Abstract
Lactate dehydrogenase (LDH) is considered to be a intracytoplasmic key enzyme of glycolysis. It is generally accepted that in malignant tissue, LDH-M subunits is dominant. In this report cancer cells in sputum of bronchogenic carcinoma were observed by LDH stain, and analyzed on serum LDH and LDH isozyme patterns.
The LDH activity were visualized by conversion of Nitro-Blue-Tetrazolium into insoluble formazan (2H). For this purpose the Urea Inhibition Test was done by 2.6 mol urea in the staing solution for identification of the LDH-M subunits, compared with loss of LDH activity and total LDH activity.
By the LDH stain, diformazan positive cells were observed in the sputum of normal volunteers. Generally they hardly showed loss of LDH activity by the Urea Inhibition test. On the other hand cancer cells stored diformazan in their cytoplasm frequently, and they were revealed loss of LDH activity by the Urea Inhibition Test. The LDH-M subunits, which increased in an anerobic state, can be regarded as existing in those cells. From the facts described above, we may conclude that LDH-M subunits are recognized as a good method to distingwish malignant cells from normal cells in the sputum cytology.
