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The object of the study was to determine whether male and female sex steroids produce divergent effects on Th1 and Th2 cytokine release following trauma-haemorrhage. Recent studies indicate that androgens are responsible for the depressed splenocyte Th1 cytokine release in males following trauma-haemorrhage. In contrast, female mice maintain their Th1 cytokine release capacity following trauma-haemorrhage. Nonetheless, the effect of male and female sex steroids on Th1 and Th2 cytokine release following trauma-haemorrhage remains unknown. Male C3H/HeN mice were castrated and treated with pellets containing either vehicle, 5alpha-dihydrotestosterone (DHT), 17beta-estradiol (estradiol), or a combination of both steroid hormones, for 14 days prior to soft-tissue trauma (i.e. laparotomy) and haemorrhagic shock (35+/-5 mmHg for 90 min followed by adequate fluid resuscitation) or sham operation. Untreated male and female mice, as well as DHT treated female mice, served as control groups. Twenty-four hours later the animals were sacrificed, plasma obtained and splenocytes harvested. Plasma DHT and estradiol levels in treated animals were comparable with intact male and female mice, respectively. A significant depression of splenocyte Th1 cytokines, i.e. IL-2, IFN-gamma, was observed in DHT treated castrated animals, DHT treated females, and untreated males following trauma-haemorrhage, as opposed to maintained Th1 cytokine release in estradiol treated and estradiol/DHT treated castrated animals and females. The release of the anti-inflammatory cytokine IL-10 was markedly increased in DHT treated mice and males subjected to trauma-haemorrhage compared to shams, but decreased in estrogen treated mice and females under such conditions. These results suggest that male and female sex steroids differentially affect the release of Th1 and Th2 cytokines following trauma-haemorrhage and should be further studied for their potential to modulate splenocyte function in trauma victims., (Copyright 2001 Academic Press.)

Studies have shown gender dimorphism in cell-mediated immune responses following haemorrhage, with depressed responses in young males and maintained or enhanced responses in proestrus females. However, it remains unknown whether or not the sexually dimorphic immune response to haemorrhage provides any protection against a subsequent in vivo polymicrobial septic challenge. To study this, male and proestrus female C3H/HeN mice were subjected to haemorrhage (35+/-5 mmHg for 90 min followed by fluid resuscitation) or sham operation. Twenty-four hours thereafter, all mice were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP) and survival was assessed over a 10 day period. Haemorrhage prior to CLP significantly increased mortality in males as compared to shams. In contrast, mortality in females following CLP was comparable between the sham and haemorrhage groups. Plasma levels of interleukin (IL-)6, tumour necrosis factor (TNF)-alpha and prostaglandin E(2)(PGE(2)) at 5 h after CLP were significantly increased in males subjected to prior haemorrhage. In contrast, plasma levels of IL-6 and TNF-alpha in females did not increase under such conditions. PGE(2)levels were comparable in males and females following CLP, however prior haemorrhage significantly reduced PGE(2)levels in females, whereas no change was observed in males. Liver and splenic expression of cyclooxygenase-2 protein paralleled the changes in plasma PGE(2). Female sex hormones, therefore, appear to play an important role not only in maintaining immune function following haemorrhage, but also provide a survival advantage against subsequent septic challenge., (Copyright 2001 Academic Press.)