Immune restoration by combination of a cytostatic drug (hydroxyurea) and anti-HIV drugs (didanosine and indinavir)

Cell activation is essential for HIV infection. CD4⁺ T lymphocyte activation allows virus replication and CD8⁺ T lymphocyte activation may contribute to pathogenesis. We combined hydroxyurea, a cytostatic drug that inhibits cell activation and proliferation, with two drugs that inhibit HIV (didanosine and indinavir), to block the 'cell activation-virus production- pathogenesis' cycle. HIV was strongly suppressed in treated patients, and the average CD4 count increased to 224/mm⁺. Compared with a matched group of patients who had declined antiretroviral treatment, treated patients had a significantly lower proportion of activated CD8⁺ T lymphocytes and a significantly higher number of naive CD8⁺ and CD4⁺ T lymphocytes. The proliferative responses to allogeneic and influenza virus antigens were increased in treated patients, and a defect in CD3-ζ expression, the signaling chain of the T cell receptor complex, was reversed. The use of a cytostatic drug was not detrimental to the immune system; on the contrary, the combination of antiviral and cytostatic treatment improved all of the immune parameters tested.