B-cell; Flow Cytometry; Gammopathy; Monoclonal; Multiple; Myeloma; Plasma Cell

Background Multiple myeloma (MM) is characterized by accumulation of pathological plasma cells (PCs) in bone marrow (BM) as a result of deregulation of B-cell development. To clarify its pathophysiology it is necessary to investigate in detail the developmental stages of B-cells. Materials and Methods Enumeration of total CD19-positive (CD19+) cells and their subpopulations together with PCs was done in peripheral blood (PB) and BM of newly diagnosed monoclonal gammopathy patients and control subjects. Representation of subsets was compared among groups and relationships between subset percentage and cytogenetic/biochemical findings were analyzed. Results A lower number of total CD19+ cells was found in MM, particularly in advanced stages of disease.