Immunohistochemical localization and differentiation of phosphocholine-containing antigens of the porcine, parasitic nematode, Ascaris suum.

The glycolipids of Ascaris suum represent either neutral, zwitterionic or acidic structures. The acidic fraction comprises a sulphatide and an unusual phosphoinositolglycosphingolipid (Lochnit et al. 1998b). The sulphatide was previously localized to the hypodermis, contractile zone of somatic muscle cells and the external musculature of the female uterus, whereas the presence of the phosphoinositolglycosphingolipid species was restricted to the intestine. The neutral and zwitterionic components belong to the arthro-carbohydrate series, which are substituted in their zwitterionic structures by phosphocholine (PC) and in one glycolipid by an additional phosphoethanolamine residue. In previous immunohistochemical localization studies, however, the chemical nature of the PC-substituted biomolecules has not been investigated in detail. Here, we report on the immunohistochemical localization and differentiation of phosphocholine-containing structures into lipid- and protein-bound species in adult A. suum. The patterns of immunostaining, obtained with a PC-specific monoclonal antibody and anti-zwitterionic glycolipid hyperimmune serum in the female worm, indicated a parallel organ distribution for glycolipid- and protein-bound PC-epitopes. Immunoreactivity was localized to specific tissues of the body wall, intestine and reproductive tract. This is the first report of surface-located PC-epitopes for ascarids. The patterns of immunolabelling obtained with antibodies directed against the unsubstituted arthro-carbohydrate series backbone suggested that the glycolipid-bound epitope was restricted to the hypodermis, whilst the protein-bound antigenic determinant resembled that for PC.

Structural analysis and immunohistochemical localization of two acidic glycosphingolipids from the porcine, parasitic nematode, Ascaris suum.

The acidic glycolipid fraction (AF) of the porcine, parasitic nematode, Ascaris suum , consisted of two subfractions. The major component AF II reacted with orcinol-sulfuric acid and molybdate, while the minor component AF I gave a positive reaction with azure-A, a cationic dye specific for sulfatides. Sugar constituent analysis, methanolysis, methylation analysis, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, liquid secondary-ion mass spectrometry, and gas-liquid chromatography/mass spectrometry specified AF II to be an unusual phosphoinositolglycosphingolipid (Galalpha1-Ins-P-1ceramide) and the minor component AF I to be a 3-sulfogalactosylcerebroside (HSO3-3Galss1-1ceramide). The ceramide moiety of both components consisted of lignoceric (C24:0) and cerebronic (C24h:0) acids and mainly C17 iso-branched sphingosine. Immunohistochemical localization studies of the glycolipid-bound antigenic determinants with a polyclonal antiserum against AF II and an anti-sulfatide monoclonal antibody against AF I revealed the presence of the AF II-epitope in the intestine, whereas the AF I-epitope was found in the hypodermis, contractile zone of somatic muscle cells and the external musculature of the uterus. To our knowledge, this is the first report of the presence of a sulfatide in an invertebrate.