Frequency and kinetics of polyclonal and clonal B cells in the peripheral blood of patients being treated for multiple myeloma.

Recent studies concerning the numbers of circulating clonal B cells in patients with multiple myeloma (MM) have reported conflicting data regarding the exact level and phenotype of clonal B cells and their response to treatment. In this report we document that the peripheral blood tumor burden at presentation was reduced by induction therapy to a low level, regardless of the initial tumor burden. However, the residual clonal compartment persisted before and after transplant. The level of clonal cells showed no correlation with CD19(+) cell levels. In a single patient with MM, high numbers of phenotypically aberrant clonal cells with altered CD19 expression were identified. (Blood. 2000;96:4357-4359)