[Effect of traxanox on antibody formation in C57BL/6 mice]

C57BL/6 mice, lower responders to sheep red blood cells (SRBC), were intraperitoneally immunized with 5 X 10(8) SRBC on day 0. Traxanox (10 and 30 mg/kg) administered orally on days 0 and 1 potentiated the production of spleen- and thymus-rosette forming cells (RFC) assessed on day 7. The production of hemolytic plaque forming cells (HPFC) to SRBC in the spleen of the syngeneic recipient mice assessed on day 4 was inhibited by the transfer of spleen-RFC obtained from the vehicle-treated donor mice, but not by that obtained from the traxanox (30 mg/kg)-treated donor mice. The same results were obtained in the thymectomized-recipient mice. The activity of the spleen-RFC obtained from the vehicle-treated donor mice was abolished by treatment with anti-Thy 1.2 or anti-Lyt 2.2 antibody and complement. On the other hand, the activity of the spleen-RFC obtained from the traxanox-treated donor mice was abolished by treatment with anti-Lyt 1.2 antiserum and complement. Traxanox (3 and 30 mg/kg) also caused the induction of the Thy 1.2-positive RFC in the spleen of the thymectomized mice. These results suggest that traxanox has a capacity to potentiate the immune responses to SRBC in C57BL/6 mice by the induction of Lyt 1.2-positive cells (helper T cells).