Soluble interleukin-2 receptor levels in patients with undifferentiated and lymphoblastic lymphomas: correlation with survival.

We have been able to detect soluble interleukin-2 receptors (IL-2R) in pretreatment sera from 80 patients with undifferentiated lymphoma (predominantly Burkitt's lymphoma) and lymphoblastic lymphoma. The demonstration of IL-2R in lymphoma-derived cell lines by immunoprecipitation and direct staining indicates that IL-2R is synthesized by the tumor cells. Comparisons were made with two other subject groups: 42 sarcoma patients and 17 normal individuals. The distribution of soluble IL-2R values for lymphoma patients (geometric mean, 1,132 U/mL) was significantly greater than that of sarcoma patients (geometric mean, 332 U/mL; P = .0001) or normal individuals (geometric mean, 238 U/mL; P = .0001). Patients with undifferentiated lymphoma stages B, C, and D had significantly higher soluble IL-2R values (geometric mean, 1,648 U/mL) than stages A and AR (geometric mean, 706 U/mL; P = .0001) or lymphoblastic lymphoma (geometric mean, 826 U/mL; P = .0002). Within the lymphoma group, the soluble IL-2R level was found to be the most significant prognostic indicator of disease-free interval and survival when compared with other previously recognized factors such as histology, stage, bone marrow involvement at presentation, lactic dehydrogenase (LDH), uric acid (UA), and age. No factor was significantly associated with response to therapy, ie, the initial achievement of complete remission (CR) status, although small numbers of patients with a partial response limit interpretation. Soluble IL-2R levels were measured serially in two patients and were found to be elevated at presentation or relapse and to decrease to normal levels during periods of disease remission. IL-2R appears to reflect tumor burden and may prove to be a useful and specific marker for lymphoid tumors.