Immunoglobulin gene rearrangements in adult non-hodgkin's lymphoma

Southern blotting was employed to analyze the immunoglobulin heavy and light chain genes and the gene for the T cell receptor beta chain in genomic DNA derived from the tumor specimens of 120 adults with pathologically classified and immunotyped non-Hodgkin's lymphoma and B cell chronic lymphocytic leukemia. In a consecutive series of 100 patients, one or two rearranged heavy chain genes could be detected in each of the 80 samples expressing clonal surface immunoglobulin. The kappa gene was rearranged in 70 percent of kappa-bearing tumors and in 23 percent of lambda-bearing specimens. Furthermore, a rearranged immunoglobulin gene was also observed in 21 of 29 lymphomas (nine from the consecutive series and 20 selected for surface immunoglobulin-negative status) in which B cell lineage was in doubt because of absent clonal surface immunoglobulin. These findings indicate that most cases of lymphoma and lymphocytic leukemia in adults are of B cell lineage, even when phenotypic evidence is inconclusive. The exceptional cases (only 3 percent in the consecutive series) were of either follicular lymphoma or diffuse large cell (histiocytic) lymphoma subtype; the lineage in cases of diffuse lymphocytic lymphoma or chronic lymphocytic leukemia was never in doubt. Although the convenience of surface marker analysis assures its continuing clinical application, gene study resolves indeterminate cases and extends the understanding of the pathogenesis of lymphoproliferative disease.