Production of sIL-2Rα in FL patients. (A) mRNA levels of IL-2Rα measured by quantitative RT-PCR. CD3⁺ T cells, CD19⁺ B cells, or CD14⁺ monocytes were isolated from biopsy specimens of FL (n = 12) or peripheral blood of normal individuals (n = 5). mRNA levels were normalized to GAPDH. (B) A representative sample (n = 15) showing surface expression of IL-2Rα on CD4⁺ T cells from FL (left) and benign lymph node (right). (C) Summary of the numbers of IL-2Rα–expressing cells in subsets of CD4⁺ T cells, CD19⁺ B cells, or CD14⁺ monocytes from FL (n = 10) and benign lymph nodes (n = 5). (D) A graph showing sIL-2Rα levels measured by ELISA in culture supernatants of cell lines treated with or without PMA/Ion. (E) Surface expression of IL-2Rα by flow cytometry on Karpas299 cells treated with or without PMA/Ion. (F) A graph showing sIL-2Rα levels measured by ELISA in culture supernatants of resting and activated CD4⁺ T cells from 2 patient samples.