Abstract
The effects of fixatives on the antibody and horseradish peroxidase (HRP) activities in the immunocytochemical system were investigated quantitatively by using a model of polyacrylamide gel films containing proteins such as goat γ-globulin, anti-HRP guinea pig antiserum or HRP. The activity of the anti-HRP antibody was measured indirectly by staining the HRP coupled with its antibody in the gel films. About 40% of the antibody activity was lost by fixation in 2.5% glutaraldehyde and approximately 35% in 4% formalin. The inactivation of HRP by the refixation in glutaraldehyde or formalin was also examined. The loss of HRP activity was inversely related to the concentration of the fixatives. The fixation in 2.5% glutaraldehyde and 4% formalin inhibited HRP activity 35% and 40%, respectively. The inactivation occurred generally within 40 min of the refixation.