Immunoglobulin expression in B-cell lymphoma. Immunohistochemical study of 345 cases

Immunoglobulin expression was studied in a series of 345 cases of B-cell lymphoma by immunohistochemical studies and correlated with the histopathologic classification with the use of the Working Formulation. Immunoglobulin expression was present in 254 cases (74%) of B-cell lymphomas (IgM kappa, 122; IgM lambda, 82; light chain only, 40; mu heavy chain only, 10). Immunoglobulin expression occurred with the greatest frequency in lymphomas of small lymphocytic, small cleaved cell, and small noncleaved cell histologic types (93%, 100%, 100%, respectively) and occurred with the least frequency in lymphomas of large cell (cleaved and noncleaved) and immunoblastic histologic types (59% each). Other lymphomas demonstrated intermediate frequencies of immunoglobulin expression. An excess of cases expressing lambda light chain was noted overall (kappa-lambda ratio of 1.3; expected, 2.0) and was particularly evident for intermediate lymphocytic and follicular mixed histologic types (kappa-lambda ratios of 0.8 and 0.9, respectively). Immunoglobulin expression in B-cell lymphomas varies as a function of cellular differentiation as reflected in the histologic type and grade of the Working Formulation. An excess of cases expressing lambda light chain in specific histologic categories suggests the possibility that lymphocytes bearing the lambda light chain rearrangement may be more susceptible to certain types of lymphomatous transformation.