Dynamic Changes in Soluble Interleukin-2 Receptor Levels after Lung or Heart-Lung Transplantation

Abstract

Activation of T-lymphocytes is accompanied by the release of interleukin-2 receptors (IL-2R) in a soluble form that can be measured as an index of the activation process. We performed a prospective, blinded study of the dynamic changes in soluble IL-2R levels in serum in 12 patients undergoing lung or heart-lung transplantation. The levels of soluble IL-2R were markedly elevated during episodes of rejection (geometric mean value .times./.div. SEM = 3,770 .times./.div. 1.06 versus 411 .times./.div. 1.08 U/ml for normal controls, p < 0.0001). Levels of soluble IL-2R were 2,105 .times./.div. 1.16 U/ml with rejection episodes in single lung recipients verus 5,500 .times./.div. 1.30 in recipients of two lungs (p = 0.005). Soluble IL-2R levels were 1,468 .times./.div. 1.05 during episodes of nonbacterial infections, 1,879 .times./.div. 1.34 with bacterial infections, and 5,056 .times./.div. 1.08 with sepsis (p < 0.001 for each category compared to normals). Levels of soluble IL-2R exceeded 6,750 U/ml only with rejection episodes and were greater than 4,100 U/ml either with rejection, clinical sepsis, or overwhelming bacterial infection. We conclude that marked elevations of soluble Il-2R are associated with rejection, intermediate elevations with either rejection or infection, and that low levels of soluble Il-2R exclude rejection.