Oxygen Affinity in Hemoglobin Köln Disease

Oxygen affinity studies in a splenectomized patient with sporadically occurring Hb Köln disease revealed high whole blood oxygen affinity (P₅₀ O₂ 17.6 mm Hg) with increased 2, 3-diphosphoglycerate (DPG), low ATP, and normal RBC ΔpH. Isolated electrophoretically slow migrating Hb Köln had a high oxygen affinity, decreased Hill’s number, and normal DPG reactivity. Functional evidence for hybrid tetramers with normal mobility is presented. Partial deoxygenation may play a role in the denaturation of the Hb Köln molecule and thus account for a higher oxygen affinity (low P₅₀ O₂), measured by the mixing technique, than the actual values for P₅₀ that exist in vivo. Increased oxygen affinity and decreased P₅₀ O₂ would result in increased erythropoiesis and account for a well-compensated hemolytic process in this patient with a normal red cell mass and normal values of hemoglobin.