ANALYSIS OF ALLOGENIC LYMPHOCYTES IN RAT THYMUS FOLLOWING SUBLETHAL IRRADIATION

The effects of allogeneic lymphocytes on the rat thymus following subl ethal irradiation were investigated using immunofluorescence. The reco very of thymus weight following irradiation was delayed in rats 6 days after receiving lymphocytes compared to controls. Allogeneic cells fo rming colonies were detected by immunofluorescence in both the cortex and medulla of the host thymus, most frequently on day 15 when an appr opriate number (3x10(6)) was injected. The allogeneic cells detected i n the host thymus, presumably T lymphocytes, appeared to disturb thymi c reconstitution following irradiation. However, double-immunofluoresc ence staining revealed that allogeneic cells did not affect the thymic stromal microenvironment. Allogeneic cells may have subsequently affe cted thymic tissue via cytokines. It is important to investigate not o nly the character of allogeneic cells in the host thymus but also the interactions of donor allogeneic cells, host immature lymphocytes and thymic epithelial cells because of the possibility that these allogene ic cells in the host thymus could prevent the rejection of allogeneic transplants.