The human immune system is adaptive, remembering past infections and training itself to guard against future similar infections. But what happens when people have compromised immune systems due to chronic conditions, aging, or medications that decrease immunity as a side effect? In such cases, people can get opportunistic infections, so called because the germs causing illness would have been eradicated by a fully healthy immune system. Conditions and medicines causing immune suppression are on the rise, and so are patients experiencing opportunistic infection. Now, researchers have uncovered a sex-based variance in the trained immune memory response to infection in mice that might translate to humans.
