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. Because the tumor did not contain discernible mast cells or other mast-cell constituents, such as histamine, it is likely that this extractable eosinophilotactic peptide was produced by the tumor in a manner analogous to the well described ectopic production of polypeptide hormones. (N Engl J Med 290:4...