In vitro effect of inosiplex on T lymphocytes. I. Influence on T cells with receptors for IgG (T gamma).

Inosiplex, a complex of inosine and 2-hydroxypropyldimethyl ammonium-4-(acetylamino)benzoate, 1:3 molar ratio, originally developed for antiviral use, is now under wider investigation because of its immunopotentiating properties. This compound can have some actions on T cells at various stages of differentiation, thus promoting an enhancement of their blastogenic responses to varied mitogenic agents (PHA, Con A, PWM, MLC, tetanus toxoid, and viral antigens). Our studies demonstrated that under the influence of inosiplex human peripheral blood T lymphocytes bearing Fc IgG receptors have an augmented receptor avidity for SRBC which result in an increased E active rosette formation, and that T cells preincubated with the drug at the appropriate concentrations express more Fc IgG receptors. Even though T gamma cells exert "in vitro" immunoregulatory properties, the increase in percentage of T gamma lymphocytes do not correlate with a potentiation of the Con A-induced suppressor activity of T cells. Moreover, the lymphocytes treated with the substance in the absence of Con A exert helper functions, increasing the mitogenic responses of the second culture PHA--treated lymphocytes. These data appear to suggest a pro-proliferative inosiplex-induced effect which could mask a concomitant suppressor cell induction.