George’s research was focused on understanding the blood. In 1916, he published one important observation. He learned to identify reticulocytes in samples taken from the bloodstream. Reticulocytes are the precursors of erythrocytes, which are mature red blood cells. Reticulocytes are formed in the bone marrow, then expelled into the blood stream. While circulating around the body, they take another day or two to fully develop into erythrocytes. Once he learned to identify and count the reticulocytes, he had a measure of blood creation activity. George could then apply this measure of new blood creation to different treatments and diseases.
He started to focus on a disease called pernicious anemia. Patients with pernicious anemia typically exhibit symptoms of fatigue and weakness. The symptoms progress and sometimes abate for a time, but inevitably lead to death within a few years of diagnosis. One of the difficulties in finding a treatment for this disease was the occasional remission. Fatigue and weakness were not easily quantifiable, and it wasn’t clear exactly when the remission would begin or end. So, identifying the agent responsible for the remission was difficult.
In one study, George observed how 15 patients with this disease responded after removal of the spleen. He noted a significant increase in the reticulocyte count in these patients that coincided with remission of the observable symptoms. Although, the effect was temporary and the disease’s symptoms soon returned, the ability to quantify the disease with counts of reticulocytes was groundbreaking.