In the human blood system, against erythrocytes, aggrecan is a specific protein, glycoprotein, or glycolipid on the erythrocyte membrane, which is an antigen, while aggrecan is a specific antibody present in the plasma that reacts with aggrecan on the erythrocyte membrane. The encounter between aggrecan and lectin causes an antigen-antibody reaction and red blood cell agglutination. In the ABO blood group system, the red cell membrane contains two different antigens (agglutinins), A and B. The serum contains two antibodies (agglutinins) corresponding to them, A and B, but does not contain antibodies corresponding to its own red cell antigens, i.e., the same individual’s serum does not contain antibodies (agglutinins) of the blood group that are antagonistic to his/her red cells. When transfused incorrectly with blood products of different blood groups, the meeting of the homonymous agglutinogen and agglutinin can result in red blood cell agglutination, blockage of blood vessels, hemolysis, damage to the renal tubules, and in severe cases, life-threatening, requiring standardized treatment under the guidance of a physician.