Phenotypic definition of primed T cells in human renal allografts: use of the CD45R marker

: Immunohistological studies indicate that T cells and macrophages are the major components of human kidney allograft infiltrates. Recent work has demonstrated a division of T lymphocytes into 2 subpopulations with distinct functions on the basis of their expression of the CD45R antigen (CD45R+ "naive" and CD45R- "memory" T cells). This study analyzes CD45R expression on circulating T cells and T cells infiltrating renal allografts in patients undergoing rejection and/or cyclosporine nephrotoxicity. The percentage of circulating T cells that expressed CD45R in patients with rejecting (63 +/- 4) or stable grafts (66 +/- 3) was not different from values obtained for normal donors (62 +/- 3). In contrast, the percentage of T cells expressing CD45R infiltrating rejecting grafts was 21 +/- 2 and was not affected by the stage of rejection; in patients with CsA toxicity the value was 22 +/- 6. The reduced proportion of T cells that expressed CD45R in the allograft may reflect a change in status from the naive state due to alloantigenic stimulation (which can be demonstrated in vitro) and/or a propensity of memory T cells to enter or be retained in an allograft.