HIV--Leishmania infantum co-infection: humoral and cellular immune responses to the parasite after chemotherapy.

Specific serum antibodies, peripheral blood T-cell subsets, cellular response in vitro to soluble Leishmania antigens, phenotype of stimulated cells, and serum levels of tumour necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta 1 were studied in Spain in 17 patients co-infected with HIV and Leishmania infantum who had been previously treated with pentavalent antimony. Both humoral and cellular responses to Leishmania sp. appeared diminished, 8 out of 17 patients were positive by indirect immunofluorescence, and immunoblotting detected heterogeneous antibody-binding pattern in 11 out of 13 subjects. A blastogenesis test was positive in 4 cases; 2 of them presented proliferation of CD4+ cells while CD8+ cells proliferated in the other 2 patients. Serum levels of TNF-alpha were similar to those observed in patients infected with HIV only, while serum levels of TGF-beta 1 were significantly lower in the co-infected patients. The inability of antibody response to control the parasite and the absence of specific T-cell immunity to Leishmania sp. would explain the high frequency of relapses reported in these patients. The decreased levels of TGF-beta 1 could have an important role in the interaction between the 2 pathogens.