Abstract
LITTLE is known about the pathogenesis of the benign monoclonal gammopathies or the neoplasms of the immunoglobulin-producing cells (multiple myeloma and malignant Waldenström's macroglobulinemia). There is some basis, however, for suggesting that these abnormal cells might be derived from cells once involved in immune responses. In the normal development of immunocytes, each cell becomes differentiated to synthesize and secrete only one molecular species of immunoglobulin. In a normal response to antigen, a number of different specialized cells are "selected" by antigen and stimulated to divide and form small clones. In certain exaggerated cellular immune responses, the number of cells producing . . .