Thymus-dependency of the immune response of mice to a primary infection with the nematode Trichuris muris

Adult mice which had been thymectomized, irradiated and given stem-cell protection were incapable of making a self-cure response to a primary infection with the nematode Trichuris muris. The capacity to mount a self-cure response was restored by the injection of 2·5 × 10⁶ mesenteric lymph node lymphocytes or by 2·5 × 10⁸, but not 2·5 × 10⁷, thymocytes. Restoration of the ability to respond to sheep red blood cells was achieved with all three cell injections. Suppression of the immune response was also achieved by injection of ALS during the second week of infection and at intervals thereafter. The results of thymectomy and ALS treatment show that immunity to T. muris is dependent upon the presence of an intact thymus and thymus-dependent cell population.