Mallory bodies. Horseradish peroxidase: specific cytochemical and biochemical marker for alcoholic hyalin.

Horseradish peroxidase (HRP), a glycoprotein enzyme, bound specifically to Mallory bodies (MBs) in cryostat sections of autopsy liver and liver biopsies. In contrast, HRP did not bind to cryostat sections of normal liver. The specificity of HRP binding was also observed using light and electron microscopy in autopsy liver-derived subcell fractions prepared by the MB isolation procedure. In order to quantitate HRP binding, a solid phase colorimetric assay was developed. This assay involves immobilizing purified MBs or homogenized tissue fractions in glass tubes, incubating with HRP, and measuring the enzymatic activity of bound HRP. A linear relationship between MB concentration and HRP binding was observed. The assay was capable of detecting as little as 1 microgram of MB protein. The specificity of HRP binding was also investigated using the solid phase assay. The specific activity (HRP bound per milligram of protein) of purified MBs was 10 to 15 times that of a glass wool-filtered liver homogenate suggesting that the solid phase assay may be of use in monitoring the purification of MBs. HRP did not bind to normal liver homogenate even when large loads were assayed. The results of this study indicate that HRP binding, employed cytochemically, represents a rapid and facile procedure for ascertaining the presence of MBs in tissue. In some cases, those structures may not be easily visualized by conventional staining procedures. Furthermore, quantitation of MBs in tissue may be possible by using a solid phase enzyme-linked assay.