Clonality analysis for antigen receptor genes: Preliminary results from the biomed-2 concerted action PL 96-3936

The diagnosis of lymphoproliferative disorders is based on histopathology and immunophenotyping, and most cases can be concluded without further techniques. However, in a number of cases the differential diagnosis between a reactive process and malignant lymphoma is difficult, and molecular techniques can be helpful. In particular, assessment of clonality is a useful adjunct, because mature lymphocytes have rearranged immunoglobulin or T-cell antigen receptor genes, and thus almost all malignant lymphomas have a clonal rearrangement of at least 1 of these antigen receptor genes. Assessment of clonality can be performed using Southern blot analysis with several restriction enzymes and many different probes. This is a reliable method, but it requires large amounts of high-molecular-weight DNA and is time-consuming. Several different polymerase chain reaction (PCR)-based methods have been described, generally using consensus primers for only a few of the rearranged loci. This method is rapid but less reliable, because incomplete rearrangements can be missed and also because mutations in the regions of primer annealing can cause negative results. This is especially common in lymphomas of germinal center (GC) origin and also to a lesser extent in post-GC lymphomas. We therefore decided to develop and test new primer sets for all relevant loci of the B-cell and T-cell receptor genes.