Characterization of phosphorylcholine- (PC) specific IgE-B cells in CBA/N or (CBA/N x BALB/c)F1 male mice.

Surface immunoglobulin isotype of precursors for PC-specific IgE response in CBA/N or NBF1 male mice was studied. Immunization of CBA/N or NBF1 male mice, which had been lethally irradiated and reconstituted with KLH-primed syngeneic spleen cells, with PC-KLH induced the PC-specific IgE, but not the IgM, response. Depletion of mu-bearing cells from KLH-primed spleen cells completely abolished the induction of the anti-PC IgE response. Depletion of T15 idiotype-bearing cells with anti-T15-coated dishes also abrogated the anti-PC IgE response in NBF1 male mice. Mice that were transferred with delta- or epsilon-bearing cell-depleted cell populations did not show the anti-PC IgE response on day 14, but they showed the anti-PC IgE response on day 21. These results indicated that PC-specific IgE-producing cells in CBA/N mice, which were defective in the anti-PC IgM response, were derived from PC-specific mu-bearing cells, and direct precursors bore mu, delta, and epsilon on their surface.