Protective activity of thymosin against opportunistic infections in animal models.
Animal models for opportunistic infections were developed by using mice immunosuppressed by 5-FU. These mice were susceptible to various microorganisms, while normal mice had greater tolerance to such microbial infections. In these models, thymosin alpha 1 was found to protect mice against lethal infections with Candida albicans, Listeria monocytogenes, Pseudomonas aeruginosa, and Serratia marcescens when it was administered during 5-FU treatment prior to the infections. Thymosin alpha 1 was effective in some infections at 0.4-400 micrograms/kg/day IP, about 1/100 of the dose required for thymosin fraction 5. Activity was also demonstrated against L-monocytogenes and Ps. aeruginosa by counting the viable bacteria in the liver after infection. The protective activity against Candida, elimination of which macrophages were essential, was abrogated by anti-thymocyte serum and/or carrageenan, indicating that thymosin alpha 1 serves to maintain the functions of macrophages by reducing the damage to T cells by 5-FU. On the other hand, the activity against Pseudomonas infection was not affected by anti-thymocyte serum or carrageenan. It is probable that thymosin alpha 1 also exerts its effect on neutrophils without participation of T cells and macrophages.
D000818:Animals; D002176:Candida albicans; D002177:Candidiasis / Q000517:prevention & control*; D004334:Drug Administration Schedule; D004756:Enterobacteriaceae Infections / Q000517:prevention & control*; D005472:Fluorouracil / Q000008:administration & dosage / Q000494:pharmacology*; D008089:Listeria monocytogenes; D008088:Listeriosis / Q000517:prevention & control*; D051379:Mice; D008815:Mice, Inbred Strains; D011552:Pseudomonas Infections / Q000517:prevention & control*; D012706:Serratia marcescens; D013947:Thymosin / Q000008:administration & dosage / Q000627:therapeutic use*; D013951:Thymus Hormones / Q000627:therapeutic use*
D013951:Thymus Hormones; D013947:Thymosin; D005472:Fluorouracil