Investigation of interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R) and soluble gp130 (sgp130) in sera of cancer patients.

The serum levels of interleukin-6 (IL-6), sIL-6R and sgp130 were investigated in 76 cancer patients in comparison with 28 healthy controls. IL-6 is a multifunctional cytokine involved in certain malignant diseases. Soluble IL-6 receptor as agonist enhances the biological effect of released IL-6. Soluble gp130 as antagonist inhibits the effect of the IL-6/sIL-6R complex. Patients with different types of tumour (breast/gastrointestinal/uterine/ovarian/renal/bladder) were divided into four groups according to tumour stage and previous therapy (stage I + II without or after chemo-/radiotherapy, stage III + IV without or after chemo-/radiotherapy). The distribution of different tumour histotypes was similar in each group of patients. The levels of the three serum parameters were determined by ELISA. At each tumour stage either without or after chemo-/radiotherapy, the serum values of IL-6 were found to be not significantly different from those of controls. The values of sIL-6R were significantly elevated in stage I + II (P < 0.02) patients, with a borderline significance in stage III + IV (P = 0.06), in both cases only when no additional therapy was initiated. The serum values of sgp130 increased significantly at each tumour stage both without and after chemo-/radiotherapy (P < 0.001). A significant correlation was found between the values of sIL-6R and sgp130 in stage I + II (P < 0.02) and III + IV (P < 0.004) patients, in both cases without chemo-/radiotherapy. There were no other significant correlations. In conclusion, the simultaneous measurement of IL-6, sIL-6R and sgp130 in sera is an important factor in evaluating the biological effect of IL-6 in malignant disease. This is the first report to investigate sgp130 in cancer patients with different types of tumour.