Structure and biologic functions of human IgD. X. Enhancement of PHA responsiveness by anti-delta-activated...

Human peripheral lymphocytes with the capacity to be stimulated by anti-delta exhibited in PHA responsiveness when cultured with anti-delta 1 or 12 hr before PHA exposure over cells exposed to PHA alone. When these lymphocytes were preincubated with PHA 1 or 12 hr before anti-delta activation, no augmentation of the PHA response was seen. In addition, lymphocytes from donors with a high PHA response (low anti-delta activation) failed to show an enhancing effect on PHA responsiveness when pretreated with anti-delta. Moreover, anti-mu showed no synergistic effect on PHA responsiveness. This study is the first to indicate that anti-delta-activated cells enhance PHA responsiveness.