Failure of Plasma from Human Schistosomiasis Mansoni Patients to Protect Mice from Schistosoma Mansoni Cercarial Challenge

Plasma samples obtained from patients with well defined Schistosoma mansoni infections, or control subjects, were passively transferred to CF1 mice. Three, 12, or 24 hours after passive transfer, the recipient and control mice were challenged with either 200 or 600 live cercariae, and the adult worm burdens or schistosomula lung recoveries, respectively, were determined 7 weeks or 6 days after challenge. None of the human plasmas afforded the recipient mice protection against the development of schistosomes. Worm and larval yields were equivalent in all cases, even though many of the patient plasmas were shown, as assessed by an in vitro eosinophil-dependent cytotoxic antibody assay, to contain high levels of antischistosomular antibody.