Interleukin-2 therapy for HIV* individuals
Interteukin 2 (IL-2), a cytokine normally produced during Immune responses, promotes the proliferation and differentiation of lymphocytes. Administered in high doses to HIV+ individuals, IL-2 causes extreme toxicity and actually increases plasma HIV levels. Low doses of IL-2 are nontoxic, but have yet to be tested for safety regarding viral replication, or the potential to augment immune reactivity in asymptomatic HIV infected individuals. A phase I study was conducted. 14 HIV+ individuals with 200-500 CD4+ T cells/mm9 received IL-2 for 6 months in daily, subcutaneous doses ranging from 62,500 to 250,000 IU (4-16 tig)/nf. All individuals also received nucleoside analog antiretroviral therapy. Clinical. Virologie and immunologie parameters were monitored. The maximum tolerated dose (MTD) ranged from 187,500 IU (12.5 ng)/m2/d to 250,000 IU (16.7 ng)/m2/d, and was determined by systemic symptoms of fatigue, malaise, myalgia and low grade fever (<39 °C). IL-2 was detectable in low concentrations in the plasma of most HIV+ individuals before therapy. In eight individuals who received the MTD, peak plasma IL-2 levels were near receptor saturating. At the MTD, IL-2 augmented cell mediated immunity without significant increases of plasma HIV. Asymptomatic HIV+ individuals can self-administer IL-2 safely without toxicity for as long as 6 months. Expanded clinical trials of low dose IL-2 are warranted.