A chemical approach to the mechanism of B-lymphocyte activation. II. The pure presentation of haptens does not inactivate B lymphocytes.

Dinitrophenyl (DNP)-lysine-polymethylmethacrylate and DNP-cellulose conjugates do not irreversibly inactivate anti-DNP antigen-sensitive cells, regardless of the dose (up to 10 mg) or persistence of the stimulation (up to 2 weeks). Since these conjugates constitute pure hapten presentations, it is concluded that the pure hapten presentation to B lymphocyte does not irreversibly inactivate them. When murine spleen cells are cultured with Escherichia coli lipopolysaccharide (LPS) and (non-immunogenic) DNP-lysine-polymethylmethacrylate or (non-immunogenic) DNP-cellulose conjugates, an anti-DNP immune response occurs. However, replacement of DNP-lysine-polymethylmethacrylate with polymethylmethacrylate, or DNP-cellulose with cellulose, also results in a similar anti-DNP response. It is consequently concluded that the anti-DNP responses are entirely elicited by LPS, the hapten Dnp being inoperative. The anti-DNP response elicited by DNP-Ficoll is, upon exhaustive testing, carrier-dependent. This implies that the mechanism of DNP-Ficoll immunogenicity is not two cooperative signals passed on to B lymphocytes via the hapten DNP. These results argue against any two-signal model of B-lymphocyte activation.