Among these are 7 complement proteins (C1RL, C2, CFB, CFH, CFI, CFP and CR2) of the innate immune system, whose levels are all elevated in ME/CFS cases, including CR2 (complement C3d receptor 2), the receptor for Epstein–Barr virus (EBV) binding on B and T lymphocytes. Here, CR2 is linked to myalgic encephalomeyelitis/chronic fatigue syndrome.