CELL-INDUCED IG ALLOTYPIC SUPPRESSION IN MICE - BASIS FOR EMERGENCE OR TOLERIZATION, DURING THE PERINATAL-PERIOD, OF NATURAL T-CELLS SPECIFIC TO THE IGG2A(B) ALLOTYPE

We have previously described an anti-IgG2a(b) T cell activity in norma l Igh(a/a) mice. Their congenic partner at the Igh locus (Igh(b/b)) an d Igh(a/b) hybrids bred from them, do not display this T cell activity but express IgG2a(b). As these mice are supposed to possess the same genetic elements related to this potential T cell repertoire, only som atic selection mechanisms could be responsible for their different beh avior. In this study, we investigated the basis for the emergence (in Igh(a/a) mice) or tolerization (in Igh(b/b)-congenic mice and in Igh(a /b) hybrids) of these natural anti-IgG2a(b) T cells. Stringent perinat al B cell deprivation in Igh(b/b) and Igh(a/b) mice resulted in the em ergence of anti-IgG2a(b) T cells, as these individuals could be subjec ted to autoimmune, T cell-mediated IgG2a(b) suppression. Furthermore, the acquisition of anti-IgG2a(b) T cell activity was drastically reduc ed in Igh(a/a) mice, perinatally exposed to IgG2a(b); thus, the presen ce of this allotype leads to tolerization of these specific T cells.