High levels of T lymphocyte activation in Leishmania-HIV-1 co-infected individuals despite low HIV viral load

Abstract

Background: Concomitant infections may influence HIV progression by causing chronic activation leading to decline in T-cell function. In the Americas, visceral (AVL) and tegumentary leishmaniasis (ATL) have emerged as important opportunistic infections in HIV-AIDS patients and both of those diseases have been implicated as potentially important co-factors in disease progression. We investigated whether leishmaniasis increases lymphocyte activation in HIV-1 co-infected patients. This might contribute to impaired cellular immune function.Methods: To address this issue we analyzed CD4+T absolute counts and the proportion of CD8+T cells expressing CD38 in Leishmania/HIV co-infected patients that recovered after anti-leishmanial therapy.Results: We found that, despite clinical remission of leishmaniasis, AVL co-infected patients presented a more severe immunossupression as suggested by CD4+T cell counts under 200 cells/mm3, differing from ATL/HIV-AIDS cases that tends to show higher lymphocytes levels (over 350 cells/mm3). Furthermore, five out of nine, AVL/HIV-AIDS presented low CD4+T cell counts in spite of low or undetectable viral load. Expression of CD38 on CD8+T lymphocytes was significantly higher in AVL or ATL/HIV-AIDS cases compared to HIV/AIDS patients without leishmaniasis or healthy subjects.Conclusions: Leishmania infection can increase the degree of immune system activation in individuals concomitantly infected with HIV. In addition, AVL/HIV-AIDS patients can present low CD4+T cell counts and higher proportion of activated T lymphocytes even when HIV viral load is suppressed under HAART. This fact can cause a misinterpretation of these laboratorial markers in co-infected patients. © 2010 Santos-Oliveira et al; licensee BioMed Central Ltd.