Blood types and immune response The role of proteins – antigens and antibodies – in producing human blood types.

Blood Types/Blood Groups  Blood types refer to specific groups of proteins found on cell membranes of erythrocytes  Numerous groups of blood type proteins, making several types of blood types  Blood types include: ABO; Rh; MN; Le; K  We will focus on ABO and Rh

Blood types/Blood Groups O and A are the most common ABO types Rh+ is the most common Rh form

Proteins and blood types  Two kinds of protein involved with blood types – antigen and antibody  Antigen  Proteins found on RBC membrane  Each has a specific shape  Antibody  Proteins found in blood plasma  Have a binding site built for a specific antigen

Antigens, Antibodies and Blood types ABO Blood Group  (2) Antigens = A and B  (2) Antibodies = anti-A and anti-B  (4) Blood Types = A, B, AB, O Rh Blood Group  (1) Antigen = Rh  (1) Antibody = anti-Rh  (2) Blood Types = Rh + and Rh –

Antigens, Antibodies and Blood types Type A = A antigen; anti-B antibody Type B = B antigen; anti-A antibody Type AB= A + B antigen; no antibody Type O = no antigen; anti-A + anti-B antibodies

Antigens, antibodies and agglutination Agglutination (clumping of RBCs) occurs when: Agglutination (clumping of RBCs) occurs when: Anti-A antibodies bond with A antigens Anti-A antibodies bond with A antigens Anti-B antibodies bond with B antigens Anti-B antibodies bond with B antigens

Blood Types and Blood Transfusions  Agglutination can occur in blood transfusions if:  Anti–A antibodies are mixed with A antigen  Anti–B antibodies are mixed with B antigen  As a result, transfusions can occur between blood types where antibodies do not mix with specific antigens  A blood can receive from A and O blood types  B blood can receive from B and O blood types  AB blood can receive from A, B, O and AB blood types  O blood can receive from O blood types  O is the ‘universal donor’  AB is the ‘universal recipient’

Blood Types and Blood Transfusions Blood TypeAntigens on red blood cell Antibodies in plasma Can receive blood from Can donate blood to AAAnti-BA and OA and AB BBAnti-AB and OB and AB ABA and BNoneAB, A, B, OAB only ONoneAnti-A Anti-B O onlyO, A, B, AB Universal Recipient Universal Donor

Testing for Blood Type  Mix unknown blood with serum containing known antibodies (anti-A + anti-B)  Look for agglutination  Both clump = AB  Anti-A clump = A  Anti-B clump = B  Neither clump = O

Rh blood group  Presence of Rh (D) antigen = Rh +  Absence of Rh (D) antigen = Rh –  Rh antibodies are not normally present, but are produced in response to antigen exposure  First exposure does not produce agglutination (no antibodies)  Second exposure will produce agglutination (antibodies present)  Transfusions  Rh– to Rh+ is OK  Rh+ to Rh– is not OK

Rh Blood Groups and Pregnancy During pregnancy/childbirth an Rh– women with an Rh+ baby may become exposed to the Rh antigenDuring pregnancy/childbirth an Rh– women with an Rh+ baby may become exposed to the Rh antigen In a subsequent pregnancy her Rh antibodies will attack the baby’s red blood cells causing agglutinationIn a subsequent pregnancy her Rh antibodies will attack the baby’s red blood cells causing agglutination Prevented by giving women an injection that shields the Rh antigen from detection and prevents production of Rh antibodies in the motherPrevented by giving women an injection that shields the Rh antigen from detection and prevents production of Rh antibodies in the mother