PROTEIN-S AND HIV-INFECTION - THE ROLE OF ANTICARDIOLIPIN AND ANTI-PROTEIN-S ANTIBODIES

It has recently been reported that a large proportion of patients with HIV infection have low free protein S levels. In this study we show t hat protein S (PS) activity levels, as well as PS antigen (Ag), were s ignificantly lower in 35 HIV-1 infected patients than in the control p opulation (p < 0.001). When we divided HIV infected patients into thre e groups according to their CD4+ counts, we found that PS levels were significantly lower in patients with <100 CD4+ cells/ul. In order to i nvestigate the possible role of (auto)immune response in the pathogene sis of PS deficiency, the presence of anticardiolipin antibodies (aCL) and/or of the specific antibodies to protein S was evaluated. A high prevalence (77.1%) of aCL in both symptomatic and asymptomatic subject s was observed. The screening for specific anti-PS antibodies, perform ed by immunoblotting, showed an overall positivity of 28.6% in anti-HI V+ patients, with a higher prevalence in symptomatic than in asymptoma tic patients. Interestingly, the prevalence of the positivity for anti -PS antibodies was found to be higher in anti-HIV+ patients with PS le vels < 50%. Taken collectively, our findings suggest that at least one of the mechanisms through which PS levels are decreased in HIV infect ion, is due to the presence of specific autoantibodies.