Lewis(x)-containing oligosaccharide attenuates schistosome egg antigen-induced immune depression in human schistosomiasis

The proliferative and interleukin (IL)-10 responses to Lacto-n-fucopentaose III (LNFPIII) that contains Lewis(x)(Le(x))-trisaccharide was assessed in PBMC from humans infected with Schistosoma mansoni. All patient groups with low, medium, and high egg counts in their feces responded to polyvalent LN FPIII-HSA (where HSA = human serum albumin) conjugate. PBMC of all subjects showed a significant proliferative response to this sugar conjugate. Howev er, the levels of interleukin (IL)-10 induced by LNFPIII-HSA were higher in groups with low and medium egg counts than those with high egg. Soluble eg g antigens (SEA) also induced IL-10 production by PBMC from infected patien ts. Interestingly, the SEA-induced IL-10 production was remarkably inhibite d by pretreatment of PBMC with free ligands of LNFPIII (monovalent form). T hese LNFPIII-pretreated PBMC displayed appreciable increase in the level of proliferation to SEA stimulation. We propose that the observed bystander i mmune potentiation rendered by free LNFPIII is due to the reduced IL-10 lev el which, presumably, up-regulate expression of co-stimulatory molecules on APC, The ensemble of results indicates that the Le(x)-containing LNFPIII i s a potent immunoreactive epitope in SEA that negatively influences PBMC re sponse against this parasite antigens via IL-10, (C) American Society for H istocompatibility and Immunogenetics, 2000. Published by Elsevier Science I nc.