We have developed a simple, sensitive, specific and reproducible technique for quantitating the newly synthesized tumor secreted M component biomarkers using in vivo radiolabeling with 6-14C-arginine. With this technique, we are able to detect as few as 1 x 10 to the 6th power plasma cells in the mouse and we can repeatedly measure the total body burden of malignant plasma cells in the murine plasmacytoma system (LPC-1 in BALB/c mice) and multiple myeloma in man. Further study of the mouse model is needed in order to identify and understand the interrelationship of tumor cell and host factors and the effect on these factors of various modes of treatment (chemo-, radio- and immunotherapy) that may modify M component synthesis. We also plan to study the mouse plasmacytoma system as a model for autologous bone marrow transplantation with the objective of developing a more aggressive approach to the therapy of this disorder in man. These studies are designed to complement similar studies in man and to permit the development of concepts and techniques which will be applied in the parallel human studies. Body burden measurements in man will be correlated with other parameters of the extent of the disease, the effect of therapy, survival and remission/response duration. A better understanding of the interrelationship between tumor cell and host factors as probed by 6-14C-arginine pulse labeling technique will help in improved assessment of the nature and extent of the disease and in development of new approaches to therapy.