Autoantibodies directed against lipid membrane components in sera of patients with malignant tumors.

Tumor-associated antigens (Ag) are expressed on neoplastic cells. Using an enzyme-linked immunosorbent assay (ELISA), an attempt was made to evaluate the autoimmune responses directed against lipid membrane components. A comparison was made of autoantibody (autoAb) levels in human sera of 684 patients with malignant tumors and those of 185 controls (healthy subjects and patients suffering from other diseases). A highly significant difference was found between the immunological binding of the groups for only one phospholipids (PL), i.e., phosphatidylinositol (PI). Using ELISA tests and PI-related compounds differing in fatty acid residue types and/or in phosphatidyl group, it was demonstrated that the hydrophilic residue is the immunodominant part recognized by the autoAb detected in sera of cancer patients.