Effects of subcutaneous interleukin-2 therapy on phenotype and function of peripheral blood mononuclear cells in human immunodeficiency virus infected patients

In the context of clinical therapy with recombinant human interleukin-2 (IL-2), we monitored immunological alteration in 10 human immunodeficiency virus type-1 (HIV-1)-infected individuals, on stable antiretroviral therapy, who had a CD4⁺ cell count between 200 and 500 cells/mm³. Subcutaneous IL-2 was prescribed thrice weekly (at a dose of 3 x 10⁶ IU) for 24 weeks and the patients were followed-up for 32 weeks. IL-2 treatment induced an increase in the CD4⁺ percentage (P < 0.001) and CD4⁺ cell count (P < 0.009). Furthermore, natural killer (NK) cell activity was increased (P < 0.001) at week 8 of treatment, whereas lymphokine-activated killer (LAK) cell activity showed a transient, nonsignificant increase at week 8 and was reduced (P < 0.001) at 32 weeks. However, the cytotoxic T-lymphocyte (CTL) activity decreased against HIV antigens, and the proliferative response to Candida, IL-2 and phytohaemagglutinin (PHA) declined during the first 8 weeks (P < 0.05) and returned to baseline levels after 32 weeks. The HIV RNA level did not change during IL-2 therapy; however, after 8 weeks of follow-up a significant increase (P < 0.001) in viral load was observed. In conclusion, continuous IL-2 treatment to HIV-infected individuals enhanced the CD4 count, but the in vitro lymphocyte function was impaired and an increase in viral replication occurred after treatment.