title: Mott cells in a patient with a lymphoproliferative disorder. Differentiation of a clone of B lymphocytes into Mott cells.
abstract: An unusual lymphoproliferative disorder characterized by diffuse infiltration of the bone marrow by lymphocytes and Mott cells without other organ involvement is described. The clinical course was remarkable for a spontaneous remission. The cells infiltrating the bone marrow were predominantly lymphocytes and Mott cells. The lymphocytes stained exclusively for membrane IgM-kappa by immunofluorescence, and the Mott cells contained typical Russell bodies staining in a rim pattern for IgM-kappa. These findings suggested that the lymphocytes were differentiating into Mott cells. This was demonstrated in vitro by stimulating peripheral blood lymphocytes with mitogens. Differentiation of B lymphocytes into Mott cells containing IgM-kappa was observed. These appeared to be identical to the Mott cells found in the marrow. The Mott cells were probably nonsecretory because of the absence of a monoclonal serum immunoglobulin. Electron microscopic studies showed that the electron-dense cytoplasmic inclusions resembled Russell bodies. This case probably represents an expanded clone of B lymphocytes with demonstrable in vivo and in vitro differentiation into Mott cells.
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal / Q000032:analysis; D001402:B-Lymphocytes / Q000648:ultrastructure*; D002454:Cell Differentiation; D002999:Clone Cells; D003937:Diagnosis, Differential; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D066298:In Vitro Techniques; D008232:Lymphoproliferative Disorders / Q000276:immunology / Q000473:pathology*; D010641:Phenotype; D010950:Plasma Cells / Q000648:ultrastructure*
chemical_list: D000911:Antibodies, Monoclonal