$910,000: NIH Studied How Gender-Affirming Hormone Therapy Affects the Immune System. Terminated.

Sex hormones have well-documented effects on immune function — this is basic immunology, not contested science. Estrogen generally enhances immune responses (which is why women have higher rates of autoimmune conditions); testosterone tends to suppress them. NIH funded $910,000 in research examining how gender-affirming hormone therapy — which involves exogenous sex hormones at non-physiological concentrations — affects immune function in transgender individuals. This has direct clinical relevance for understanding autoimmune risk, vaccine responses, and susceptibility to infectious disease in this population.

At $910,000, this is one of the smaller NIH grants in the DOGE transgender research list. It was terminated under EO 14168 along with larger grants. The sex-hormone-immune-function research area is itself well-established in mainstream immunology; the transgender patient population was the novel element that connected it to the executive order.