Nuclear Medicine Technology and Other Health Applications Project Title: Lymphocytopoiesis and Transplantation Immunology 14. Scope: (Cont'd) the changes during depletion and repletion, and the changes of allograft immunization. RX-O01-03-(d)_ in the course Labeling of thymocytes with tritiated thymidine via intra-arterial cannulae which has provided much information about the pattern and magnitude of T cell migration in calves will be used to gain more information on the fate and iife span of T cell migrants. The magnitude of migration from the thymus is studied also by observing the natural marker of T cells, the alloantigen 8.. mouse 9 + T cells The large postnatal migration of to the intestinal lymphoid tissues has been correlated with postnatal population of gut by bacteria, suggesting that the migratory stimulus may be from bacterial antigens. This will be investigated by studying T cell migration into the Peyer's patches and gut lumen using sterile and contaminated exteriorized intestinal loops. The long term study of tritiated thymidine labeled DNA and cell turnover is complicated by the fact that the tritiated thymidine is reutilized. However, in tne lymph node there appears to be either no reutilization or reutilization is at the polynucleotide level thereby escaping destruction by thymidine kinase. A possible method for studying this question is regional lymph node perfusion. Infusion of DNA pre- cursors into the lymph node would label only those cells in DNA synthesis within the lymph node and cells entering the node from other lymphoid organs would not be labeled, Celis leaving the lymph node can be monitored constantly by cannulating the efferent lymphatic duct. Effective prolongation of kidney allograft survival was obtained with pre- and post-grafting ECIB in some goats. However, for unknown reasons some kidneys were rejected normally. Effective immunosuppression by ECIB may depend upon the degree of histocompatibility between donor and recipient. Methods for determining the "closeness" of match between donors and recipients using the one way mixed leukocyte reaction and leukocyte typing will be applied. For ultimate clinical application it appears that ECIB, ECIL, or both, will have to be used in conjunction with drug immunosuppressive therapy. The effectiveness of ECIB and ECIL would be greatly enhanced if more lymphocytes could be mobilized from tissue and killed in transit through the blood. ECIB has been applied in patients ronic lymphocytic leukemia (CLL) with beneficial effects. i life? As Wh need treatment these studies will continue with the objective ining effect on longevity, morbidity, and duration of useful IB has no harmful effects in contrast to chemotherapeutic drugs that produce severe and sometimes fatal thrombopenia, granulocytopenia, anemia, and immunosuppression. An adequate evaluation will require at least 10-15 years and a continual flow of patients. (See Continuation Sheet) 1149221 RX-69