Human immune response to sand fly salivary gland antigens: A useful epidemiological marker?

Antibody (IgG) responses to salivary gland homogenate and to a recombinant salivary protein from the sand fly Lutzomyia longipalpis were investigated using sera from children living in an endemic area of visceral leishmaniasi s in Brazil. We classified children into four groups according to their res ponses to Leishmania antigen: (Group I) positive serology and positive dela yed type hypersensitivity (DTH), (Group II) positive serology and negative DTH, (Croup III) negative serology and positive DTH, and (Group IV) negativ e serology and negative DTH. A highly significant correlation was found bet ween anti-salivary gland IgG levels and DTH responses. An L. longipalpis sa livary recombinant protein used as an antigen in an enzyme-linked immune so rbent assay (ELISA) gave a significant but different result. A positive cor relation was found between anti-leishmania IgG and anti-recombinant protein IgG titers. The results indicate that sand fly salivary proteins may be of relevance to the study the epidemiology of leishmaniasis.