Although innate immune cells and T lymphocytes are well known to respond to IL-12 and IL-23 in a peripheral—that is, a non-central nervous system (CNS) inflammatory—setting9, IL-12/IL-23 actions within the amyloidogenic AD brain are not understood: neither the exact cellular players are known nor whether IL-12 and/or IL-23 individually, or in concert, confer this AD-specific effect. The gene discussed is IL23A; the disease is Alzheimer disease.