Abstract
The cytochemical reaction for peroxidase is partially inhibited by methanol. The addition of a small amount of sodium nitroferricyanide to the absolute methanol causes further inhibition. The activity of peroxidase is completely suppressed by methanol containing 1% sodium nitroferricyanide and l% acetic acid. The antibody to horseradish peroxidase is much less affected by these inhibitors than horseradish peroxidase itself. By using appropriate combinations of these inhibitors and by varying the time or temperature of treatment, the activity of injected horseradish peroxidase, or of endogenous peroxidase in leukocytes, erythrocytes or normoblasts, can be much decreased or suppressed while the specific ability of the antibody to adsorb horseradish peroxidase can be preserved to a considerable extent. KCN and NaN3 inhibit peroxidase activity only moderately under conditions required for immunoperoxidase procedures, i.e., after removal of the inhibitors.