Prediction of Immunosuppressive Potency of Antilymphocyte Serum by in Vitro Testing

Abstract

Seventeen batches of rabbit anti-mouse lymphocyte serum (RAMLS) and normal rabbit serum were tested for ability to prolong allografts of CBA skin on BALB/c mice, and the leukoagglutinating, cytotoxic and both direct and indirect macrophage-cytophilic antibody titers of these sera were determined. Simple linear regressions of survival times of individual grafts on titers of each measurement disclosed statistically significant correlation in each case. Multiple linear regression analysis was used to establish the relative value of the four methods of assay in predicting allograft survival. The most efficient predictor was a mathematical model that included only the two cytophilic antibody titers. The predictive value was not improved by including agglutinating and cytotoxic antibody titers. These results established a close association of cytophilic activity with the immunosuppressive potency of RAMLS, and suggested that the roles of cytotoxicity and leukoagglutination per se are minor.