THROMBOXANE PRODUCTION IN THE BLOOD OF WOMEN INCREASES AFTER MENOPAUSE WHEREAS TUMOR-NECROSIS-FACTOR IS REDUCED IN WOMEN COMPARED WITH MEN

Previously we have shown that incubation of heparinized blood with a l ow dose of lipopolysaccharides (5 ng/ml) resulted in a 60% higher gene ration of TxB2 in the blood of young men as compared with that of youn g women. In the present study, we investigated a group consisting of 3 8 healthy men and 38 healthy postmenopausal women aged 50-73 years wit h no drug use and no known chronic disease. In contrast to our earlier observation that young men produce more TxB2 than young women, no sig nificant difference was observed between the men and women when all th e participants above 50 years of age were included (5.7 +/- 0.6 ng/l f or men versus 5.2 +/- 0.7 ng/l for women). However, a strong correlati on was found with simple regression analysis when increasing TxB, gene ration was compared with years after menopause (P < 0.0001). No such c orrelation was observed for increasing age of men and their TxB2 produ ction. The LPS stimulation system of whole blood was also used to eval uate the production of tumor necrosis factor (TNF-alpha) in older peop le. Men were found to generate 60% more TNF-alpha than women, but no c orrelation was found between increasing age of women and TNF-alpha pro duction as observed with TxB2. Risk factors such as SDS-cholesterol, f ibrinogen and factor VII were the same in men and women, whereas total cholesterol was higher in women than in men (P < 0.05). Since TxA2 is known to be a mediator of atherosclerotic-induced lesions and TNF-alp ha is a well-established indicator of inflammatory reactions, we propo se that the reduced production of TxB2 and TNF-alpha in women in our m odel system may partially explain the lower incidence of atheroscleros is in women as compared with men, and the phenomenon of increased inci dence of this disease after menopause.