TREM2 and supranuclear palsy, progressive, 1: In PSP, higher numbers of classical monocytes and natural killer cells, associated with lower numbers of TREM2+ cells, were associated with shorter survival.28 Furthermore, genetic variations at the leucine-rich repeat kinase 2 (LRRK2) locus are also associated with survival in PSP,29 highlighting the mechanistic contribution of immune pathways to PSP progression.