Elevated levels of soluble non-classical major histocompatibility class I molecule human leucocyte antigen (HLA)-G in the blood of HIV-infected patients with or without visceral leishmaniasis

The non-classical class I major histocompatibility complex molecules human leucocyte antigen (HLA)-G have been shown to play a role in HIV persistence, but no data are available on the expression of the soluble forms HLA-G5 and sHLA-G1 in HIV-infected patients with and without opportunistic infections. The soluble HLA-G isoform was measured with an enzyme-linked immunosorbent assay (ELISA) method in plasma from 94 subjects: 31 HIV-1-seropositive, 17 with visceral leishmaniasis (VL), seven with both VL and HIV-1 infection and 39 healthy HIV-seronegative subjects. Between groups, the frequency of sHLA-G positivity was statistically different: 81% of HIV-infected patients were positive, as were 57% of HIV-Leishmania infantum co-infected patients, 35% of HIV-seronegative patients with VL and 3% of healthy controls. Levels of the soluble forms of the immunomodulatory molecules HLA-G are elevated during HIV infection. In HIV-Leishmania co-infected patients, sHLA-G secretion could contribute to the tolerogenic environment and to Leishmania immune evasion.