Interleukin 2 receptor expression on peripheral blood lymphocytes in association with renal allograft rejection

Periodic assay of IL-2 receptor expression on the surfaces of peripheral blood lymphocytes might provide information predictive of in vivo immunologic events. This study compares two methods of determining IL-2 receptor expression after renal transplantation in cynomolgus monkeys. The first utilized single color staining of peripheral blood mononuclear cells with mouse anti-human IL-2 receptor monoclonal antibody followed by a fluorescein-labeled goat anti-mouse IgG antibody. Epics C cell sorter windows were set to count cells of the size and granularity of normal lymphocytes. The second utilized two-color staining with fluorescein-labeled anti-IL-2 receptor antibody, combined with phycoerythrin-labeled anti-CD4 antibody or with phycoerythrin-labeled anti-CD8 antibody. Two-color staining allowed the sorter windows to be enlarged to count all mononuclear cells, regardless of size or granularity, without introducing the contaminating effects of monocytes. Data obtained from single-color staining showed no consistent or significant expression of the IL-2 receptor on peripheral lymphocytes in association with the rejection process. Data obtained from two-color staining revealed an increase of IL-2 receptor expression on peripheral T cells of at least 10% from the postoperative baseline, which preceded the creatinine rise from allograft rejection in 13 of 13 animals. Increases in IL-2 receptor expression on T cells were not specific to rejection, however. Some animals in which treatment produced a delay of rejection showed a transient rise in IL-2 receptor expression around post-transplant day 5, which was not followed by a rise in creatinine. The two-color staining technique described provides a sensitive means of detecting IL-2 receptor expression in vivo and documents the association of increases in IL-2 receptor expression on T cells with rejection.