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Glutathione transferase activity in the cytosolic fractions of human lung tumors was found to be significantly higher than that present in the corresponding non-tumor cytosolic fractions. The relative activities of 'cationic', 'near-neutral' and 'acidic' glutathione transferases of both tumor and non-tumor cytosols were estimated after isoelectric focusing. More than 90% of activity in both tumor and non-tumor cytosols was found to be associated with the 'acidic' (pI 4.6) activity peak. In the chromatogram of tumor tissues the activity associated with the 'acidic' peak was found to be increased in comparison with non-tumor tissues. When the protein fractions associated with the 'acidic' peak of both tumor and non-tumor tissues were tested against the antibodies raised against human placenta transferase (transferase pi) a continuous precipitin line was obtained. An increased amount of immunoreactive glutathione transferase was also found in tumor cytosols as compared with non-tumor cytosols. Thus, our studies indicate that the predominant glutathione transferase of human lung appears to be electrophoretically and immunologically very similar or identical to transferase pi and that the elevation of transferase activity measured in the lung tumor cytosols was mainly due to increased quantity of this isoenzyme.

Glutathione transferase (GST) activity in the cytosolic fractions of four renal cortex tumors was found to be lower (1.85-3.4 times) than that present in the corresponding non-tumor cytosolic fractions. Glutathione transferase of both tumor and non-tumor kidney was purified by affinity chromatography and separated into five peaks at pH 4.7, 8.0, 8.4, 8.7 and 9.0 by isoelectric focusing. In the chromatogram of tumor tissues, the activity associated with the 'acidic' peak increased significantly, whereas the activities associated with 'basic' peaks all decreased in comparison with the corresponding peaks of non-tumor tissues. The acidic GST of human kidney is immunologically identical to GST pi, confirming that it is a good marker for human tumors.

Selenium, glutathione peroxidase, glutathione reductase and glyoxalase I have been measured in normal and neoplastic human adult lung tissues. Interindividual variations of enzyme activities and selenium content in both tumour and non-tumour tissues were considerable. From the measurements of glutathione peroxidase activity with both hydrogen peroxide and cumene hydroperoxide it was deduced that human tumour and non-tumour lung tissues are devoid of the selenium-independent enzyme. In general, a significant increase in the activity of glutathione peroxidase and glutathione reductase was found in tumour. Glyoxalase I in tumour was as high as in non-tumour samples. Mean selenium concentration tended to be higher in tumour than in non-tumour specimens. When a comparison was made between normal and neoplastic tissue of the same individual, glutathione peroxidase, activity was found to be higher in tumour in 19 cases out of 24 and glutathione reductase in 17 out of 22. In 15 cases out of 18 the selenium levels were found to be higher in tumour. It was concluded that changes in the factors involved in anti-oxidative protection actually occur in human lung tumour tissues.