the person responsible for the abo classification system for blood is
ABO blood group system The ABO blood group system is widely credited to have been discovered by the Austrian scientist Karl Landsteiner, who identified the O, A, and B blood types in 1900.[5][6] Landsteiner originally described the O blood type as type "C", and in parts of Europe it is rendered as "0" (zero), signifying the lack of A or B antigen. Landsteiner was awarded the Nobel Prize in Physiology or Medicine in 1930 for his work.[5] Alfred von Decastello and Adriano Sturli discovered the fourth type, AB, in 1902.[7][8]
Coombs test The direct Coombs test is used clinically when immune-mediated hemolytic anemia (antibody-mediated destruction of RBCs) is suspected. A positive Coombs test indicates that an immune mechanism is attacking the patient's own RBCs. This mechanism could be autoimmunity, alloimmunity or a drug-induced immune-mediated mechanism.