IMMUNOGLOBULIN LIGHT-CHAIN STAINING IN PARAFFIN-EMBEDDED TISSUE USINGA HEAT MEDIATED EPITOPE RETRIEVAL METHOD

We have compared light chain immunohistochemistry in reactive lymphoid tissue and a series of paraffin-embedded B-cell lymphomas using stand ard trypsin digestion with a heat mediated epitope retrieval method. F ifty-seven B-cell lymphomas (18 high grade, 29 low grade and 10 cases of nodular lymphocyte predominance Hodgkin's disease), two reactive ly mph nodes and eight tonsils fixed for known times between 12 h and 2 y ears were studied. Paraffin-embedded tissue was stained with polyclona l anti-kappa and anti-lambda antibodies. For each antibody staining wa s performed on two sections, one treated with trypsin digestion and on e with microwave heating. Sections were scored from 0 to + + + with 0 representing poor staining and + + + excellent staining. A score of + was considered satisfactory. Light chain restriction was recorded if present. Satisfactory staining was obtained in 34/59 cases using tryp sin digestion and 56/59 cases using heat retrieval. Light chain restri ction was demonstrated in 32/57 (56%) B-cell lymphomas using trypsin d igestion and 52/57 (91%) using heat retrieval. Satisfactory staining w as obtained in tonsils fixed for up to 48 h using trypsin digestion an d up to 2 years using heat retrieval. We have shown that for light cha in immunostaining a heat mediated epitope retrieval method produces mo re consistent and satisfactory results and is effective over a greater range of fixation times than traditional trypsin digestion.