Increased Serum Concentration of the Soluble Interleukin-2 Receptor in Cutaneous T-Cell Lymphoma

BACKGROUND AND DESIGN: The serum concentration of soluble alpha-chain receptor for interleukin-2 (sIL-2R) was determined in 101 patients with cutaneous T-cell lymphoma (CTCL). RESULTS: The serum concentration of sIL-2R correlates positively with CTCL tumor burden as determined by several clinical parameters (ie, clinical subtype of disease, extent of skin involvement, T rating, and stage), by serum lactate dehydrogenase concentration, and by Sézary cell counts in erythrodermic disease. The median value of sIL-2R in erythrodermic CTCL was more than threefold higher than that of classic mycosis fungoides (MF). The proportion of patients with elevated sIL-2R concentration (> 1000 U/mL) also increased in CTCL in a similar fashion according to the clinical type of disease (MF patch phase, 15%; MF plaque phase, 33%; MF tumor phase, 47%; and erythrodermic variants, 90%). However, no correlation was found between sIL-2R serum concentration and expression of membrane-bound IL-2R alpha chain (CD25) on lymphoid cells in skin lesions and peripheral blood. Significantly, multivariate analysis of various prognostic factors demonstrated that in erythrodermic CTCL, sIL-2R serum concentration correlated best with survival and was a better predictor of prognosis than stage, Sézary cell counts, or lactate dehydrogenase values. CONCLUSIONS: These findings document the usefulness of the measurement of the sIL-2R serum concentration to determine tumor burden and prognosis in patients with CTCL.