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

Specific serum antibodies, peripheral blood T-cell subsets, cellular respon se in vitro to soluble Leishmania antigens, phenotype of stimulated cells, and serum levels of tumour necrosis factor (TNF)-alpha and transforming gro wth factor (TGF)-beta 1 were studied in Spain in 17 patients co-infected wi th HIV and Leishmania infantum who had been previously treated with pentava lent antimony. Both humoral and cellular responses to Leishmania sp. appear ed diminished, 8 out of 17 patients were positive by indirect immunofluores cence, and immunoblotting detected heterogeneous antibody-binding pattern i n 11 out of 13 subjects. A blastogenesis test was positive in 4 cases; 2 of them presented proliferation of CD4(+) cells while CD8(+) cells proliferat ed 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-bet a 1 were significantly lower in the co-infected patients. The inability of antibody response to control the parasite and the absence of specific T-cel l immunity to Leishmania sp. would explain the high frequency of relapses r eported in these patients. The decreased levels of TGF-beta 1 could have an important role in the interaction between the 2 pathogens.