Differentiation between irreversible and reversible rejection in renal transplant patients by monitoring of phytohemagglutinin-induced cytotoxicity.

Phytohemagglutinin (PHA)-induced cytotoxicity against adherent HeLa cells, a reproducible test for primary T cell cytotoxicity, was used in the followup of 34 renal transplant recipients and related to the outcome. During the 1st week, two uncomplicated cases showed a decrease in cytotoxicity of more than 20% and it remained low. One patient with a cytomegalovirus (CMV) infection showed a marked increase in cytotoxicity (37%) and it remained high. In 31 patients with a rejection episode, a change of -20 to +20% was observed. During the 2nd week, all 10 patients who developed an irreversible rejection showed an increase of more than 20% (mean, 29 +/- 8%), in contrast to only 2 of 21 patients with a reversible rejection (mean, -1 +/- 15%, P less than 0.001). There were no differences between these two groups in lymphocyte and T lymphocyte counts, or in prednisone or azathioprine dose or blood urea nitrogen levels. These results indicate that regular assessment of PHA-induced cytotoxicity may be useful in the followup of renal transplant patients.