Cytokine production and aging: overproduction of IL-8 in elderly males in response to lipopolysaccharide

Interleukin-8 (IL-8) is a chemoattractant cytokine for polymorphonuclear neutrophils, and is found at the site of inflammation and infection. The levels of IL-8 from an elderly (ages 65-79) and young (ages 20-27) population were compared. Secretion of IL-8 was measured in monocyte conditioned medium (MCM), under both a spontaneous condition and with stimulation with detoxified LPS (10 mg/ml). Spontaneous production of IL-8 in the elderly group (39.4 ± 8.3 ng/ml, n = 16) was found to be significantly lower than the control group (66.4 ± 5.0 ng/ml, n = 17), P < 0.01. A sex difference was observed within the elderly population, with the male elderly producing 8.8 ± 2.1 ng/ml of IL-8 and the elderly females producing levels of 57.8 ± 9.1 ng/ml. There was a good correlation between IL-8 and IL-1 production in the elderly but differences between the elderly and young production of IL-1 did not reach statistical significance. IL-8 and TNF production did not correlate. Upon stimulation with the LPS, the male elderly levels increased eightfold (70.1 ± 11.8 ng/ml) and was significantly different from the young male level, P < 0.01, while the female elderly showed no change with stimulation. No sex difference was observed in the control population. These results indicate that the spontaneous secretion of IL-8 in elderly males is lower than that of both elderly females and the young control group. However, upon stimulation with LPS, the elderly males are capable of an overproduction of IL-8 when compared to the young group and the elderly females. This overproduction may be the result of an in vivo priming in this healthy elderly group. The female elderly followed a pattern similar to the young group, showing no change upon stimulation with the detoxified LPS. Sex differences related to the immune.