Peripheral Blood Lymphocyte Subpopulations in Multiple Myeloma

Abstract

Human myeloma is regarded as a monoclonal malignancy of B-type secretory lymphoid cells and has been classified as plasmocytic immunocytoma by Lennert et al. (1). Plasma cells carrying the morphological appearance of tumor cells can be identified in the bone marrow of these patients (2,5,6). Myeloma cells disseminate to multiple skeletal sites and may spread to other organs, but malignant plasma cells are only rarely demonstrable in peripheral blood as judged by light microscopy (3). The idiotypic determinant (I.D.) of the myeloma protein, which is also carried by the surfaceimmunoglobulin (SmIg) of the myeloma cell clone, represents an individual and tumor-specific antigenic determinant (2,5). Previous investigations using FITC-labelled heterologous anti-idiotypic antisera (AIAS) have shown that a varying percentage of peripheral blood lymphocytes (PBL) bear the I.D. of the patient’s myeloma protein, proving that they must also belong to the individual tumor cell clone (2,4,5). The percentage of PBL detected by AIAS closely parallels the clinical course of multiple myeloma (2,7).