Involvement of the B-lymphoid system in chronic myelogenous leukaemia

Abstract

Studies with glucose-6-phosphate dehydrogenase (G6PD) iso-enzymes have demonstrated that chronic myelogenous leukaemia (CML) is a clonal disorder of pluripotent haematopoietic stem cells which are capable of differentiation to myeloid cells, monocytes, erthrocytes and platelets¹. It has been observed recently in G6PD heterozygous patients with chronic phase CML that the non-E-rosetting lymphocytes were restricted to a single enzyme type, indicating that some lymphoid cells must also arise from the leukaemic clone². Surface or cytoplas-mic immunoglobulin could be detected in up to 46% of the cells of these isolated non-T-lymphocyte populations, which suggested that cells from the CML clone were capable of differentiating into B lymphocytes. To investigate this further, we established Epstein–Barr virus (EBV)-transformed B-lymphoblastoid cell lines derived from patients with CML and studied chromosomes and G6PD to determine whether progenitor B lymphocytes for any of the cell lines had originated from the CML clone. We report here direct evidence that immunoglobulin-synthesizing B lymphocytes can arise from the CML stem cell clone.