Horseradish peroxidase conjugates are prepared by a modified Nakane and Kawaoi procedure (J. Histochem. Cytochem. 1974. 22, 1084). Peroxidase conjugates are widely applicable, being suitable for immunohistochemistry, Western blotting, and ELISA.

Alkaline phosphatase conjugates are prepared by a modified method of Avremeas et al., Scand. J. Immunol. 1978. 8 (Supple.7), 7. Resulting conjugates are complexes, which are high titered but also high molecular weight. They are sensitive reagents for solid-phase immunoassays such as ELISA and Western blotting. Although alkaline phosphatase conjugates have been used for immunohistochemistry, tissue penetration may be limited by their size.

Affinity-purified anti-horseradish peroxidase and conjugates are available for detection of horseradish peroxidase, or for amplification of HRP-containing reagents. For immunostaining of mammalian cells, an advantage of using anti-horseradish peroxidase is reduced background, since the antibody does not recognize the endogenous peroxidase-like enzymes found in those cells.