Murine alloantigen acquisition by Schistosoma mansoni: presence of H-2K determinants on adult worms and failure of allogeneic lymphocytes to recognize acquired MHC gene products on schistosomula.

Live, adult Schistosoma mansoni, recovered from the hepatic and mesenteric veins of C3H/Crgl (H-2k) mice, displayed H-2 antigens on the tegumental surface. Alloantisera, specific for an H-2Kk gene product (specificity 23), bound to the tegument of adult worms, as demonstrated by the binding of the FITC-labeled Staphyloccus aureus to the parasite pretreated with the alloantiserum, whereas worms from B10 mice (lacking specificity 23) were negative. This is the first demonstration of the acquisition of H-2 antigens by adult S. mansoni. In contrast, formalin-fixed worms, although capable of binding IgG from serum of infected mice, were not shown to bear major histocompatibility gene products, indicating that detection of these antigens was formalin sensitive. In addition, schistosomula bearing H-2 antigens did not stimulate naive, allogeneic lymphocytes in a culture analogous to a mixed lymphocyte reaction over a 2- to 6-day period or in a dose-dependent fashion. Unresponsiveness could not be accounted for by cell death in the presence of schistosomula, because viability of responder cells was unaffected by the cocultured larvae over the 2- to 6-day period of observation.