Effect of several antiviral agents on human lymphocyte functions and marrow progenitor cell proliferation.

Toxicity to hematopoiesis and lymphocytic function are major considerations in the clinical applicability of antiviral agents. We have examined the toxicities of five antiviral agents showing activity against herpesviruses: vidarabine, acyclovir, (E)-5-(2-bromovinyl)-2'-deoxyuridine, trifluorothymidine, and (S)-9-(2,3-dihydroxypropyl)adenine. The drugs were tested in vitro for inhibition of herpes simplex virus type 1 and human cytomegalovirus replication, effects on marrow progenitor cell growth, effects on lymphocyte responses to mitogen and alloantigen stimulation, and effects on several lymphocyte cytotoxic responses. In general, lymphocyte proliferative responses were inhibited by the various drugs at lower concentrations than were cytotoxic activities. Acyclovir and (E)-5-(2-bromovinyl)-2'-deoxyuridine were the least toxic drugs tested, with antiviral indices exceeding 10,000. Vidarabine and trifluorothymidine were more toxic, with antiviral indices generally between 10 and 100. (S)-9-(2,3-dihydroxypropyl)-adenine was the most toxic, with several antiviral indices between 1 and 10.