IDENTIFICATION OF EARLY PLASMA-CELLS IN PERIPHERAL-BLOOD AND THEIR CLINICAL-SIGNIFICANCE

In the peripheral blood (PB) we detected so-called early plasma cells that might already be committed to entering the bone marrow (BM). By t wo-colour staining with FITC-anti-CD38 antibody, their intensity (CD38 (++)) of expression of CD38 antigen was between that of germinal centr e (GC) B cells (low expression (CD38(+))) and that of BM plasma cells (high expression (CD38(+++))), and their phenotype was CD38(++) CD19() CD10(-) CD20(-) CD21(+) CD24(-) CD39(+) CD5(-) VLA-4(+) VLA-5(-) MPC -1(-) without expression of surface membrane IgM (SmIgM). Morphologica l and immunological examination of the sorted cells confirmed that the y were plasmacytoid cells with expression of cytoplasmic IgG (cIgG). V ariations of these early plasma cells were examined in various disease s. In active systemic lupus erythematosus, bacterial septicaemia and l iver cirrhosis, early plasma cell levels were significantly increased in PB, and after subsidence of such inflammation (inactive states) the se cells returned to normal levels. In contrast, normal early plasma c ells were significantly suppressed in myelomas, whilst normal or sligh tly increased numbers of early plasma cells was found in benign monocl onal gammopathy (BMG). In addition, the number of normal early plasma cells returned to a normal level in myeloma cases with complete respon ses, Therefore, early plasma cells were identified phenotypically, and an increase and decrease in these cells in PB may reflect mobilizatio n and suppression, respectively, of activated B cells into RM plasma c ells.