Clonal analysis of T cell unresponsiveness to alloantigens induced by neonatal injection of F1 spleen cells into parental mice.

Alloantigen-specific T cell precursors present in spleen cell populations obtained from parental mice that were rendered tolerant by the neonatal injection of F1 spleen cells were quantitated by clonal analysis, i.e., limiting dilution techniques. The results demonstrate that the frequencies for cytolytic as well as TCGF-producing (helper) and MAF-producing T cell precursors were dramatically reduced in tolerant spleen cell populations. The unresponsive state was antigen specific and could not be transferred in vitro in cell mixing experiments. Therefore, clonal deletion (or inactivation) would appear to represent a major mechanism for the observed tolerant state in this model system.