The response of lymphocytes from non-immunized humans to antigen-antibody complexes.

The stimulatory effect of antigen–antibody–complement complexes on cultured normal human peripheral blood lymphocytes was studied. The donors of the cells had not been sensitized to the antigens used. Two antigens were used: flagellar antigen of B (SPB) and bovine serum albumin (BSA), with their respective antibodies prepared in rabbits. The addition of such antigen–antibody aggregates to the cultures stimulated the lymphocytes as determined by morphological changes and increased uptake of [C]thymidine into DNA. Peak of stimulation was observed after 5–6 days of culture incubation. The stimulation appeared to be complement dependent. The lymphocytes showed no response either to the antigen alone or to anti-SPB. When BSA–anti-BSA was centrifuged, most of the stimulatory activity was found in the supernate. The most likely explanation of this stimulation is injury to lymphocyte membranes, possibly from a non-specific attachment of immune complexes to them. A similar mechanism of membrane injury may underlie reactions to all non-specific stimulants, and possibly also to specific antigens to which the cell donor is sensitized.