Migration patterns of lymphocytes from recipients of organ allografts. I. The unmodified host.

Abstract

We have investigated in the rat, serial dynamics and homing patterns of different lymphocyte populations from unmodified recipients of heterotopic cardiac allografts and have compared these kinetics to those of lymphocytes from isografted or nongrafted control animals. Sensitized lymphocytes were labeled in vivo and in vitro. Groups of allografted rats were inoculated in vivo with [6-3H]thymidine serially following transplantation. Alternatively, lymphocytes were isolated from all lymphoid compartments of recipient animals at intervals following grafting and labeled with 51Cr. Spleen cell suspensions were further fractionated into nylon-wool adherent (SIg+) and nonadherent (T) populations, which were then differentially labeled with [2-14C]thymidine and [6-3H]thymidine, respectively. All cell groups were then transferred into normal syngeneic animals, and migration patterns into all lymphoid and nonlymphoid organs were assessed 24 hr later. In vivo labeling of sensitized lymphocytes showed a significant increase in radioactivity in recipient lymph nodes, spleen, and grafted heart during the period of rejection at 8 days, compared to isograft or normal controls. Dynamics of in vivo labeled lymphocytes from allografted rats differed markedly from controls; total radioactivity of blood and all lymphoid organs of test rats rose progressively (P < 0.001) until the time of rejection, with reciprocal decrease of accumulated radioactivity in nonlymphoid tissues. Distribution and kinetics of all lymphoid cell groups with the exception of those from bone marrow were comparable following transfer into test animals, invariably increasing in lymphoid tissues during the period of rejection, and decreasing in reciprocal relationship in nonlymphoid tissues. Results from double-labeled nylon-wool nonadherent and adherent cells showed that the T to B cell ratio increased steadily in lymph nodes, Peyer's patches, and spleens of test animals between 2 and 8 days, and declined in blood and small intestine.