The discovery of plasma cells: An historical note.

The name plasma cell was introduced by the anatomist Heinrich H. von Hartz-Waldeyer in 1875. Plasma cells derive from small B lymphocytes after their activation. A fully mature plasma cell lacks surface immunoglobulin expression. Its form is round or oval, with characteristic basophilic cytoplasm and an eccentric nucleus that contains coarse heterochromatin. Antigen activation of mature B cells leads initially to germinal center development, the transient generation of plasmablasts that secrete antibody while still dividing, and short-lived extrafollicular plasma cells that secrete antigen-specific germ line-encoded antibodies. Plasma cells are characterized by the co-expression of CD138 and CD38, which allows their identification in flow cytometry in bone marrow, peripheral blood, or cell suspensions from tissues. The identification of plasma cells as antibody producers was a key discovery that paved the way for the development of monoclonal antibodies.