Whole body localization of intravenously injected lymphoblasts in normal rats.

Total body distribution of IUDR labeled thoracic duct, mesenteric and peripheral lymph node blasts was investigated, after i.v. injection into normal syngeneic rats. Donors of immunoblasts were stimulated with SRBC 1 week before transfer of cells. Lymphoblasts, irrespective of the source of origin, accumulated preferentially in small intestine, lungs, skin and muscles. There was an evident difference in the whole body distribution pattern of injected thoracic duct and lymph node blasts, what points to the different behaviour of normally circulating immunoblasts. Only minor differences in distribution kinetics and sites of accumulation were found between mesenteric and peripheral blast cells. We put forward a hypothesis that immunoblasts behave like effector cells and their preferential localization in small gut, lungs, and skin may be mediated by antigens "physiologically" present on the surgace of tissue with direct contact with the external environment.