ENHANCEMENT OF SPECIFIC IMMUNOGLOBULIN PRODUCTION IN SCID-HU-PBL MICEAFTER IN-VITRO PRIMING OF HUMAN B-CELLS WITH SUPERANTIGEN

Priming of human mature B cells in vitro with staphylococcal enterotox in A (SEA) prior to transplantation of the B cells into severe combine d immunodeficiency (SCID) mice, together with human T-helper cells, re sulted in higher and more uniform concentrations of serum IgG in the m ice. This indicated that a large number of B cells had become activate d, which was supported by the finding that SEA priming resulted in pro duction of immunoglobulin displaying a more normal kappa/lambda. ratio than was obtained in the absence of SEA priming. However, IgM concent rations were not affected by SEA priming. Immunization of mice, transp lanted with SEA-primed B cells, with both primary and secondary antige ns resulted in a high specific IgG response to both types of antigen. The elevated levels of specific antibodies were not merely the consequ ence of an unspecific stimulation of B cells caused by SEA, as the rat io of specific antibody to total IgG was much higher in animals receiv ing SEA-primed B cells. Thus, a co-operative effect on immunoglobulin production of stimulating B cells via surface immunoglobulin and help delivered by SEA-activated T-helper cells was indicated. A specific an tigen-dependent IgM response to a secondary antigen was observed as we ll, but was, in contrast to the IgG response, not influenced by SEA pr iming of B cells. No IgM antibodies with reactivities to the primary a ntigens were detected in the SCID sera at any time-point after immuniz ation. The results thus indicate that SEA might replace T-cell epitope s in antigens and efficiently recruit an abundance of T-cell help to B cells, resulting in enhanced production of specific IgG antibodies.