The blood B-cells and bone marrow plasma cells in patients with multiple myeloma share identical IgH rearrangements.

Previous reports have described the phenotypic and functional properties of monotypic late stage B cells in the blood of patients with multiple myeloma and have speculated that these B cells represent a malignant circulating component of myeloma. Here we show that blood B cells have IgH rearrangements identical to those expressed by the bone marrow plasma cells by using Ig Fingerprint and Allele-Specific Oligomer (ASO) polymerase chain reaction (PCR) methods. DNA from purified blood B cells and bone marrow plasma cells taken at the same time, and blood B cells taken at subsequent patient visits was amplified using consensus IgH primers, or ASO primers. In 10/16 patients, a single IgH rearrangement was amplified from the bone marrow plasma cells. In all 10 of those patients the same clonotypic rearrangement was amplified from the purified blood B cells. The relationship of these clonal blood B cells to the malignant bone marrow plasma cells remains undetermined.