Immunoresponses to Neisseria meningitidis epitopes: primary versus secondary antiphosphorylcholine responses.

Specific antiphosphorylcholine immune responses were found to be elicited by different Neisseria meningitidis group B M986 preparations. Our results suggest the functional presence of phosphorylcholine in the bacteria. The immune responses, mostly immunoglobulin M, were measured with a plaque-forming cell assay. The secondary phosphorylcholine-specific immune response induced by intact meningococci was significantly lower than the primary phosphorylcholine-specific immune response induced by the same antigens. This suppression is priming time dependent and does not represent an early switching to the expression of other classes of immunoglobulins.