Immunity in human schistosomiasis mansoni: prevention by blocking antibodies of the expression of immunity in young children

Abstract

SUMMARYA total of 129 children were treated forSchistosoma mansoniinfections, and followed for intensity of reinfection at3-monthly intervals over a 21-month period. Blood samples were taken before treatment and at 5 weeks and 6, 12 and 18 months after treatment. This paper presents a statistical analysis of the relationship between various immune responses and subsequent reinfection. Responses analysed were: blood eosinophil levels; IgE antibodies against schistosomulum antigens; IgG antibodies mediating eosinophil-dependent killing of schistosomula; antibodies inhibiting the binding to schistosomulum antigens of two rat monoclonal antibodies that also recognize egg antigens; the levels of anti-adult worm and of anti-egg (total, IgM and IgG) antibodies; and IgM anti-schistosomulum antibodies. Results for each assay were well correlated for each of the five separate blood samples. None of the assays were predictive of resistance to reinfection, butsusceptibilityto reinfection was strongly correlated with results in the preceding blood samples for total anti-egg antibodies and the inhibition of binding of one of the two monoclonal antibodies. Further analysis also revealed a correlation between reinfection intensities and both IgM anti-schistosomulum antibodies and IgM and IgG anti-egg antibodies. These results are consistent with the hypothesis that early infections elicit the development, in response to egg antigens, of antibodies that block immune mechanisms directed against schistosomula. Blocking antibodies may be IgM, but might also be of an ineffective IgG isotype. The existence of such antibodies in young children would explain the slow development of immunity in the face of a range of detectable, potentially protective immune responses.

Antibodies to Keyhole Limpet Hemocyanin Cross-React with an Epitope on the Polysaccharide Capsule of Cryptococcus neoformans and Other Carbohydrates: Implications for Vaccine Development

“…In addition, KLH cross-reacts with nonprotective S. mansoni epitopes, and not the protective ones (10). Just as GXM contains protective and nonprotective epitopes, similar findings have been reported with other carbohydrate Ags (14,15). There is a possibility that other, yet unknown, nonprotective epitopes that cross-react with KLH exist on carbohydrates of other organisms, possibly resulting in deleterious effects.…”

“…In the case of C. neoformans, these epitopes have been defined based on their reactivity with mAbs that do or do not prolong the life of mice lethally infected with C. neoformans (12,13). In addition, there is evidence that Abs directed against nonprotective epitopes of the polysaccharide capsule of Schistosoma mansoni, N. meningitidis, and C. neoformans can block the efficacy of protective Abs and even enhance infection (11)(12)(13)(14)(15).…”

The impact of repeated treatment with praziquantel of schistosomiasis in children under six years of age living in an endemic area for Schistosoma haematobium infection

“…These higher rates of reinfection are in part related to higher levels of water contact by children, a feature characteristic of the majority of endemic settings. While the severe clinical forms of schistosomiasis infection may take many years to develop, there is general agreement that targeting treatment to children can make a considerable impact on the development of pathology (Kloetzel 1967, Sturrock 1987. The use of chemotherapy to control schisto-somiasis is usually based on annual rounds of screening and treatment.…”

Étude par la réaction d’mmunofluorescence des anticorps dirigés contre les antigènes de l’épithélium intestinal deSchistosoma mansoni

“…Le SEA est composé de protéines, de polysaccharides et de glycopro téines. Il est capable d'entraîner une lymphoprolifération et une production de lymphokines in vitro (12) (10). Un anti corps monoclonal dirigé contre le MSA1 donne lieu au phénomène de précipitation périovulaire observé il y a de nombreuses années par Oliver-Gonzales (19) avec des sérums de sujets bilharziens riches en anticorps.…”