The influence of N-[4-(5-nitro-2-Furyl)-2-thiazolyl]formamide and phenacetin on the immune status in male Fischer rats.

The effect of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANTF) and phenacetin on the immune status of Fischer rats was determined utilizing the spleen plaque and phytohemagglutinin blastogenesis assays 6, 10, and 15 weeks after administration at doses of 0.2 per cent and 0.535 per cent, respectively. Azathioprine (0.02 per cent of the diet) was tested as a known immunosuppressive chemical for comparison, and a negative control group, fed a control diet without added chemicals, was also tested. Immunosuppression was shown in the rats receiving azathioprine at all times by both assays, whereas in FANFT-fed rats immunosuppression was greater than in the control group (not statistically significant). Results from rats fed phenacetin were not significantly different than those of the control group. These results show that immunosuppression does not occur in rats administered phenacetin for up to 15 weeks, nor in FANFT-induced bladder carcinogenesis at the time of reversible bladder mucosal hyperplasia (6 weeks), or when the mucosal lesions have become irreversible, non-invasive carcinomas (10 and 15 weeks).