Immunoglobulin Gene Rearrangement of Lymphoid Malignancies: Application of the PCR Technique to Formalin-Fixed, Paraffin-Embedded Tissues

Abstract

Every B-lymphocyte carries a unique sequence of the immunoglobulin heavy chain (IgH) gene, which serves as a marker for tumor cells derived from clonal B-lymphocyte expansion. Southern blot analysis for IgH gene rearrangement is not suitable for small biopsies and formalin-fixed, paraffin-embedded tissues. We aimed to assess the application of PCR techniques to demonstrate clonal IgH gene rearrangement in B-cell non-Hodgkin's lymphoma (B-NHL). A series including 119 B-NHL, 10 T-cell NHL, 6 reactive lymphoid hyperplasia, and 15 non-lymphoid malignancies were examined. DNA was extracted from paraffin-embedded tissues by proteinase K digestion. A semi-nested PCR amplification targeting two framework regions (Fr2A and Fr3A) and the joining region (JH) of the variable gene segment of the IgH gene was performed. Clonal IgH gene rearrangement was detected in 30% and 63% of B-NHL with Fr2A and Fr3A assays, respectively, and 74.8% when both assays were combined. Clonal IgH gene rearrangement was not demonstrated in any of the reactive lymphoid hyperplasia and non-lymphoid malignancies. However, 20.0% of the T-NHL showed clonal IgH gene rearrangement. Differences were noted among different subtypes of B-NHL. Clonal IgH gene rearrangement was detected in all of the low-grade B-NHL, except follicular lymphoma. High-grade B-NHL generated heterogeneous results.