Ecdysteroids are compounds related to 20-hydroxyecdysone, the insect moulting hormone. Surprisingly, they have been found in serum and urine of patients infected with helminths. In these cases, the substances are assumed to be produced by the parasites and, therefore, might be used as a marker of parasitic infection. Thus, we need to know exactly which species, at which developmental stage, can release ecdysteroids in such large quantities that they could be detected in the biological fluids of the host. Large-scale investigations must, accordingly, be devoted to the major species of helminths. In the present study, we examined 100 African patients with Loa loa and/or Mansonella perstans microfilaraemia. About 70 of them had high levels of ecdysteroid-like materials in serum or urine. In contrast, uninfected patients and European controls had much lower concentrations. However, the ecdysteroid titres did not reflect the concentration of microfilariae actually present in the blood, and some heavily infected patients were even negative. Nevertheless, the most important point was that high ecdysteroid levels in man were always associated with a pathological condition. The precise significance of the phenomenon should be determined.

Adult↗

PubMedDate not supplied

Characterization of immunoreactive TNF alpha molecules in the gastropod Biomphalaria glabrata.

In recent years, several studies have demonstrated the existence of cytokine-like molecules in invertebrates, therefore suggesting that cytokines may have been conserved throughout evolution. In this study, we investigated the presence of immunoreactive TNF alpha (ir TNF alpha) in the gastropod mollusc Biomphalaria glabrata, the specific intermediate host for the trematode Schistosoma mansoni. Immunocytochemical study indicated the presence of ir TNF alpha in mollusc hemocytes corresponding to a 53-kDa molecule detected by western blot analysis. Using ELISA tests, we demonstrated the presence of substantial amounts of ir TNF alpha in hemolymph, that were significantly decreased during the S. mansoni infection. The possible role of ir TNF alpha in the regulation of mollusc immune functions and in the host-parasite relationship is discussed.

Animals↗

PubMedDate not supplied

Improvement of the T-cell response to a non-immunogenic peptide by its tandem association with a highly efficient T-helper peptide.

The 45-69 peptide, an helper T-cell epitope derived from HIV nef protein, is strongly immunogenic. A T-cell proliferative response was observed following immunization of Lou/M rats with 45-69 peptide administered in low dose and without any adjuvant. It is already known that the T-cell response to the 115-131 peptide of Sm28GST antigen, a protein of the parasite Schistosoma mansoni, requires the presence of a carrier or the use of peptidic constructs. We demonstrate here that a T-cell response against the 115-131 peptide can be obtained in the absence of adjuvant using peptidic constructs (115-45 and 45-115 peptides) resulting from tandem synthesis of 115-131 and 45-69 peptides. A covalent association of both peptides is necessary, since the co-injection of 45-69 and 115-131 peptides is not sufficient to induce a detectable anti-115-131 T-cell response. The mutual orientation between the respective tandem peptides (45-115 and 115-45) is critical for the T-cell response. These peptidic constructs possess distinct properties of antigenicity and immunogenicity but both allowed to reveal the existence of a 115-131 specific T-cell response normally undetectable using 115-131 peptide alone. This immunopharmacological approach should be useful in the rational design and construction of vaccines.

Adjuvants, Immunologic↗

PubMedDate not supplied

Improvement of the T-cell response to a non immunogenic peptide by its tandem association with a highly efficient T-helper peptide.

The 45-69 peptide, an helper T-cell epitope derived from the HIV nef protein is strongly immunogenic. A T-cell proliferative response was observed following immunization of Lou/M rats with 45-69 peptide administered in low dose and without any adjuvant. It is already known that the T-cell response to the 115-131 peptide of Sm28GST antigen, a protein of the parasite Schistosoma mansoni, requires the presence of a carrier of the use of peptidic constructs. We demonstrate here that a T-cell response against the 115-131 peptide can be obtained in the absence of adjuvant using peptidic constructs (115-45 and 45-115 peptides) resulting from tandem synthesis of 115-131 and 45-69 peptides. A covalent association of both peptides is necessary, since the coinjection of 45-69 and 115-131 peptides is not sufficient to induce a detectable anti-115-131 T-cell response. The mutual orientation between the respective tandem peptides (45-115 and 115-45) is critical for the T-cell response. These peptidic constructs possess distinct properties of antigenicity and immunogenicity but both allowed to reveal the existence of a specific T-cell response normally undetectable using 115-131 peptide alone. This immunopharmacological approach should be useful in the rational design and construction of vaccines.

Adjuvants, Immunologic↗