Abnormal profile of serum proteinase inhibitors in cancer patients.

We reported previously that an antitryptic glycoprotein, EDC1 (Mr 27,500), which is immunologically related to the normal serum proteinase inhibitor, inter-alpha-trypsin inhibitor (IATI), is excreted in large quantities in the urine of metastatic cancer patients. We have now measured immunoreactive titers of urinary EDC1 and five serum proteinase inhibitors (including IATI) in 16 patients with hematological cancers, 9 patients with various solid tumors, and 32 healthy subjects. The mean urinary EDC1 levels were 22-fold greater in all cancer patients as compared to normals [187.0 +/- 136.6 (S.D.) versus 8.4 +/- 8.2 mg/g creatinine; p less than 0.001]. In the cancer group, serum levels of immunoreactive alpha 1-proteinase inhibitor (also called alpha 1-antitrypsin), alpha 1-antichymotrypsin, and C1 inactivator averaged 152, 237, and 165% of the normal values, respectively (p less than 0.01). Immunoreactive alpha 2-macroglobulin levels were unchanged, and immunoreactive IATI levels were depressed (75% of the normals; p less than 0.01). The lower levels of IATI and elevated levels of EDC1 are consistent with the latter being derived from the former. In spite of the increased immunoreactive alpha 1-proteinase inhibitor level, the serum antitryptic capacity of the cancer group averaged only 50% of the normal group (p less than 0.01; range, 5 to 110% of normal average). This suggests that about 70% of the serum alpha 1-proteinase inhibitor in the cancer group is functionally inert.