Release of beta 2-microglobulin by human tumors grown in nude mice

Human tumors implanted subcutaneously into athymic mice produced human beta 2-microglobulin which was readily identified and quantified in mouse plasma. Implanted solid tumors of the lines Clouser, SW480, Hep-2, Capan-1, and HT-29 released amounts of beta 2-microglobulin directly related to tumor mass. The extractable beta 2-microglobulin per gram of tumor was constant for each cell line, but there was a 100-fold variation between the lines. In general, the plasma level of beta 2-microglobulin correlated with the amount of free beta 2-microglobulin extracted from each tumor. From these observations it can be concluded that the variablility observed in the circulating levels of beta 2-microglobulin among cancer patients is related to the beta 2-microglobulin content of the tumor and the total tumor mass.