BACKGROUND: Cysteine endopeptidases and their inhibitors play an important role in the process of carcinogenesis. Positive correlation has been found between tumor invasiveness, its metastatic potential and the secretion of cysteine endopeptidases. Cysteine protease inhibitory activity is also altered in malignant tumors and various body fluids of patients with cancer. MATERIAL/METHODS: Total cysteine endopeptidase activity and cysteine proteinase inhibitory activity were measured in homogenates of cervical lymph node tissue surgically obtained from the larynx of cancer patients. The tissue samples were histologically examined, and each was divided into two parts: positive (PCN), with mostly cancer cells, and negative (NCN), with no cancer cells. RESULTS: In the PCNs, the levels of the assayed enzymes and their inhibitors were significantly higher than in the NCNs. The mean values of cysteine protease activity were 2.70I2.29 and 1.59I1.28 for PCNs and NCNs, respectively (p<0.005). The mean values of cysteine protease inhibitors were 9.1I8.6 and 6.1I6.3 for PCNs and NCNs, respectively (p<0.02). An altered protease-inhibitor activity ratio was also found in PCN samples compared to NCNs. CONCLUSIONS: These data suggest increased activity of cysteine peptidases and their inhibitors in the case of secondary tumor tissue. The cancer cells metastasized to lymph node tissue produce some alteration in balance between cysteine protease activity and the endogenous inhibitors of the proteases.

Keywords: Lymph Nodes - metabolism