Sex differences in infection and sepsis.

Sex and gender-based differences in responses to infection and sepsis are evident. Estrogens increase immune function, sometimes to the point of inducing autoimmune disease. Testosterone suppresses immune function, sometimes leading to a worsened outcome following traumatic injury. Therapies using sex hormones to improve outcomes after sepsis and hemorrhagic shock and to reduce exacerbations of autoimmune diseases are being studied. Differences in sex hormone levels may not tell the whole story. Studies of immune function in girls and boys before puberty may be helpful. Differences found early might indicate that factors other than estrogen and androgen levels are contributing. Variations in societal role acculturation and exposures that are gender based also may be involved. Clinicians must consider sex and gender when attempting to determine the risk of infection, sepsis, and immune dysfunction in populations. Clinical applications of sex and gender differences are just beginning to occur with the genesis of sex hormone-based treatments. The large-scale efficacy of such treatments has yet to be reported. Innovative strategies based on sex or gender differences in immune responses may soon be available and may lead to essential data for clinical decision making. The impact of sex and gender differences on long-term health outcomes remains to be seen.