Evidence for a mature B cell subpopulation in Peyer's patches of young adult xid mice

Peyer's patch (PP) and mesenteric lymph node (MLN) cell cultures from young adult X-linked immunodeficient (xid) CBA/N and (CBA/N X DBA/2) F1 male mice support primary anti-sheep erythrocyte (SRBC) plaque-forming cell (PFC) responses, which suggests that gut-associated lymphoreticular tissue (GALT) contains a normal B lymphocyte subpopulation. Further support for this was provided by the observation that PP cells from xid mice gave responses to both TI-1 and TI-2 antigens that were similar to the responses of PP cell cultures from normal mice. Spleen cell cultures from xid mice were unresponsive to SRBC and TI-2 antigens. Proof that GALT of xid mice contain mature B lymphocytes was provided by the demonstration of PP B cells that bear a low density of surface immunoglobulin M. When these cells were separated by flow cytometry and immunized with trinitrophenyl (TNP)- Ficoll in vitro, good anti-TNP PFC responses were observed. These results suggest that GALT of young adult xid mice contain mature B cells and may represent the origin for the mature B cell responses seen in aged xid mice.