Subcutaneous interleukin-2 in combination with anti-retroviral therapy for treatment of HIV-1-infected subjects.

A total of 11 HIV-1 positive patients, with CD4+ cell counts between 200 and 500/microl, who were in stable anti-retroviral therapy, were treated with subcutaneous recombinant human IL-2 thrice weekly administered on an out-patient basis in a dose-escalating manner. Subcutaneous IL-2 was well tolerated and associated with only mild to moderate constitutional symptoms and local inflammation at the injection site. CD4+ cell count increased from 404 +/- 48/microl at baseline to 639 +/- 88/microl at week 6, with proportionate increases in naive cells and memory cells. Increased doses of IL-2 were then needed to sustain the number of CD4+ cells. After discontinuation of IL-2 treatment, CD4+ cell count returned to baseline levels. IL-2 induced a reduction in the percentage of CD8+ CD38+ and CD8+ HLA-DR+ cells, an increase in the fraction of CD8+ CD25+ and CD8+ CD122+, and an elevation in the number of NK-cells. IL-2 did not induce any clinically significant change in plasma HIV-RNA. In conclusion, IL-2 can safely be administered subcutaneously on an out-patient basis to HIV-infected individuals with CD4+ cell counts from 200/microl to 500/microl and with some improvement in immunological abnormalities. Continuous therapy, however, seems to result in the development of tachyphylaxia.