Phenotypic analysis by flow cytometry of surface immunoglobulin light chains and B and T cell antigens in lymph nodes involved with non-Hodgkin's lymphoma.

The objective of this study was to demonstrate the diagnostic usefulness of flow cytometric analysis of surface membrane immunoglobulin light chain and monoclonal antibody reactivities in B cell non-Hodgkin's lymphoma. For this purpose, lymph node cell suspensions from 80 patients (20 normal lymph nodes, 11 lymph nodes with benign lymphoid hyperplasia, and 47 lymph nodes with B cell non-Hodgkin's lymphoma) were studied to detect the expression of surface B and T cell differentiation antigens recognized by a panel of monoclonal antibodies (anti-Leu-1, anti-Leu-5, anti-HLA-DR, J-5, anti-BL-1, anti-BL-2, and anti-BL-7). The clonal excess calculation, percent kappa-positive minus percent lambda-positive/percent kappa-positive plus percent lambda-positive cells per discrete level of fluorescence intensity, was used to study the clonality of surface membrane immunoglobulin light chain expression. Among the BL surface antigens, BL-7 proved to be most consistently expressed in B cell non-Hodgkin's lymphoma (79 percent). It was also present in 57 percent of lymph nodes with benign hyperplasia. No significant relationships were detected between the patterns of reactivity with the anti-BL monoclonal antibodies and histologic subtypes, although the small number of cases tested in each category precludes any definitive conclusions. Immunophenotypic heterogeneity within subgroups was also observed with expression of the other antigens examined. Monoclonal expression of surface membrane immunoglobulin light chain was seen in 43 of 47 (91 percent) of lymph nodes with non-Hodgkin's lymphoma, three of 11 (27 percent) hyperplastic lymph nodes, and one of 22 (4 percent) normal lymph nodes. When the presence of BL-7 and clonal excess was examined as a panel, 83 percent of B cell non-Hodgkin's lymphomas were positively identified, whereas one normal lymph node and no hyperplastic lymph nodes gave positive results. The simultaneous presence of clonal excess and BL-7 can be a useful diagnostic aid in the differentiation of lymphomatous from hyperplastic lymph nodes. Cytofluorimetry provides a rapid, objective, and reproducible technology to confirm the diagnosis of lymph node involvement in B cell non-Hodgkin's lymphoma.