C4A and type III hypersensitivity disease: Finally, but only theoretically thus far, based on the function of the CP and the role of the C1 complex in immune complex clearance, inhibition of the proximal part of the CP could increase the risk of symptoms found in immune complex diseases, as is observed in patients with congenital CP deficiencies (C1q, C1r, C1s, C2, and C4) [88].