Expression of CD44 isoforms on isolated bone marrow plasma cells and peripheral CD19(+) B cells of patients with multiple myeloma and healthy individuals

The expression of certain isoforms of CD44 was shown to correlate with aggr essiveness and metastatic potential of various tumour types. We analysed th e expression of the adhesion molecule CD44 and its variant domains (v6, v7, v7/8, v10) on isolated bone marrow (BM) plasma cells and peripheral blood (PBL) CD19(+) B cells of 21 patients with MM and 15 healthy donors. B cells and plasma cells were isolated by immunomagnetic sorting and analysed by t wo-colour flow cytometry. The expression of CD44 isoforms was significantly higher on PBL B cells of patients with MM than in healthy controls. The el evated expression of CD44 isoforms (v6, v7/8, v10) on PBL B cells correlate d with reduced overall survival in MM. CD44 isoforms were more strongly exp ressed on "larger", activated B cells. Furthermore, CD44 isoforms were foun d to be simultaneously expressed with CD38(hi) and CD56 on both, B lymphocy tes and plasma cells of patients with MM. The determination of CD44 isoform s on circulating B cells may be helpful in defining prognostically unfavour able subgroups in MM.