Immunoglobulin gene rearrangement as a diagnostic criterion of B-cell lymphoma.

We describe the use of the Southern blot hybridization technique to diagnose B-cell lymphoma by detecting clonal immunoglobulin gene rearrangements in lymph node and other biopsy tissues. DNA was isolated from a wide variety of neoplastic and non-neoplastic specimens and analyzed for the presence of rearranged immunoglobulin genes using radiolabeled DNA probes specific for the heavy- and light-chain immunoglobulin constant region genes. Among the specimens examined, clonal immunoglobulin gene rearrangements were found only in biopsy samples of B-cell lymphoma and not in samples containing reactive lymphoid processes or non-B-cell cancers. In lymphomas, the presence of rearrangements for either the kappa or lambda light-chain gene correlated with expression of one or the other of these chains when cellular immunoglobulins could be detected by frozen-section immunophenotyping techniques. The analysis of immunoglobulin gene rearrangements offers several advantages over conventional diagnostic methods for lymphomas, including improved sensitivity in detecting minor populations of neoplastic lymphocytes composing as little as 1% of the total cell population. In addition, clonal immunoglobulin gene rearrangements are demonstrable in a subset of lymphomas that lack detectable surface or cytoplasmic immunoglobulin, thus offering positive evidence for both malignancy and the B-cell origin of these tumors. Our studies indicate that detection of immunoglobulin gene rearrangements is a valuable method for diagnosis and classification of various lymphoproliferative disorders that are difficult to evaluate histologically or that lack distinctive antigenic markers.