Which of the following would supress the immune system?

high level of cortisol
creation of Th cells
increased secretion of thymosins
activation of complement
interferon release

high level of cortisol

Out of the options provided, the factor that would suppress the immune system is a high level of cortisol. Cortisol is a hormone released by the adrenal glands in response to stress. While it has important functions in the body, prolonged high levels of cortisol can suppress immune system activity, making the body more susceptible to infections and diseases.