The in vitro effect of a calf thymus extract (thymostimulin) on the immunologic parameters of patients with untreated Hodgkin's disease.

The in vitro effect of a calf thymus extract, thymostimulin (TP--1), on the E-rosette-forming capacity and on the PHA blastogenic response of peripheral blood lymphocytes was evaluated in 20 patients with untreated Hodgkin's disease. The mean percentage of lymphocytes forming E rosettes increased in patients from 44.2% to 57.5% (P less than 0.005). The mean PHA stimulation index rose with all three concentrations tested, but returned to the normal range only with the highest PHA concentration (60 mu/ml). An increase in the immune parameters was greatest in those patients who presented with decreased E-rosetting cells of total lymphocyte counts or whose disease was Stage III or IV or of mixed cellular histology.