Schistosomiasis mansoni is a
parasitic disease resulting in the deposition of ova predominantly in the liver and intestines. These ova secrete
antigens which induce host sensitization and evoke focal
granulomas. The
granulomas are intricate
delayed-hypersensitivity reactions governed by numerous cellular and humoral interactions. They displace or destroy normal tissue.
Vasoactive intestinal peptide (VIP) is one of several
neuropeptides which exert a broad range of
biologic actions that may include modulation of immune responses. In this study, VIP was sought within liver
granulomas isolated from Schistosoma mansoni-infected, CBA/J mice.
Granuloma extracts contained appreciable amounts of immunoreactive VIP as detected by radioimmunoassay. Immunoreactive VIP was shown, by each of two chromatographic methods, to elute as a single peak coinciding with that of synthetic VIP. In situ hybridization was performed with an
oligonucleotide probe complementary to a portion of the nucleotide sequence encoding VIP on
preproVIP mRNA (antisense probe). Radiolabeled VIP probe adhered exclusively to
granuloma eosinophils and to eosinophils within a
peritonitis induced in normal mice by
proteose peptone. Hybridization of radiolabeled VIP probe in the presence of unlabeled probe substantially attenuated binding. A sense probe failed to bind. These data suggest that the
granulomas contain authentic VIP and that eosinophils express the gene for this molecule.