Serum level of soluble interleukin-2 receptor correlates with CD25 expression in patients with T lymphoblastic lymphoma.

Acute lymphoblastic leukaemia/lymphoma (ALL/LBL) is an aggressive form of non-Hodgkin's lymphoma (NHL) affecting B-cells or T-cells, respectively. The serum level of soluble interleukin-2 receptor (sIL-2R) is known to reflect the immune activity and tumour volume in aggressive NHL; however, the release of sIL-2R in LBL has not been extensively studied. Further, the relationship between sIL-2R release and the expression level of IL-2R α subunit (CD25) remains unknown. In the present study, we examined the serum level of sIL-2R in 23 patients with T lymphoblactic lymphoma (T-LBL) and compared these with the levels in 20 patient with T acute lymphoblastic leukaemia (T-ALL), 40 patients with diffuse large B-cell lymphoma (DLBCL) and 40 patients with peripheral T-cell lymphoma (PTCL), not otherwise specified. The release of sIL-2R into the serum in patients with T-LBL was significantly lower than that for T-ALL, DLBCL and PTCL (p<0.001). Immunohistochemistry revealed that CD25 expression was correlated with the serum level of sIL-2R in T-LBL (p=0.0069), whereas no correlation was found to exist between serum sIL-2R levels and CD25 expression in patients with DLBCL (p=0.348) and PTCL (p=0.266). Furthermore, double immunohistochemical analysis revealed that CD25-positive cells were also found to be Foxp3-positive non-neoplastic T-cells. In conclusion, CD25-positive non-neoplastic T-cells in T-LBL are presumed to be the primary source of sIL-2R, and the low number of cells present results in a lower level of sIL-2R released into the serum compared with the other aggressive and highly aggressive lymphomas.