Rearrangements of Immunoglobulin Light Chain and Heavy Chain Constant Region Genes in B-cell Malignancies

Abstract

We analyzed immunoglobulin (Ig) gene rearrangements in 69 patients with B-cell malignancies by Southern hybridization. We used 5 probes which covered J_H 5'Sμ and Sγ3 loci of the Ig heavy (IgH) chain gene, and Cκ and κde loci of the Ig light (IgL) chain κ gene, respectively. DNA rearrangements were observed in 68 out of the 69 patients using the J_H probe. In 97% (33/34) of patients with non-Hodgkin's lymphoma (NHL), 100% (5/5) of chronic lymphocytic leukemia (CLL), 42% (10/24) of non-T cell acute lymphoblastic leukemia (non-T ALL), and in 0% (0/4) of chronic myelogenous leukemia lymphoid crisis (CML-LBC), the rearrangements were detected by Cκ and/or κ de probes. Furthermore, the genotype of the light chain was defined by rearrangement patterns of these 2 probes.
The by using the 5'Sμ-probe, class switch recombinations were detected in 76% (25/33) of NHL, 20% (1/5) of CLL, 17% (4/24) of non-T ALL, and in 0% (0/4) of CML-LBC. Among them, 1 case of IgM NHL and 3 cases of double bearer NHL had rearranged on both IgH alleles by the constant region. The results of this study indicate that genotypes correspond well to phenotypes of B-cell malignancies and that the determination of genotype will be useful for making an exact diagnosis of B-cell malignancies.