Improved immunohistochemical localization of tissue antigens using modified methacarn fixation.

Detailed comparative studies have been carried out using a wide range of aqueous and nonaqueous based fixatives in order to select the optimal fixation schedule for the immunohistochemical localization of four antigens: type IV collagen, actin, Factor VIII, and epithelial membrane antigen (EMA). Modified methacarn fixation provides an ideal combination of maximum staining and morphological preservation for these antigens. Enhanced immunoreactivity with this fixative was also noted for a broad spectrum of antigens, including myoglobin, glial fiber acidic protein, keratin, myosin, laminin, prostatic acid phosphatase, alpha-fetoprotein, and carcinoembryonic antigen. Although it is not recommended for most cell surface antigens, this fixative may have a definite place in diagnostic surgical pathology.