N-[4-(5-Nitro-2-furyl)-2-thiazolyl]
acetamide (
NFTA) administered at 1000 ppm in diet to mice for 12 weeks induced a high incidence of
lymphocytic leukemia. Effects of
NFTA on antibody-mediated immunity and cell-mediated immunity of BALB/c mice were studied using the spleen plaque assay for detection of
immunoglobulin M-producing cells and the graft-versus-host (GVH) reaction, respectively.
NFTA suppressed both responses. With the spleen plaque assay, the number of antibody-forming cells (AFC) to sheep red blood cells was significantly less than in unmedicated, control mice after treated mice received
NFTA at 1000 ppm for 6 days. The GVH reaction was not suppressed at 21 days, but was severely suppressed at 70 days, prior to the histological appearance of
leukemia. Effect of dose was studied by administering
NFTA at 100, 250, 500, and 1000 ppm of diet for 13 to 14 weeks and then determining the response in the spleen plaque assay and GVH reactions. The ratio of AFC/spleen of
NFTA-treated groups to AFC/spleen of an unmedicated control group, at the above specified doses, was 0.86, 0.22, 0.33, and 0.54 in ascending dosage order beginning with 100 ppm. For the GVH reaction, the suppression of the cell-mediated immunity was directly proportional to the dose of
NFTA. Suppression of the antibody-mediated immunity in relation to the induction of
leukemia at 28 weeks was studied by feeding
NFTA at 500 ppm for 14 weeks, followed by unmedicated diet for 14 weeks. During the 11th week, mice were immunized with SRBC; 5 days later the spleens were removed and the spleen plaque assay was performed. Eight of 18 mice fed
NFTA developed
leukemia. The number of AFC/spleen was 78 X 10(3) +/- 34 for those with
leukemia and 68 X 10(3) +/- 24 (p greater than 0.5) for those without
leukemia, compared with 170 X 10(3) +/- 74 for the control mice (p less than 0.01 for both groups, compared with controls). A closely related carcinogenic nitrofuran, N-[4-(5-nitro-2-furyl)-2-thiazolyl]
formamide, did not suppress the antibody-mediated immunity response measured during the 11th week of administration.