Low molecular weight eosinophil chemotactic factor (ECF) in the serum of murine schistosomiasis japonica.

Eosinophil chemotactic activity was detected in the serum obtained at an acute stage of murine schistosomiasis japonica. Gel filtration of the dialyzable fraction of the serum on Sephadex G25 showed that the chemotactic component had an apparent molecular weight of less than 1,000. It was stable to heating, but was sensitive to pronase or carboxypeptidase A digestions, indicating its peptide nature. Eosinophil chemotactic activity of the dialysate of the serum from mast cell-deficient W/Wv mice infected with Schistosoma japonicum was far less than that from normal littermate +/+ mice, although the titers of specific IgE antibody to soluble egg antigen in the serum measured by passive cutaneous anaphylaxis was comparable between them. These results suggest that at least some part of low molecular weight ECF in the circulation seems to be a ECF-A derived from mast cells. Possible biological significance of circulating ECF in schistosomiasis has been discussed.