Serum modulation of in vitro cellular immune reactivity to Epstein-Barr virus-associated antigen

The reactivity of peripheral blood leukocytes to Epstein-Barr virus-associated antigen was assessed employing two in vitro tests, leukocyte adherence inhibition (LAI) and leukocyte migration inhibition (LMI). In both tests, autologous serum from some normal subjects was shown to confer strong reactivity on weak or non-responder cells. Reactivity to purified protein derivative of tuberculin (PPD) assessed in parallel was shown to be unaffected by autologous serum. Employing the LAI system, variations in the effects of autologous serum samples collected on consecutive days was shown to be dependent on the reactivity of the leukocytes themselves, rather than changes in the activity or concentration of factors present in the serum.