Abstract
Summary. Lymphopenia and monocytosis were found in one third of untreated myeloma patients but there was no correlation between the two. Half of the patients studied had an increase in medium basophilic lymphoid cells, and eight had a raised PAS score. Lymphocytes from the majority of untreated myeloma patients failed to respond to antigenic stimulation in vitro compared with age matched controls. Three patients were immunized but showed no increase in immunoblasts or rise in antibody titre. The findings strongly suggest that abnormal lymphocytes are present in the blood in myeloma. The failure of lymphocytes to respond to antigen provides an explanation for the lack of normal plasma cells and depressed antibody responses in myeloma.