Human immune responses to Schistosoma mansoni vaccine candidate antigens

To determine the naturally occurring immunological responses to the Schisto soma mansoni antigens paramyosin, IrV-5, Sm-23 (MAP-3), and triose phosphat e isomerase (MAP-4), a total of 119 subjects from an area of endemicity for schistosomiasis, including "resistant" subjects (n = 17) were evaluated. S pecific immunoglobulin G1 (IgG1), IgG2, IgG3, IgG4, and IgA levels for each of the antigens and the cytokine profile in culture supernatants from anti gen-stimulated peripheral blood mononuclear cells (PBMC) were determined. A lthough all the subjects had a high degree of contaminated water exposure, their infection levels were variable (0 to 1,128 eggs/g of stool). There we re direct correlations between infection levels and levels of SWAP- and par amyosin-specific IgG1 and IgG4 (P < 0.05). However, an inverse correlation between infection levels and specific IgG2 to IrV-5 (P < 0.01) was observed . The evaluation of the cytokine profile (interleukin 5 [IL-5], IL-10, gamm a interferon [IFN-gamma], and tumor necrosis factor alpha) in response to t hese antigens showed inverse correlations between the degree of infection a nd IFN-gamma levels in PBMC supernatants stimulated with paramyosin (P < 0. 05) and IrV-5 (P < 0.01). Additionally, inverse correlations between the de gree of infection and IL-5 levels in MAP-3- and MAP-4-stimulated PBMC super natants (P < 0.01) were found. Logistic regression analysis was performed t o adjust the results of cytokine profile by age. IL-5 production in MAP-3-s timulated PBMC supernatants was associated with lower infection levels (odd s ratio = 11.2 [95% confidence interval, 2.7 to 45.8]).