Changes in blood lymphocyte populations in experimental bowel allograft rejection

The aim of this study is to measure percentages of lymphocyte populations and IL-2R cellular expression in peripheral blood during the rejection of a small bowel allograft (SBA) in the rat. Thirty rats were allotted to three groups: A, control, no transplantation (Tx); B, rats receiving an orthotopic SBA; C, similar SBA but with thymostimulin (TP-1) administered before Tx, aimed at increasing the intensity of and accelerating rejection. The percentages of CD19, CD5, CD4 and CD8 cells and of IL-2R were determined when rejection was present. Rejection appeared in rats in group B between days 11 and 26 post-Tx and in group C between days 6 and 7 post-Tx (P < 0.001). In both B and C groups, CD5 and CD4 cells decreased (P < 0.005) and CD8 cells increased (P < 0.001). A correlation between CD8 and IL-2R content was found (P < 0.05). In group C, earliness of rejection correlated with the percentage of CD8 cells (P < 0.05) and the intensity of rejection with numbers of CD8 and CD19 cells (P < 0.05).