The effects of thymosin on bacterial infections in normal mice
Normal mice treated with thymosin before a lethal challenge of bacteria show a more prolonged survival than controls. Thymosin treatment the same time as challenge offers no protection. Thymosin treatment after a lethal challenge not only does not offer protection but also causes deaths, due to the bacterial infection, to occur faster. Continuous thymosin treatment after challenge neither enhances death rates further, nor offers protection to mice treated with th3miosin at the time of challenge or mice treated with th5nnosin after challenge. However, continuous thymosin treatment after challenge does increase protection of mice treated with thymosin before challenge. The protective and suppressive effects of thymosin seem to be time dependent and antigen dependent since the suppressive effects of thymosin treatment before, at the same time, or after a sublethal dose of antigen diminish over time. However, thymosin treatment longer than 24 hours before challenge offers the protective effects. It is postulated that the effects of thymosin are regulated through helper and suppressor T cells. This is the first in vivo demonstration of protection and suppression, due to the administration of th3miosin, in normal mice against bacterial infection. The suppressive aspect of thymosin stresses an urgent need for further experimentation before thymosin is used for prophylaxis in the cattle industry.