Abstract
Due to the burden of infectious diseases, human life expectancy at birth remained about 20-25 years until the end of the 19th century, implying that host defense-which operates at the individual level, and only poorly at that-is barely sufficient at population level. Microbes preceded us by three billion years and evolve much more rapidly. Moreover, protective immunity has been selected at the evolutionary cost of allergy, autoinflammation, and autoimmunity. It is therefore no exaggeration to predict that almost all humans carry inborn errors of immunity, with insufficient or excessive responses to some environmental triggers, infectious or otherwise. Thanks to the remarkable power of its concepts and recent progress in its methods, genetics has finally made it possible to investigate the mechanisms of human immunity at the molecular and cellular levels. Human inborn errors provide countless opportunities to analyze immunity and its derailments in natural conditions, at an unprecedented scale, and are thus a unique asset from both biological and medical perspectives. Hence, the Journal of Human Immunity.