The presence of eosinophil‐activating mediators in sera from individuals with Schistosoma mansoni infections

Abstract

IgG antibodies and eosinophils kill schistosomula of Schistosoma mansoni in vitro, and there is now evidence to suggest that the main factor that contributes to the expression of purified IgG effector function is the degree of activation of the donor's eosinophils. This study was designed to identify serum-derived activating factors in sera from individuals infected with S. mansoni. Such activating factors may be responsible for enhancing eosinophil cytotoxicity against schistosomula. Serum-borne mediators were prepared by fractionation of sera from infected individuals by gel filtration high-performance liquid chromatography. The eosinophil-stimulating activity of these mediators was assayed by a new method which depends on the increased expression of the CR3 alpha chain (CD11b) on the surface of activated eosinophils. Sera from infected individuals exhibited different levels of eosinophil activation, and activation appeared to be due to several serum factors, including interleukin 5. In conclusion, our results suggest that eosinophil-activating factors present in infection sera may not only be responsible for enhancing eosinophil cytotoxicity but also be necessary for its expression.

Expression of cell surface adhesion molecules by peripheral blood eosinophils during Trichostrongylus colubriformis infection in sheep

“…The decreased MFI of CD11a and a trend for decreased MFI of CD44 on mammary exudate eosinophils elicited by T. colubriformis antigens suggests that systemic activation of eosinophils was occurring during the course of infection and vaccination. These findings are in accord with the observation of activation of blood eosinophils by intravascular parasites such as Schistosoma mansoni 9 and Onchocerca volvulis. 10 The importance of these changes in adhesion molecule expression by intravascular eosinophils on cell functions and immunity to T. colubriformis requires further study.…”

“…Eosinophils in sputum from asthmatics have increased expression of CD11b, and decreased expression of CD62L 8 . In severe allergic reactions 8 and parasitic infections 9 , 10 similar changes may be seen on eosinophils in peripheral blood. Intravascular activation may lead to systemic sequellae and modify the capacity of cells to migrate to extravascular sites 11 …”

Involvement of complement and fibronectin in eosinophil‐mediated damage to Nippostrongylus brasiliensis larvae

“…It is well accepted that IL‐5 prolongs the survival of eosinophils in vitro , and that it upregulates eosinophil functions, resulting in enhancement of helminthotoxic activity (Walsh et al . 1990, Mazza et al . 1991).…”

“…It is well accepted that IL-5 prolongs the survival of eosinophils in vitro, and that it upregulates eosinophil functions, resulting in enhancement of helminthotoxic activity (Walsh et al 1990, Mazza et al 1991. Hartnell et al were able to demonstrate that the activation of eosinophils, measured by CR3 expression, was saturated at 300 U/ml of rIL-5, suggesting the maximum dose for the activation of eosinophils (Hartnell et al 1992).…”