MIT Technology Review has an article about the quest to show that biological sex matters in the immune system. It centers around the work of Sabra Klein, a Professor of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health. Both the biological and behavioral difference between the sexes are important. For example—

Despite a historical practice of “bikini medicine”—the notion that there are no major differences between the sexes outside the parts that fit under a bikini—we now know that whether you’re looking at your metabolism, heart, or immune system, both biological sex differences and sociocultural gender differences exist. And they both play a role in susceptibility to diseases. For instance, men’s greater propensity to tuberculosis—they are almost twice as likely to get it as women—may be attributed partly to differences in their immune responses and partly to the fact that men are more likely to smoke and to work in mining or construction jobs that expose them to toxic substances, which can impair the lungs’ immune defenses.

How to tease apart the effects of sex and gender? That’s where animal models come in. “Gender is a social construct that we associate with humans, so animals do not have a gender,” says Chyren Hunter, associate director for basic and translational research at the US National Institutes of Health Office of Research on Women’s Health. Seeing the same effect in both animal models and humans is a good starting point for finding out whether an immune response is modulated by sex.
But you can’t find sex differences if you’re only studying one sex. Klein remembers a meeting where a researcher on nematodes, a type of parasitic worm, mentioned that his experiments were done only in male mice, because female mice didn’t get infected. She recalls being flabbergasted that he never thought to study why the nematodes couldn’t infect the females. “Oh my God, you might have a cure for these nematodes that wreak havoc!” she recalls thinking.

BTW, given the politics of many of the likely readers, the article wisely provides this definition—

When referring to people in this article, “male” is used as a shorthand for people with XY chromosomes, a penis, and testicles, and who go through a testosterone-dominated puberty, and “female” is used as a shorthand for people with XX chromosomes and a vulva, and who go through an estrogen-dominated puberty.

Well, at least MIT may have a reasonable working definition for woman.

Read the whole thing.