CATHEPSIN-B AND CYSTEINE PROTEINASE-INHIBITORS IN BRONCHOALVEOLAR LAVAGE FLUID OF LUNG-CANCER PATIENTS

The enzymatic activity and the concentration of cathepsin B (CB), dete rmined by ELISA, and total inhibitory activity of cysteine proteinase inhibitors (CPIs) were measured in bronchoalveolar lavage fluid (BALF) of lung tumor patients (n = 49). Significantly higher CB activity and concentration was found in BALF from metastasis (n = 15), when compar ed to squamous cell carcinoma (SCC; n = 15) and small cell lung carcin oma (SCLC; n = 7). Patients with adenocarcinoma (n = 12) also secreted considerably more CB, about 14- and 3.3-fold, compared to SCC and SCL C patients, respectively. However, only tumor patients without inflamm ation were considered because the comparison of patients with lung tum ors (n = 49) and with other non-neoplastic lung diseases (n = 18) show ed no differences due to high CB in BALF of patients with inflammatory conditions, present in some patients from both groups. Immunolabeling of tumor BALF proteins revealed CB immunoreactivity at molecular size s that corresponded to the size of its precursor and mature forms, as well as to complexes with kininogen(s) and low molecular weight CPIs. Stefins A and B, but not cystatins C and S appeared in the complexes w ith CB.