Immune mechanisms that stimulate mouse leukocyte migration in response to schistosomula of <i>Schistosoma mansoni</i>.

Abstract

Abstract Migration of mouse peritoneal exudate cells across polycarbonate membrane filters in response to schistosomula of Schistosoma mansoni was examined in blind-well chemotaxis chambers. Schistosomula themselves were not found to contain any components capable of stimulating the migration of these cells. In contrast, cell migration was enhanced by products of immune reactions involving the interaction of schistosomula with complement or antibody plus complement. That is, neutrophil migration was stimulated in response to activation of the alternate complement pathway by schistosomula, whereas eosinophil as well as neutrophil migration was stimulated in response to complement activation via the classical pathway by antibody-coated schistosomula. Fractionation of immune mouse sera on Protein A-Sepharose indicated that the classical pathway activity was dependent on antibody of the IgG immunoglobulin class, with fractions containing IgG1 being highly effective. These results are consistent with previous in vivo findings in which the inflammatory response to schistosomula in the skin of normal mice has been observed to be primarily neutrophilic, whereas the reaction to challenge larvae in immune animals is eosinophil-enriched. Migration stimulatory activity was also produced by the interaction of schistosomula with sensitized lymphocytes. Supernatant fluids obtained from the culture of schistosomula with spleen cells from S. mansoni-infected but not normal mice were found to enhance eosinophil and mononuclear cell migration. This activity was not present in fluids from culture of schistosomula with sensitized spleen cells pretreated with anti-Thy-1 antibody plus complement, suggesting that its production is T lymphocyte dependent. Therefore, cell migration appears to be induced by a lymphokine and as such is an indication of cell-mediated immune reactivity against schistosomula.