Nuclear Medicine Technology and Other Health Applications Project Title: Lymphocytopoiesis and Transplantation Immunology 15, Relationship to Other Projects: (Cont'd,) RX-01-03-(d) renal transplantation. Other clinical ECIB studies are those of: Anderson, University of Copenhagen, Lajtha, Manchester, England; ‘and Mauer, Children's Hospital, University of Cincinnati, Gowans and associates, Sir William Dunn School of Pathology, Oxford; Morris et al, University of CANBERRA, Australia; Lance and associates, Northwick Park Hospital, Harrow, England; Everett and associates, University of Washington, and Waksman and associates at Yale University study cell proliferation and migration in lymphopoietic systems and the relationship to immunologic reactions. 16, Technical Progress in FY 1973: ™~ + Intra-arterial labeling of the thymus with tritiaced thymidine in calves has shown extensive migration of thymocytes to the gut-associated tissues, lymph nodes, and spleen, Within lymph nodes, the migration first to the paracortex is followed by migration to the outer cortex and into the medulla, have any, to date, Thymic cells are not found in germinal centers nor been found in the bone marrow. In the spleen, labeled cells are first seen in the marginal zone; migration follows into the dense white cortex and into the red pulp of thespleen, Preliminary studies suggest that thymic migrants divide rapidly and are undetectable after 96 hours, The life span of the migrants is under study, Brookhaven results, based on morphological and autoradiographic studies of thymic cell migration and proliferation in newborn mice, conflicted with data obtained elsewhere utilizing cytotoxicity of anti- bodies against the thymic alloantigen @. While at the University of Bern, Dr. Chanana restudied the problem employing indirect immunofluorescent techniques directed against natural 9 surface alloantigen, These studies conclusively demonstrated a major migration from thymus to the gut- associated lymphoid tissue, lymph nodes, and spleen in the first five postnatal days. The magnitude of the migration of ® x cells from the thymus of the mouse to gut was unexpected--over 90% of the cells in Peyer's patches and mesenteric lymph nodes of 4-day old mice were 9 positive, These results fully support earlier studies in calves on migration from thymus to peripheral tissues using tritiated thymidine and thymic specific antigen as markers; also the FY 1972 studies of Joel on of tritiated thymidine labeled cells from the thymus of the migr id post is p gi mouse. The assertion chat the gut associated lymphoid tissue wily a bone marrow dependent organ must therefore be in doubt, (See Continuation Sheet) 1419224 RX-71