Schistosoma mansoni antigens alter the cytokine response in vitro during cutaneous leishmaniasis

Schistosoma mansoni infection or associated products are able to down-modulate the type 1 CD4+ T cell inflammatory response characteristic of autoimmune diseases. In this study, we evaluated how S. mansoni antigens altered the immune response that was induced by the soluble Leishmania antigen (SLA) from cutaneous leishmaniasis (CL) patients. Cytokines were measured from the supernatants of peripheral blood mononuclear cell cultures stimulated with SLA. This was performed using the sandwich enzyme linked immunosorbent assay technique in the presence or absence of S. mansoni recombinant antigens Sm29, SmTSP-2 and PIII. The addition of S. mansoni antigens to the cultures resulted in the reduction of interferon gamma (IFN-γ) levels in 37-50 percent of patients. Although to a lesser extent, the antigens were also able to decrease the production of tumour necrosis factor-alpha (TNF-α). We compared patients that either had or did not have reduction in IFN-γ and TNF-α production in cultures stimulated with SLA in the presence of S. mansoni antigens. We found that there was no significant difference in the levels of interleukin (IL)-10 and IL-5 in response to S. mansoni antigens between the groups. The antigens used in this study down-modulated the in vitro proinflammatory response induced by SLA in a group of CL patients through a currently undefined mechanism.

Comparative effect of ion calcium and magnesium in the activation and infection of the murine macrophage by Leishmania major

Amastigotes of Leishmania major have a great ability to evade destruction in host cells. This study investigated the activation in resident, inflammatory macrophages and J774 cells in vitro treated with lipopolysaccharide (LPS), soluble Leishmania antigen (SLA), calcium ionophore (CaI) and magnesium (Mg2+) alone or combined. An increase in nitric oxide (NO) production was observed in J774 or inflammatory macrophages treated with LPS alone or in combination with SLA and CaI. The same treatments did not affect the NO release by resident macrophages. There was no interference in uptake of L. major but CaI decreased intracellular proliferation of the parasite. This study demonstrated the importance of CaI in decreasing L. major proliferation inside murine macrophages while Mg2+ seemed to increase parasite proliferation. These finding may help to understand the events involved in host cells' clearance of this pathogen..

Effect of Leishmania donovani antigens on superoxide anion generation by mice polymorph in vitro.

The present study was planned to study the effect of priming of BALB/c mice peritoneal polymorphs (PMNLs) by viable, heat killed and formaline fixed promastigotes of L. donovani and soluble extract of proteins of L. donovani promastigotes on their capacity to produce toxic oxygen radicals (TOR). TOR production was measured by superoxide dismutase (SOD), inhibitable cytochrome C reduction and nitroblue tetrazolium reduction tests. No significant stimulation or inhibition in SOD inhibitable cytochrome C reduction and nitroblue tetrazolium reduction was seen when PMNLs were primed by soluble leishmanial protein, and formalin fixed and denatured promastigotes for both 60 and 90 min. Priming of BALB/c mice peritoneal polymorphs with live promastigotes of L. donovani for more than 60 min produced approximately 30 per cent inhibition in superoxide generation as measured by both the tests (P < 0.05). The inhibition in superoxide generation by polymorphs may be one of the important escape mechanisms in the causation of the visceral leishmaniasis.