The immune system is like an orchestra, where B cells produce antibodies and sex chromosomes and sex glands (ovaries or testes) conduct their performance. Until now it was unclear which of the two had the upper hand: the genes in the chromosomes or the hormones from the glands. Now scientists have managed to separate these two influences.
To do this, they used mice with different combinations: XX or XY chromosomes could be paired with ovaries or testes. In the brains of healthy mice, the strongest inflammation turned up in those whose XY chromosomes were paired with ovaries. So what matters is not each factor on its own, but their combination.
This finding suggests that Alzheimer's drugs may need to be chosen with a patient's particular combination of chromosomes and glands in mind. Every immune orchestra plays its own melody, and now we can hear its notes more clearly.
Mice with the combination of XY chromosomes and ovaries (a rare pairing made possible by the genetic model) had the highest levels of IgG and IgM in the brain, pointing to strong inflammation.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.