GammaG-globulin production and light-chain metabolism in patients with metastatic cancer.

GammaG-Globulin and excess light-chain metabolism were studied in eight subjects with progressive metastatic malignant disease by determining the plasma radioactivity curves following the administration of appropriately labeled substances. In addition to the plasma die-away curves, which required about 3 weeks for full expression for gamma-globulin, but only 3 to 4 days for light-chain, urinary excretion of the label from metabolized protein was determined. The data are compared to similar studies in control individuals. The metabolism of excess light chain was similar to normal in all respects. The total synthesis of gammaG-globulin was increased with a mean value about twice normal. The mean survival time of a circulating immunoglobulin molecule was short, indicating rapid loss from the system. Other aspects of immunoglobulin metabolism were similar to normal with a normal percentage of the labeled protein appearing in the urine, suggesting no abnormality in the utilization pattern but simply an increased rate of turnover. The capability of malnourished patients with cancer to produce large quantities of immunoglobulin is not specific for this disease, since similar patterns may be seen in response to infections in protein-depleted individuals. However, there is the possibility that the cancer itself acts as an inciting agent in these subjects. Furthermore, such sustained protein synthesis may place an additional burden on already compromised host metabolism.