Multiple myeloma: an immunologic profile. I. Peripheral blood studies.

Seventy-four patients with multiple myeloma, 17 untreated and 57 treated, were studied to characterize their peripheral blood lymphocytes. PBL were studied for E, EAC, and EA rosette-forming cells, SIg, and Fc receptor-bearing cells. The responses to HA, Con A, and PWM were assessed as well as their ability to stimulate or to respond in a MLC. Finally, the capacity of mitogen-stimulated lymphocytes to lyse Chang cells, CRBC, and PHA-stimulated lymphoblasts was examined. These results were compared with a group of normals and patients with benign monoclonal gammopathy. In untreated myeloma patients there was a normal percentage of T cells, but an abnormal distribution of B cells as judged by a decrease in SIg-bearing cells, as well as an increase in EAC rosette-forming cells. Subpopulation analysis showed a marked increase in EAC rosette-forming cells without SIg. PHA, Con A, and PWM, and response in MLC were all normal. However, the ability to stimulate in MLC was significantly depressed. Treated myeloma patients had similar findings, except that the response to PWM was significantly depressed. The capacity of PWM-stimulated cells to lyse target cells was depressed in both groups. The results indicate that, in the peripheral blood of myeloma patients, there are populations of lymphocytes characterized by the presence of the EAC receptor without SIg, which are deficient in the capacity to stimulate an MLC response and the ability to be cytotoxic when stimulated by PWM. The results form a baseline for the study of abnormal lymphoid function in human myeloma.