Intrathymic elimination of Mlsa-reactive (V beta 6+) cells during neonatal tolerance induction to Mlsa-encoded antigens.

Abstract
The cellular basis of neonatally induced T cell tolerance has been investigated in a model system in which usage of a particular TCR V.beta. segment (V.beta.6) is strongly correlated with reactivity to antigens encoded by the Mlsa genetic locus. Expression of V.beta.6 by peripheral T cells was virtually abolished in BALB/c (H-2d, Mlsb) mice rendered neonatally tolerant to DBA/2 (H-2d, Mlsa) lymphoid cells, whereas control V.beta.8-bearing T cells remained at near normal levels. Further analysis revealed that elimination of V.beta.6+ T cells occurred in the thymus of neonatally tolerant mice and could not be explained by receptor modulation or T cell chimerism. These data thus support the clonal deletion model of tolerance induction.