X’d-Out: X Chromosome Tied to Sex-Based Immune Differences

A greater susceptibility to autoimmune conditions in women could be tied to how X chromosome inactivation works, according to illuminating work on T cells led by Montserrat Anguera, PhD, of Penn Vet, and Nikhil Jiwrajka, MD, of Rheumatology. Generally, mammal cells use just one X chromosome at a time, which isn’t an issue for males, who only have one X-chromosome. But female mammals randomly inactivate one of their two X chromosomes in each cell, a process that is fairly dynamic in T cells, where defects could affect immune responses.