B-1 cell-derived monoclonal antibodies and costimulatory molecules

B-1 cells represent a specialized subset of B cells that are distinct from conventional B cells. The exact role of B-1 cells is still under investigation. The purpose of this study was to characterize B-1 cell-derived monoclonal antibodies and to examine the expression of costimulatory molecules (MHC class, B7.1 and B7.2) by splenic and peritoneum-derived (PerC) B cells to a different antigenic stimulation.

As presentation of antigens to T lymphocytes by B-1 cells is difficult to evaluate at the human level, we used inbred mice. We established hybridoma producing B-1 cell-derived monoclonal antibodies to characterize them to the exogenous and endogenous antigens. Expression of MHC Class, B7.1, and B7.2 by splenic and PerC B cells to a different antigenic stimulation was also evaluated by flow cytometric analysis.

We established two B-1 cell-derived clones demonstrating similarity in their manner of polyreactivity and in terms of their dose-saturable response to the multiple antigens. Splenic and PerC B cells revealed a similar pattern of MHC expression. However, B7.1 and B7.2 were expressed higher in both B cells, while these were more pronounced in PerC B cells.

B-1 cell-derived monoclonal antibodies were characterized as polyreactive in nature to a panel of exogenous and endogenous antigens. Splenic and PerC B cells revealed a distinctive pattern in their mode of expressing costimulatory molecules when challenged by exogenous or endogenous antigens.