Effects of IL‐2 therapy in asymptomatic HIV‐infected individuals on proliferative responses to mitogens, recall antigens and HIV‐related antigens

The effects of IL‐2 therapy on lymphoproliferative responses to mitogens, recall antigens and HIV epitopes were studied in asymptomatic HIV‐infected patients enrolled in a phase II study of intermittent continuous intravenous (CIV) IL‐2 and subcutaneous infusions of polyethylene glycol‐modified (PEG) IL‐2. Sixteen consecutive patients randomized to receive CIV IL‐2 (n = 5), PEG IL‐2 (n = 7) or anti‐viral therapy alone (n = 4) were studied. All patients were vaccinated with tetanus toxoid (TT) before receiving therapy. Proliferative responses to phytohaemagglutinin (PHA), soluble anti‐CD3, TT, streptokinase/streptodornase (SK/SD) and 11 previously described HIV‐specific T‐helper epitopes from gag and env were studied at weeks 0, 16, 30 and 48. Median CD4+ lymphocyte increases of 272 and 255 CD4+ cells/μl were observed in the CIV IL‐2 and PEG IL‐2 groups at week 48, while decreasing by 104 cells/μl in the anti‐retroviral therapy alone group. At each time point proliferative responses to PHA, anti‐CD3, TT and SK/SD were not different between treatment arms. Similarly, no differences in responses to HIV epitopes were found between the groups and no new responses to HIV epitopes were detected. IL‐2 therapy results in a significant increase in peripheral blood CD4+ lymphocyte count, but this increase is not associated with quantifiable improvements in lymphoproliferative responses to mitogens, recall or HIV antigens.