HP and multiple sclerosis: The sudden release of Hb from ruptured RBCs into the blood plasma can result in kidney failure if the binding capacity of the plasma protein haptoglobin (Hp)—which tightly binds to Hb in the blood plasma to form a Hp-Hb complex—is overwhelmed.14 The fact that Hp-Hb complexes have been detected in the blood plasma of multiple sclerosis patients, stroke patients,7 and healthy controls implies that the rupture of RBCs does not appear to adversely affect human health as long as the continuous removal of cell debris, including Hb from the bloodstream is not compromised.