Evidence for a role of T-helper type 2 cytokines in the acquisition of human immunodeficiency virus syncytium-inducing phenotype

Background The objective of the present study was to investigate the relati onship between the serum cytokine pattern of T-helper (Th) response and the acquisition of syncytium-inducing (SI) human immunodeficiency virus type 1 (HIV-1) variants in HIV-1-seropositive patients treated with antiretrovira l drugs. Methods Serum cytokines of Th1/Th2 responses were analysed in a case-contro l study of 20 individuals selected from a cohort of HIV-1-infected patients without SI variants at entry, who developed or did nor develop SI virus du ring a prospective follow-up. A group of 10 patients with SI variants at st udy entry was also evaluated. Serum concentration of interferon (IFN) gamma , interleukin (IL) 2, IL-4 and LL-10 was evaluated by mean of a commercial enzyme immunoassay. Results Despite close matching for immunological (CD4(+) cell count) and vi rological (p24 antigen, serum HIV viraemia) parameters, SI-converting patie nts showed at baseline significantly lower serum levels of IL-2 and higher concentrations of IL-4 than those who remained persistently negative for SI variants. Shortly after the phenotype conversion, SI-converting patients w ere characterized by significantly high serum concentration of IL-4 and by low levels of IFN-gamma (Th2-like pattern). Patients with SI phenotype at s tudy entry featured lower mean levels of both IL-4 and IL-10, but mean IFN- gamma and IL-2 values were higher, although the clinical and immunological baseline was also poorer and no statistical analysis could be applied. Conclusion Serum cytokine pattern of Th1/Th2 response differs between patie nts with NSI and SI phenotype. Our data strongly suggest that the Th2 cytok ine pattern could be associated with the acquisition of the SI HIV-1 phenot ype.