Recognition of schistosome glycolipids by immunoglobulin E: Possible role in immunity

To investigate the role of antibody responses to (glyco)lipids in immunity to schistosome infection, lipids extracted from Schistosoma mansoni eggs an d adult worms were fractionated, and the antibody isotype profile reactive to the fractionated lipids in a well-characterized S. haematobium-infected population was investigated. In tests of 10 plasma samples it was found tha t immunoglobulin G (IgG) reactivity was highest to the fraction containing ceramidepolyhexosides, whereas IgE reactivity was most prominent to both ce rebroside- and ceramidepolyhexoside-containing fractions. The fraction cont aining ceramidepolyhexosides was then tested for reactivity with IgG subcla sses and IgE in plasma samples from 66 S. haematobium-infected patients. Co nsidering IgG4 and IgE, isotypes of particular interest in helminth infecti ons, we found that both isotypes recognized egg (glyco)proteins in more tha n 90% of the infected subjects. However, in the case of glycolipids, IgE re activity was much more prominent than IgG4 reactivity (found in 80 and 41% of the subjects, respectively). Furthermore, worm glycolipid-specific IgE p rior to treatment of the subjects with praziquantel was negatively correlat ed with egg counts at 2 years posttreatment, indicating that IgE directed t owards glycolipids could play an important role in resistance to reinfectio n.