Correlations Between Gene Rearrangements and Immunoreactivity of Reed-Sternberg Cells in Paraffin Sections: A Genotypic and Phenotypic Study of 14 Cases of Hodgkin's Disease

Recent immunohistological analyses using monoclonal antibodies (MAbs) in paraffin sections have shown that Reed-Sternberg cells (RSC) sometimes express B-cell markers, thereby suggesting a lymphoid origin in at least some cases of Hodgkin's disease (HD). In order to clarify the meaning of RSC immunoreactivities in paraffin sections, 14 cases of HD selected on the basis of a minimal RSC content of 5% (6 with mixed cellularity and 8 with nodular sclerosing HD) were B5 fixed, paraffin embedded and analysed by immunophenotyping with a panel of MAbs (LCA, MB1, MB2, L26, LN2, UCHL1, MT1, MT2, LeuM1, Ber-H2). Prior to fixation, a part of each specimen was frozen and submitted to genotypic analysis using immunoglobulin (Ig), T-cell receptor (TCR) gamma and TCR beta genes probes. RSC were strongly positive with LeuM1, BerH2 and LN2 in all cases and weakly positive with L26 in 4 cases and MB2 in 1 case. Many MT1-UCHL1 positive small lymphocytes were densely distributed close to RSC in all cases. The 14 cases retained a germline configuration with all enzyme-probe combinations tested. This finding cannot only be explained by the low number of RSC, which represented at least 5% of the cell population. Thus, neither the clonal nor the lymphoid nature of our HD cases could be determined unequivocally. LN2, L26 and MB2 expression do not correlate with Ig gene rearrangements and therefore cannot be considered as an argument supporting the B-cell derivation of RSC.