Immunophenotypic and genotypic characterization of chronic lymphocytic leukemia patients from northern Italy

Background and methods: Immunoglobulin (Ig) gene expression and rearrangements provide information about cell lineage, clonality and differentiation of neoplastic lymphoid cells. We performed flow cytometry and Southern blot analysis in 25 patients with chronic lymphocytic leukemia (CLL) from the Po River delta region (Northern Italy), in order to correlate surface immunological phenotype and heavy and light chain gene rearrangements with clinical stages. Results: In these 25 CLL cases, as in the larger group of 165, k-positive (k+) patients were more frequent than lambda-positive (lambda +) ones by a ratio of 59:41, with a predominance of lambda + in stage II (46:54) and of K+ in stage IV (77:23). However, the survival behavior of lambda + and k+ patients was not statistically different. Ig gene rearrangements were found in all patients in accordance with the immunophenotype. When Ig gene analysis was performed on two different occasions in 7 of the 8 who received chemotherapy, there was an increase in the percentage of the germline band. This variation was inversely related to changes in WBC count. In the treated subject who showed a reduction of both WBC count and the germline, there was rapid disease progression and short survival. Conclusions: Analysis of Ig gene rearrangements in our CLL patients demonstrated: i) the monoclonality of neoplastic cells; ii) no correlation between rearrangements and clinical stages, and iii) that this analysis may be a useful tool in evaluating biological behavior in selected CLL cases showing a discrepancy between hematological data and clinical response to therapy.