Immunological study of unresponsive state in rat hepatic transplant model. 1. Phenotypic and functional analyses of infiltrating cells.

Abstract

In order to elucidate the immunological characteristics of rat liver transplantation, graft-infiltrating cells (GIC) isolated from rat hepatic allografts were analyzed phenotypically and functionally. GIC from long-surviving recipients (Brown Norway livers into Lewis hosts) and acutely rejecting recipients (DA livers into Lewis hosts) were compared. The relative proportions of all T cells and activated T cells determined by flow cytometry were significantly higher in acutely rejecting Lewis recipients than in long-surviving recipients on day 6 after grafting. Phenotypic kinesis of GIC on days 6, 14, and 45 after transplantation from long-surviving Lewis hosts was analyzed. Each proportion of all T cells, OX8-positive cells (cytotoxic T and natural killer cells), and OX39-positive cells (IL-2 receptor), was greatest on day 6 and decreased by day 45. Cytotoxic activity of GIC toward donor lymphocytes on day 6 was greater in acutely rejecting versus long-surviving recipients. These results demonstrate that an immunosuppressive mechanism is already present on day 6 posttransplantation, and that infiltration or activation of cytotoxic T cells is inhibited in the long-surviving rat hepatic allografts.