Analysis of the B cell subpopulations influenced by allogeneic effect factor. I. MHC restricted enhancement of b cell responses to thymic-independent antigens, types 1 and 2, in normal and CBA/N mice.

The ability of allogeneic effect factor (AEF) to enhance the in vitro antibody responses of murine T cell-depleted B cell populations to thymic-dependent (TD) antigens also occurs with thymic-independent (TI) antigens. AEF significantly enhanced the in vitro antibody responses of normal T cell-depleted spleen cell populations to both 2,4,6-trinitophenylated Brucella abortus (TNP-BA), a TI type 1 antigen, and 2,4,6-trinitrophenylated aminoethylcarbamylmethyl-Ficoll (TNP-Ficoll), a TI type 2 antigen. The enhancing activity of AEF on TI responses was analyzed further in immune-defective CBA/N mice that possess only Lyb-5- B cells, and thus fail to respond to TNP-Ficoll, but do respond to TNP-BA and sheep red blood cells (SRBC). AEF was able to reconstitute the in vitro antibody responses of CBA/NT cell-depleted B cell populations to SRBC and to augment the T cell-depleted response to TNP-BA. These data suggest that AEF can enhance the activity of both Lyb-5+ as well as Lyb-5- B cells in their responses to both type 1 and type 2 TI antigens, and to the TD antigen SRBC. This enhancing effect of AEF on the TD and TI responses was MHC restricted for both Lyb-5+ as well as Lyb-5- spleen cells.