High levels of CD4⁺ CTLA-4⁺ Treg cells and CCR5 density in HIV-1-infected patients with visceral leishmaniasis.

Visceral leishmaniasis (VL) in HIV-1-infected patients has been associated with poor immunological recovery and frequent disease relapses. The aim of this study was to analyse the role of T cell populations, Treg cells and CCR5 density in patients with VL compared to HIV-1-infected patients without leishmaniasis. A cross-sectional study of nine Leishmania–HIV-1-coinfected (LH) patients with VL receiving suppressive cART for at least 1 year were compared to 16 HIV-1-infected patients with non-immunological response (NIR, CD4 count below 250 cells/mm3) and 26 HIV-1-infected patients with immunological response (IR, CD4 count above 500 cells/mm3) without leishmaniasis. LH patients had a deep depletion of naive T cells (p = 0.002), despite similar levels of effector T cells compared to NIR patients. CD4 Treg cells were similar compared to NIR patients, but higher compared to IR patients (p < 0.001). Interestingly, CD4 Treg CTLA-4+ cells were higher in LH patients compared to either NIR or IR patients (p = 0.022 and p < 0.001, respectively), and the CD4 Treg/TEM ratio was similar to NIR patients, but higher compared to IR patients (p = 0.017). CCR5+ T cell levels were higher compared to IR patients (p < 0.001), while CCR5 density on T cells were higher compared to both NIR and IR patients (p < 0.005 in both cases). Higher levels of CD4+ CTLA-4+ Treg cells and CCR5 density on CD8+ T cells are strongly associated with VL in HIV-1-infected patients. Also, these patients have a poor immunological profile that might explain the persistence and relapse of the pathogen.