HPR and infection: In the interaction of HDL with T. brucei, HDL is named trypanolytic factor (TLF), because endocytosis of certain HDL subspecies, which contain haptoglobin-related protein (Hpr, TLF-1 [98]) and apolipoprotein L-I (Apo L-I, TLF-2 [99]), causes lysis of T. b. brucei and protects mammalian hosts from infection [100].