Tumor-Associated Eosinophilotactic Factor

Abstract

In an attempt to understand the association of a malignant tumor and marked peripheral blood eosinophilia, a tumor-derived factor was sought. A peptide of approximately 500 molecular weight, preferentially chemotactic for eosinophils, was extracted from a large-cell anaplastic carcinoma of the lung removed from a patient with eosinophilia both peripherally and within the tumor. This peptide was indistinguishable from the previously described eosinophil chemotactic factor of anaphylaxis, a mast-cell granule-associated mediator of immediate-type hypersensitivity, in terms of size, stability in acid or base, resistance to trypsin and chymotrypsin and susceptibility to pronase and subtilisin digestion.