Atypical cutaneous leishmaniasis cases display elevated antigen-induced interleukin-10

In humans, Leishmania chagasi parasites can produce subclinical infections, atypical cutaneous leishmaniasis (ACL) and visceral leshmaniasis that is potentially fatal if not treated in a timely fashion. L. chagasi parasites that cause both ACL and visceral disease appear to be genetically similar, which suggests that host factors such as the immune response play an important role in controlling infection. We evaluated the immunologic response in ACL using peripheral blood mononuclear cells (PBMCs) of 37 subjects divided into three groups: (i) active ACL cases, (ii) asymptomatic cases and (iii) persons with no history of Leishmania infection. The supernatants of stimulated PBMCs were analysed for production of IL-10, IFN-gamma and IL-2. Robust production of IL-10 in response to Leishmania stimulation was observed in active ACL cases, compared to low levels in asymptomatic cases and negative controls. Serum IgE levels, measured by ELISA, were not significantly different among the three groups. In addition, ACL cases displayed depressed levels of all cytokines in response to mitogen. Thus, this first characterization of the immune response in ACL suggests a role for IL-10 as well as partial immunosuppression.