Increased levels of soluble interleukin-2 receptor in the serum of patients with human immunodeficiency virus infection

The serum levels of a soluble form of the interleukin-2 receptor (sIL-2R) were investigated in 92 patients with human immunodeficiency virus (HIV) infection, ranging from asymptomatic cases to full-blown AIDS. Increased values were found in 69.5% of cases. The overall mean was significantly higher (p less than 0.001) in HIV-infected patients (mean +/- SD = 709.3 +/- 369.4 U/ml) than in the seronegative risk group controls (383.9 +/- 140.5) and normal controls (256.4 +/- 114.5). No major differences were found among the patient groups (asymptomatic infection, persistent generalized lymphadenopathy, symptomatic infection, and full-blown AIDS). These data suggest that the measurement of serum sIL-2R levels may represent a useful biological tool for evaluating T-cell activation phenomena occurring in HIV infection. Since the soluble interleukin-2 receptor maintains the capacity of binding interleukin-2, the increased levels found in HIV infection may play a contributory role towards the in vitro and in vivo impairment of a number of interleukin-2-dependent functions described in this disease. On clinical grounds, the excess of sIL-2R could help to explain the lack of therapeutic effect and little immunological variations following the in vivo administration of interleukin-2.