Hemophagocytic lymphohistiocytosis (HLH) is an inherited disease of the immune system. It’s known as a “primary immunodeficiency.” The body’s immune system fights off infections and anything else it sees as foreign invaders to the body. In HLH, the body makes too many immune cells.
https://www.chp.edu/our-services/rare-disease-therapy/conditions-we-treat/hlh-syndromes

