Abstract
The number of spleen-rosette forming cells (RFC) and thymus-RFC was assayed on day 4 after immunization with 5×108 sheep red blood cells (SRBC) in BALB/c mice. The number was decreased significantly by oral administration of cyclophosphamide (20 mg/kg) on days −1 and 0. The decrease in spleen-RFC and thymus-RFC by the pretreatment with cyclophosphamide was significantly restored or had a tendency to be restored by traxanox at doses of 3 and 30 mg/kg (p.o.). In addition, traxanox (30 mg/kg, p.o.) protected the reduced number of RFC in mice treated with cyclophosphamide (3 mg/kg, p.o.). Traxanox (30 mg/kg, p.o.) restored the decreased number of spleen-RFC and thymus-RFC in mice pretreated with dexamethasone (0.1 mg/kg, p.o.), and protected the decrease in the RFC in mice treated with prednisolone (10 mg/kg, p.o.). Also, phagocytosis of SRBC by the spleen adherent cells obtained from mice treated with dexamethasone (0.1 mg/kg, p.o.) was inhibited markedly in comparison with that by the spleen adherent cells of untreated mice. The transfer of the spleen adherent cells treated with dexamethasone into syngeneic recipient mice had no effect on the number of spleen hemolytic plaque forming cells (HPFC). On the other hand, the inhibition of phagocytosis of SRBC by spleen adherent cells of mice pretreated with dexamethasone was restored by the addition of traxanox (10 and 30 μM). The transfer of the spleen adherent cells treated with traxanox resulted in an increase in HPFC number. Traxanox (30 mg/kg, p.o.) protected the decrease in spleen-RFC and thymus-RFC in mice treated with indomethacin (1 mg/kg, p.o.) or acetylsalicylic acid (300 mg/kg, p.o.). Traxanox (3 ?? 30 mg/kg, p.o.) restored the decreased number of HPFC, spleen-RFC and thymus-RFC in mice pretreated with carrageenan (0.03 mg). The suppression of phagocytosis of SRBC by spleen adherent cells was restored by the treatment with traxanox (3 and 30 μM). The transfer of the spleen adherent cells treated with traxanox also resulted in an increase in HPFC count. These results strongly suggest that traxanox restores the artificially suppressed immune responses via macrophages.
