Soluble interleukin-2 receptors in sera of children with primary malignant neoplasms

T lymphocyte activation regulates the autocrine type secretion of interleukin-2, a T cell growth factor and the de novo expression of its cell-surface receptor (IL-2R). Afterwards, a special, truncated form of the IL-2R is secreted into the serum as a soluble molecule. Soluble interleukin-2 receptor (sIL-2R) in serum is non-specific marker of common activation of the cellular immune regulation. This study reports the results of an early diagnostic observation of sIL-2R level in the sera of 18 primary solid pediatric malignancies.

18 children between the ages of 1 and 12 represented the Study Group of solid tumor bearing patients. 12 healthy children between the ages of 1 and 12 represented the Control Group. Concentrations of sIL-2R were detected in the sera of the children employing a double-antibody sandwich enzyme-linked immunosorbent assay (T Cell Sciences).

Control Group concentrations of sIL-2R were in the range of 101.9 to 255.3 IU/mL with a mean value of 178.6 IU/mL. Serum levels of sIL-2R were markedly elevated in the sera of children with solid tumors (Study Group) to levels between 223.8 IU/mL and 927 IU/mL with a mean value of 575.4 IU/mL.

1) The shedding of cell-surface receptors of immunological effector cells is a common physiological mechanism; 2) Presence of sIL-2R represents a sign of an overall activation of the effector elements of the host's cellular immune system; 3) An increase in the levels of sIL-2R represents an active phase of progression; conversely, decreasing levels indicate tumor regression; 4) Serum levels of sIL-2Rs may represent a useful laboratory parameter in choosing an efficient anti-cancer therapy. Thus, the level of sIL-2R in childhood solid tumor patients has a prognostic significance.