Suppressor cell activity in human renal allograft recipients.

Eighty-nine kidney allograft recipients with one or more graft rejection episodes were monitored for suppressor cell activity in the peripheral blood at two day intervals. The impact of rejection and immunosuppressive therapy (ALG) on the one hand and the recovery of suppressor activity on the other hand during long-term graft survival could be demonstrated. The suppressor activity of peripheral lymphocytes after amplification in vitro by Concanavalin A was measured on PHA stimulated cultures. It is reduced after operation trauma and during rejection episodes when tested in PHA stimulated cultures. This loss of suppressor activity is even more marked when suppressor cells are added to allogeneic mixed lymphocyte reactions. Depletion of adherent cells reduces this suppressor activity, indicating that two different populations of mononuclear cells are responsible for this in vitro effect. Immunosuppressive therapy and additional ALG treatment abolishes suppressor activity in most cases. Highest suppressor activity was monitored in seven patients with excellent long term graft survival after ALG therapy.