Introduction to Immunohematology

MT 306: IMMUNOHEMATOLOGY MLS ENHANCEMENT CLASS PREPARED BY: SAYON, ANDREA | 3RD YEAR - 1ST SEMESTER INTRODUCTION TO IMMUNOHEMATOLOGY Study of blood group antigens and antibodies associated with transfusion and pregnancy  Closely related to the field of immunology because it involves the study of immune response to the transfusion of cellular elements (RBC, WBC, and platelets that can potentially initiate immune responses after transfusion)  RBCs, WBCs, and platelets are cellular components that can potentially initiate immune responses after transfusion (e.g., hemolytic transfusion reaction)     TERMINOLOGIES:  Blood bank - collects, processes/tests, stores, transports, and issues blood and blood components intended for transfusion  GOAL: SAFE TRANSFUSION  Transfusion - procedure in which blood or blood components are transferred from a donor to a recipient      HISTORICAL OVERVIEW OF BLOOD TRANSFUSION In the past, it was thought that blood had a nutritive property and was infused with vitalism -a living force. In modern times, the Food and Drug Administration (FDA) classifies blood as a drug. 1492 - Pope Innocent VIII suffered a stroke. In hopes of curing him, blood was taken from three young men and transfused to the pope. In 1818, the first successful man to man blood transfusion was performed by British obstetrician James Blundell. He successfully transfused human blood to a patient who had hemorrhage during childbirth. The patient's husband was the donor.  Major Concern: CLOTTING DISCOVERY OF BLOOD GROUPS  Aside from clotting of blood, one major reason for many unsuccessful early transfusions was blood compatibility not being understood.  This problem was solved in 1900 when Karl Landsteiner (1868-1943) discovered the ABO blood group system, which earned him a Nobel Prize.  After he published his 1st paper: clumping reaction in blood serum and its relationship to immunity  he studied nearly 4,000 post mortem examination; and  published over 75 articles on his observation on describing agglutination reaction that occur when blood from one individual is brought into contact with blood of another individual  In a series of experiments, he recognized different patterns of agglutination when he combined blood serum from different individuals.  He observed that antigens on the outside of blood cells differed between individuals.  He continued researching until the end of his life and compiled a comprehensive summary of his contributions to medicine in his 1936 book, The Specificity of Serological Reactions.  At the age of 75, he died of heart attack in his laboratory  Blood group antigens are molecules located primarily on the red cell membrane. NOTE: Blood group antigens may also be found in secretions (e.g., saliva, milk) and on endothelial and epithelial cells. When someone is exposed to blood group antigens that they don't have (via pregnancy, transfusion, or transplantation), their immune system might create antibodies against those antigens.  MOST COMMON: ABO & RH  First BGS described, and the most important BGS for transfusion purposes  Initially, blood types were A, B, and C (Karl Landsteiner) later blood type C was renamed Type O  1902 - Decastello and Sturli discovered the fourth blood type: AB Enabled doctors to perform safe blood transfusion  During WW1, blood transfusion (based on Karl Landsteiner blood type theory) saved tens of thousands of life  ABO Blood group naming made it possible to successfully complete the first organ transplantation By nature, ABO antibodies are naturally occurring or pre-formed (meaning, without previous exposure), unlike other blood group antibodies Hence, transfusion of ABO-incompatible blood to recipient can automatically result in acute hemolytic transfusion reaction. Four ABO Blood Types: O, A, B, AB Depends on presence of A, B, and H genes (FUT 1, FUT 2) INHERITANCE: one gene is inherited from father, and another from mother A and B are codominant; O is recessive → thus, if genotype is AO, the phenotype is A.  EXAMPLE 1:        ABO BLOOD GROUP SYSTEM (ISBT 001) INTRODUCTION TO BLOOD GROUP SYSTEM 45 blood group system Assigned with International Society of Blood Transfusion (ISBT) numbers  It is composed of antigens that are produced by alleles at a single genetic locus or at loci that are linked very closely   1 MT 306: IMMUNOHEMATOLOGY MLS ENHANCEMENT CLASS PREPARED BY: SAYON, ANDREA | 3RD YEAR - 1ST SEMESTER  EXAMPLE 2:    Thus a DD genotype or Dd genotype results to RH POS (or D POS) phenotype While dd genotype results to Rh NEG (or D NEG) phenotype (Bombay phenotype) Type of ABO antigen depends on presence of specific immunodominant sugars on their RBCs  Unlike ABO antibodies, Rh antibodies are not preformed. They are only formed during pregnancy or after transfusion. Hence, Rh antibodies are not routinely detected NOTE: H is not an ABO antigen because it is part of ISBT 018. But it is the antigen present in Type O individuals. ABO antigen and antibodies have a reciprocal or inverse relationship. The type of antibodies present in an individual are dependent on which ABO antigen/s is/are absent.    A+ . O-  None   Anti-A, Anti-B ABO antigens are determined via Forward Blood Typing. ABO antibodies are determined via Reverse Blood Typing.     . Do not report as RH NEG yet. Perform WEAK D testing first to determine if patient is really RH NEG  Why? To prevent adverse reactions that can occur if Weak D individuals are exposed to D antigen HEMOLYTIC DISEASE OF FETUS AND NEWBORN (HDFN) AKA Erythroblastosis fetalis, occurs when mother' and infant's blood type is incompatible Most common: ABO HDFN Most severe: RH HDFN Requirement: Father is RH POS; mother is RH NEG  1st pregnancy: if baby is RH POS, mother will be sensitized (or she will form anti-D antibodies)  2nd pregnancy: if baby is still RH POS, mother's anti-D will cross placenta and bind to baby's D antigen → hemolysis → adverse effects on 2nd baby B AB      RH BLOOD GROUP SYSTEM (ISBT 004) First reported by Landsteiner and Weiner; named after rhesus macaque monkey This system is highly complex and is composed of over 50 antigens. But the most important antigen is the D antigen because it is the second most immunogenic antigen after ABO antigens. The Rh-factor became a part of Landsteiner's blood typing system, indicated by a positive or negative qualifier after the blood group, for example: AB+ AInheritance: D is dominant; d is recessive;  But if during 1st pregnancy, baby is RH NEG, mother will be not be sensitized (meaning to say, she will not form anti-D antibodies). She will form anti-D only if exposed to D POS cells. SYMPTOMS OF BABY WITH HDFN:  Before birth, 2nd baby will manifest with anemia or in severe cases, hydrops fetalis (build up of fluid) , or death  After birth, 2nd baby will manifest with hemolytic jaundice, enlarged liver or spleen, difficulty in breathing, or death 2 MT 306: IMMUNOHEMATOLOGY MLS ENHANCEMENT CLASS PREPARED BY: SAYON, ANDREA | 3RD YEAR - 1ST SEMESTER   Universal Recipient - AB+ Universal Donor - O- REFERENCE: Harmening, D. M. (2018). Modern blood banking & transfusion practices. FA Davis. 3