IDENTIFICATION OF MIGRATORY GRAFT AND HOST-CELL POPULATIONS AFTER ALLOGENEIC RAT SMALL-BOWEL TRANSPLANTATION

This study used flow cytometry to identify graft cells in the recipien t peripheral blood and spleen and host cells infiltrating the graft me senteric lymph node and Peyer's patches after heterotopic rat small bo wel transplantation. Transplantation had little effect on the overall cell subset composition of these compartments and no changes appeared characteristic or indicative of developing rejection, suggesting that physiological control of cell migration remained unaltered. A small an d transient population of graft cells was detected in the peripheral b lood and spleen of the recipient which disappeared after 5 and 3 days respectively. Graft-derived cells in the peripheral blood comprised pr edominantly CD4(+) cells on day 1 with B cells predominating on day 5. Graft cells infiltrating the spleen were predominantly B cells. Host cells infiltrated the graft mesenteric lymph nodes and Peyer's patches to a lesser extent than previously reported using immunohistochemical analysis. For both tissues, infiltrating host-derived cells initially comprised mainly CD4(+) cells. On day 4 approximately equal proportio ns of CD4(+) and B cells were present in the mesenteric lymph node, wh ereas B cells were predominant in the host cell infiltrate of the graf t Peyer's patches. In summary, these findings indicate that the cell s ubset composition of recipient and graft lymphoid compartments does no t change after small bower transplantation, even in the presence of a substantial recipient cell infiltration. The reasons for the apparent discrepancies In the degree of host cell infiltration when assessed us ing immunohistochemical and localised release of soluble MHC class I i n graft tissues as a consequence of infiltrating host cell activation or localised cell destruction.