Human red cell membrane adenylate cyclase in normal subjects and patients with hereditary spherocytosis, sickle cell disease and unidentified hemolytic anemias

We have investigated adenylate cyclase in ghosts from normal and pathologic human red blood cells. Basic parameters such as specific activity, apparent Michaelis constant (KMapp), and response to effectors: sodium fluoride (NaF), 5′-guanylyl imidodiphosphate (Gpp (NH)p), isoproterenol, and PGE1 were investigated. Basal and NaF- stimulated activities were measured in ghosts from patients with hereditary spherocytosis, sickle cell disease, and various unidentified hemolytic anemias. Both activities were increased in any of these pathologic conditions as compared with those of normal red blood cells. Normal values were found in patients with hereditary spherocytosis after splenectomy and in patients with heterozygous sickle cell disease. There was a good correlation between the reticulocyte count and adenylate cyclase activity in hereditary spherocytosis and in sickle cell disease with reticulocyte count lower than 10%. The enzyme activity of the first group was about three times that of the second group. There was no correlation at all in sickle cell disease with higher reticulocytosis and in the group of unidentified hemolytic anemias. These results suggest that increased adenylate cyclase activities are not specific of any of these diseases. In the patients with hereditary spherocytosis, the adenylate cyclase activity seems to be essentially related to younger mean age of red blood cell population while in the patients with sickle cell disease and in others with unidentified hemolytic anemias some additional factors might interfere directly with the enzyme and alter its activity.