Mechanism of neonatal idiotype suppression. I. State of the suppressed B cells.

Neonatal BALB/c mice, given small amounts of an anti-idiotype serum directed against the TEPC-15 idiotype, are chronically unresponsive to immunization with PC antigens. These mice recover from suppression slowly over a period of 10 mo, and their response is not of TEPC-15 idiotype. However, the PC-specific precursors, as analyzed by the splenic fragment culture technique, in 8-mo-old suppressed mice are normal with respect to their frequency and idiotype dominance. Furthermore, the PC-precursors in neonatally suppressed BALB/c are sensitive to tolerance induction, as are precursors from neonatal liver and spleen cells. When chronic suppressed mice are immunized with a novel TI-1 antigen, PC-LPS, shown to stimulate immature PC-specific precursors, their response to PC is 80% of TEPC-15 idiotype, whereas their response to a TI-2 PC antigen and to a TD PC antigen is not TEPC-15 dominant. These results indicate that the TEPC-15 positive B cells in neonatally idiotype suppressed mice are in a state of immaturity that resembles the developmental characteristics of normal neonatal BALB/c mice.