Effect of cytokines on 5-fluorouracil-mediated immunosuppression

The effect of cytokines on 5-fluorouracil-mediated suppression of antibody response to arsanilic acid-bovine gammaglobulin (ARS-BGG) in high- and low-responding strains of mice was determined. Single i.v. injections of 5-fluorouracil strongly inhibited both primary and secondary antibody responses. The high-responding strain was found to be more sensitive to 5-fluorouracil. Restoration of suppressed IgG antibody responses to ARS-BGG was achieved in vitro by addition of either rIL-4, or rIFN gamma to the culture medium. Similarly, IgA titers recovered following the addition of exogenous rIL-5. The inhibition of IgM production, however, was not influenced by any of the cytokines tested. No significant differences were observed between experimental groups injected with antigen before or after 5-fluorouracil application. Our results suggest that the immunosuppression caused by 5-fluorouracil treatment can be abrogated by the addition of cytokines.