SUN-309 Interleukin-2 Administration in Healthy Men Activates Cortisol Secretion in an Age-, Dose-, and Body Composition-Dependent Way

Context. Interleukin-2 (IL2), a proinflammatory cytokine, is used for treatment of malignancies. Increased cortisol and ACTH were noted, but not investigated in detail. This is the first study in healthy men which uses moderate high IL2 doses as used in cancer treatment. Objective. The goal of this study was to quantify cortisol secretion after a single sc injection of IL2 at 1900 h in young and older healthy men in relation to dose, age and body composition. Design. This was a placebo-controlled, blinded, prospectively randomized cross-over study in 17 young subjects (mean age 24.1 yr, range 19–30 yr) and 18 older subjects (mean age 63.9 yr, range 60–75 yr). The subjects underwent 24 h of blood sampling at 10-min intervals, starting at 1800 h. At 2000 h IL2 (3 or 6 million units per m(2) body surface) or saline was injected sc. Lights were off between 2300 and 0700 h. Setting. The study was performed in a Clinical Translational Research Unit. Outcome measures. Mean concentrations of cortisol, deconvolution analysis, and approximate entropy. Abdominal visceral fat (AVF) and total abdominal fat (TAF) were calculated from single slice CT. Results. Cortisol concentrations started to rise at 2300 h. The AUC’s during the lights-on periods were unchanged by IL2. Therefore, most analyses were restricted to the 8 h lights-off period. In young volunteers pulsatile cortisol secretion increased from 52.9±5.8 to 77.0±8.0 µg/L/8h and in older subjects from 60.6±3.8 to 70.6±4.6 µg/L/8h (GLM: treatment P <0.0001, treatment x age: P=0.02, mean ± SEM). Thus, the effect was smaller in older subjects. Increasing the IL2 dose increased cortisol secretion in young subjects (P= 0.001), but not in older subjects (P=0.90). In addition, the slopes (mean ± SE) of the linear part of the concentration curves after IL-2 were steeper than after placebo, pointing to accelerated release (young 1.40±0.13 to 3.76±0.11, P<0.0001, in older 1.27±0.04 to 3.28±0.15, P<0.0001).The incremental nocturnal pulsatile cortisol secretion after IL2 was negatively related to body composition (AVF: R= – 0.41, P=0.019; TAF R= – 0.41, P=0.043). Nocturnal ApEn-cortisol did not increase after low dose IL2 (0.981± 0.099 to 0.991±0.046, P=0.92). After high-dose, ApEn increased from 0.877±0.041 to 1.024±0.049, P=0.008, not correlated with body composition, nor with age. The ApEn increase points to decreased secretory regularity imposed by enhanced CRF signaling, rather than diminished cortisol feedback, which leads to greater secretory regularity. Conclusion. Il2, a paradigm for inflammation, increased pulsatile cortisol secretion, more in young than in older subjects. Higher IL2 doses in young subjects amplified cortisol secretion, but not in older subjects. Cortisol secretion exhibited an advance (earlier) time shift, accompanied by accelerated secretion. Incremental nocturnal cortisol secretion was negatively related to fat mass.