Plasma cells were clearly identified by high fluorescent intensity staining with CD38 (CD38⁺⁺).

(A,B) Cytoplasmic staining with anti-kappa and anti-lambda monoclonal antibodies demonstrated light-chain restriction. (C) Not all CD138⁺ cells were CD38⁺⁺. (D-F) CD45 expression subdivided plasma cells into primitive (CD45⁺⁺), immature (CD45⁺), and mature (CD45⁻) subpopulations. (E) Predominantly CD45⁻ plasma cells. (F) Predominantly CD45⁺ plasma cells.