Who came up with the different blood types (e.g., A+, O-, etc.)?
According to Britannica.com, the business of classifying blood into various groups or types was first described by Karl Landsteiner in 1901. More specifically, Landsteiner, an Austrian-born U.S. immunologist, discovered the “ABO” system, made up of four groups (A, B, AB, and O) into which all blood can be classified. Apparently it’s the presence or absence of certain “antigens” in your blood that determines type. But that’s just the tip of the iceberg. Further research by Landsteiner and others lead to the discovery of 14 main types of blood group systems. Landsteiner also participated in the discovery of the Rhesus blood factors and the polio virus. You can read more about blood grouping at the WebMD Medical Encyclopedia entry on the s
