Pg 145 The four different blood groups A B AB O The four different blood groups • The proteins found on the surface of the RBC are also known as antigen. Note: These antigens do not stimulate the lymphocytes to produce antibodies. The four different blood groups • Classification of blood types are based on the type of antigens found on the surface of red blood cells. ‘Natural antibodies’ • Natural antibodies found in our blood. Natural antibodies Antibodies Occurs naturally and Produced only in the always present in the body. presence of foreign objects like bacteria/virus. • Antigens react with antibodies. Agglutination of blood • Clumping / agglutination of blood occurs when: – Antigen A reacts with antibody a – Antigen B reacts with antibody b Agglutination of blood • Blood clumps block up small blood vessels and obstruct the flow of blood. What happens when different blood groups are mixed in blood transfusion? • Blood donors • Blood receivers • Agglutination of donor’s RBCs Why is blood group AB called the universal acceptor? • Absent of antibodies in the plasma. • No reaction with antigens on other RBCs. • “AB – sounds like acceptor” Why is blood group O called the universal donor? • No surface antigen on blood group O. • Will not react with natural antibodies in other blood group. • Antibodies a and b in the donor’s plasma would be diluted by the recipient's blood. • Hence no effects of the antibodies on the recipient's RBC. In summary Blood group A B AB O Receive blood from A,O B,O A,B,AB,O O Testing for blood group Unknown X Check for Agglutination Antigen A – antibody a Antigen B – antibody b Antibody A Antibody B Test Yourself [pg145] a) X – Blood group B Y – Blood group AB Z – Blood group O b) Serum from A contains antibody B. reacts with antigen B found on RBC to cause clumping. Test Yourself [pg145] C) Blood group O d) A, AB e) No surface antigen to cause agglutination of RBC. Antibodies a and b in the donor’s plasma would be diluted by the recipient's blood. Hence antibodies has no effects on the recipient's RBC.