Reduction of syngeneic tumor growth by an anti-I-J-alloantiserum.

Highly significant suppression of the growth of S1509a and Sa-I syngeneic sarcomas was observed in A/J mice following daily intravenous injections of 2 microliter of anti-I-Jk alloantiserum. This effect persisted as long as the anti-I-Jk serum was administered (day 15), In contrast, a control anti-I-Js serum had no discernible effect on the growth of the S1509a tumor. The inhibitory activity of the anti-I-Jk serum on the growth of the tumor was absorbed specifically by B10-BR spleen cells bearing I-Jk determinants. In other experiments, we established that A/J mice treated with anti-I-Jk serum, according to the protocol described above, are no longer a source of tumor-specific suppressor cells for adoptive transfer into immune tumor-bearing recipient mice. We conclude that anti-I-Jk serum inhibits tumor growth in A/J mice by abolishing tumor-specific suppressor activity.