A NovelLeishmania infantumRecombinant Antigen Which Elicits Interleukin 10 Production by Peripheral Blood Mononuclear Cells of Patients with Visceral Leishmaniasis

Publisher Website
Google Scholar
Abstract
We report here the characterization of a novelLeishmania infantumprotein termed papLe22 (22-kDa potentially aggravating protein ofLeishmania). A positive clone from a cDNA library was identified by serum of a visceral leishmaniasis (VL) patient. Full-length cDNA obtained using rapid amplification of cDNA ends-PCR codes for a 22-kDa protein. InL. infantumpromastigotes an endogenous nuclear protein of 14-kDa electrophoretic mobility was found by using an antiserum prepared against the fusion protein glutathioneS-transferase–papLe22. Its expression was also shown inL. infantumamastigotes and inLeishmania majorandLeishmania guyanensispromastigotes. VL patients' sera showed anti-papLe22 immunoglobulin M (IgM) and IgG reactivities, indicating that a primary response against the leishmanial protein papLe22 accompanied acute VL manifestations. Specific IgG levels were correlated with patients' clinical status. The presence of IgG1, IgG2, and IgG3 subclasses suggested a mixed Th1- and Th2-type response; there was no correlation between subclass reactivity and the disease course. The recombinant papLe22 specifically activated interleukin-10 production by VL patients' peripheral blood mononuclear cells collected at diagnosis and after treatment-induced cure, indicating its contribution to VL pathogenesis and concomitant immunosuppression and its potential role in the reactivation of latent parasites. As a dominant immunogen, papLe22 might be used as a vaccine component, provided that the vaccination protocol directs the response toward the Th1 pattern.