Immunohistochemistry of fresh-frozen lymphoid tissue with the direct immunoperoxidase technic.

Recent evidence suggests that immunofluorescence is superior to immunohistochemistry for the study of lymphomas, since the latter procedure often results in identification of polyclonal cytoplasmic immunoglobulins or negative immunostaining in non-Hodgkin's lymphomas marking monoclonal with immunofluorescence. However, immunohistochemical studies are usually applied to paraffin-embedded tissues. A modified direct immunoperoxidase procedure using fresh-frozen cryostat tissue sections, short incubation with peroxidase-labeled antikappa and antilambda antisera, and chromogens chemically unrelated to benzidine was developed. Non-Hodgkin's lymphomas previously characterized by direct immunofluorescence showed monoclonal surface membrane-associated light chains outlining each neoplastic cell. Follicular (nodular) lymphomas were characterized by monoclonal light chains in neoplastic nodules with compressed negative or polyclonal rims. Diffuse non-Hodgkin's lymphomas demonstrated diffuse individual cellular monoclonal staining. Five normal lymph nodes showed polyclonal immunostaining of follicular centers. The immunostained slides resulting from this procedure are permanent preparations amenable to counterstaining.