SYNDECAN-1 EXPRESSION ON MALIGNANT-CELLS FROM THE BLOOD AND MARROW OFPATIENTS WITH PLASMA-CELL PROLIFERATIVE DISORDERS AND B-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA

Syndecan-1 is a low-affinity receptor for basic fibroblast growth fact or (bFGF). In this study, we used flow cytometry to examine expression of syndecan-1 on monoclonal cells from the blood (n = 37) and marrow (n = 81) of patients with plasma cell (PC) proliferative disorders (PC PD) and blood cells from patients (n = 39) with B cell chronic lymphoc ytic leukemia (B-CLL). The marrow CD38(+)CD45(-) and CD38(+)CD45(+) PC were syndecan-1 positive in all patients with PCPD and there was no d ifference between patients with monoclonal gammopathy of undetermined significance (MGUS) vs multiple myeloma or cases with vs without bone lesions, In 38% of cases, syndecan-1 expression on the PC was heteroge neous with greater than or equal to 25% of PC syndecan-1 negative. We found similar syndecan-1 expression on blood and marrow PC in the 36 c ases with paired samples. CLL cells were syndecan-1 negative in 97% (3 8/39:) of the cases. Syndecan-1 is a useful marker to detect malignant plasma cells in the blood or marrow; however, it is not helpful in di stinguishing MGUS from active myeloma. In addition, syndecan-1 is pres ent on the less mature (CD45(+)) PC, and there is heterogeneity of exp ression within and between patients. The relevance of the bFGF bound t o myeloma cells via syndecan-1 remains to be elucidated.