall thereafter. Fusion of the immunized splenocytes to a human fusion partner as early as day 4 results in hybridomas secreting antibodies to cellular antigens. Transformation by EBV, expansion and fusion of the immunized cell line also yield hybridomas secreting stimulator cell specific antibody.