Serum inhibitory effect on myeloperoxidase in human cancer

The myeloperoxidase level is strongly depressed in leucocytes from cancer patients (-59%). Moreover sera of the same subjects induce a significant decrease in the myeloperoxidase activity of healthy subjects' leucocytes (-43%). We have found no convincing evidence of any correlation between the level of the inhibitory effect of sera and the tumour type. The fact that sera from cancer patients interfere with neutrophil responses in this way does not exclude the possibility that abnormal cellular functions were also operative.