Abstract
Summary
1. Passage leukemia virus A of Gross produced leukemia in 15 of 22 virus-injected intact Z mice, 0 of 17 virus-injected thymectomized, and 2 of 20 virus-injected thymectomized Z mice given one lobe of normal thymus from uninjected donors of the same strain. 2. Thymuses of virus-injected mice removed at thymectomy, when implanted in 19 uninjected thymectomized adult Z mice, produced 2 lymphomas in the grafts. 3. Virus was found by bioassay to persist in tissues of virus-injected thymectomized non-leukemic Z mice sacrificed at 8 to 9 months of age. 4. In similar experiments in AK/Z mice, leukemia occurred in 14 of 15 virus-injected intact mice, 4 of 25 virus-injected thymectomized, and 24 of 44 virus-injected thymectomized AK/Z mice given normal thymus grafts from young AK and Z donors. 5. Bioassays were performed for immunogenetic character of 22 leukemias and tumors arising in thymic grafts on virus-injected thymectomized AK/Z mice. AK, Z and AK/Z recipients were used with the following results: a) 3 leukemias failed to grow in any recipients. b) In 8 cases, grafts took in AK/Z only (excluding those with uncertain typing); in 4 cases, in AK and AK/Z mice; and in one case in Z and AK/Z recipients. 6. These data indicate that a thymic factor, other than cell, supplied by normal thymus grafts may carry to completion viral leukemogenesis inhibited by removal of the thymus.
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