Immune enhancement in mice by ara-A.

Ara-A in single, apparently nontoxic doses stimulates murine immune responses to several well-defined antigens. Both humoral and cell-mediated responses are enhanced by ara-A, but not all mouse strains respond equally well. In certain mouse strains, ara-A also promotes increased (or decreased) survival during experimental infection with Cryptococcus neoformans, suggesting that clinically significant effects on host resistance may result from the use of ara-A as an antiviral therapeutic agent. The biochemical mechanisms of action of the aranucleosides suggest that the immunostimulation produced by ara-A depends on suppressor cell toxicity.