Suppressive activities involving T-B and T-T cell interactions are importan
t to maintain immune system homeostasis. Negative control of IgG2a(b+) B ce
lls by anti-IgG2a(b) T cells derived from Igha mice has been well documente
d. Nevertheless the real contribution of anti-IgG2a(b) T cells, endogenousl
y matured in Igh(b) mice, in controlling IgG2a(b+) B cell function has neve
r been investigated. We previously generated anti-IgG2a(b) TCR-transgenic m
ice and showed that transgenic T cells were not deleted in the thymus and t
hat they were responsible for a complete and chronic IgG2a(b) suppression.
Here we show that T cells expressing high density of anti-IgG2a(b) TCR were
positively selected in the thymus with a higher efficiency in animals expr
essing IgG2ab, reached peripheral lymphoid organs and negatively controlled
IgG2a(b) serum levels. Moreover, anti-IgG2a(b) T cells transgenic for the
single TCR beta chain, thus undergoing normal alpha rearrangements and norm
al processes of selection, also reached the periphery and suppressed IgG2a(
b). Interestingly, concentration of IgG2a(b) in serum inversely correlated
with the peripheral frequency of Ig-specific T cells. Finally, T cells able
to suppress IgG2a(b) were obtained from Ighb non-transgenic mice, indicati
ng that anti-gamma 2a(b) T cells are naturally present in the periphery of
Ighb animals. We propose that IgG2a(b)-specific T cells contribute to deter
mine IgG2a(b) serum levels in Ighb mice.