The role of B/T costimulatory signals in the immunopotentiating activity of neisserial porin

A T cell-dependent immune response to group C meningococcal capsular polysa ccharide (CPS) can be elicited when CPS is conjugated to the class 3 neisse rial porin (CPS-porin). Treatment of CPS-porin-immunized mice with B7-2 blo cking monoclonal antibody (MAb) caused a dramatic reduction in the CPS-spec ific IgG response, treatment with anti-B7-1 MAb had no effect, and concurre nt blockade of B7-1 and B7-2 resulted in a synergistic abrogation of the CP S-specific IgG response while the CPS IgM response was unaffected. Anti-CD4 0L MAb treatment caused a significant reduction of both CPS-specific IgG an d IgM levels. In contrast, blockade of CTLA4 interactions resulted in incre ases in both CPS IgG and IgM responses in CPS-porin-immunized mice. These d ata support the hypothesis that the ability of neisserial porins to improve the immune response to poorly immunogenic antigens (e.g., polysaccharides) is related to porin-induced increases in B7-2 expression on antigen-presen ting cells and enhanced B/T cell interactions.