IMMUNOHEMA

• What is the first blood group discovered?

  ABO blood group system
• Why is the ABO blood group system considered the most important in transfusion and transplantation therapy?


  It is crucial for compatibility in blood transfusions and organ transplants
• What does the term "blood group" refer to?

  Genetically encoded RBC, WBC, platelets, and plasma systems
• What is the histo-blood group system?

  ABO epitopes found on tissues and body fluids including RBCs, platelets, and endothelial cells
• Where are the ABH genes located?

  On chromosome 9
• How are ABH genes inherited?

  In a codominant manner following simple Mendelian genetics laws
• Where are ABH antigens found in the human body?

  In most secretions and tissues
• What are ABO antigens composed of?

  Terminal sugars found at the end of long sugar chains attached to lipids on the red cell membrane
• What is the O antigen characterized by?

  Lack of A and B antigens but presence of H antigen
• What are the blood types and their corresponding genotypes?

  • O: OO
  • A: AA, AO
  • B: BB, BO
  • AB: AB
• What are the parent alleles and their possible offspring combinations for blood types?

  • A x A: AA, AO
  • A x B: AB, AO, BO
  • A x O: AO
  • B x B: BB, BO
  • B x O: BO
  • O x O: OO
• What do ABO genes code for?

  Production of glycosyltransferases that add immunodominant sugars to a basic precursor substance
• What is the role of transferases in antigen formation?

  They catalyze the addition of specific sugars to the oligosaccharide chain
• What does the H gene code for?

  1. fucosyltransferase enzyme
• How is the H gene inherited?

  Independently of ABO genes
• What is the Se gene responsible for?

  Controls the appearance of ABH antigens in body fluids
• What does the presence of the Se gene determine?

  Whether ABH soluble substances will be secreted
• What is a secretor?

  An individual who secretes A, B, or H substances in saliva and other body fluids corresponding to their blood type
• What controls secretor status?

  The Sese genes
• How can ABH soluble substances be detected?

  Through saliva, tears, urine, digestive juices, bile, milk, and amniotic fluid
• When does the attachment of immunodominant sugars occur on the RBC membrane?

  On the 37th day of fetal life
• What are the characteristics of ABO antibodies?

  • Mostly naturally occurring
  • Detectable 3 to 6 months after birth
  • Mostly IgM
  • React best at room temperature or below
• What are the blood groups and their corresponding antigens and antibodies?

  • Group O: Antigen H, Antibodies Anti-A, Anti-B, Anti-AB
  • Group A: Antigens A, H, Antibody Anti-B
  • Group B: Antigens B, H, Antibody Anti-A
  • Group AB: Antigens A, B, H, No antibodies
• What is the frequency of blood type O in whites and blacks?

  45% in whites and 49% in blacks
• What is the purpose of forward grouping in blood typing?

  To determine the presence or absence of antigens
• What is the purpose of reverse grouping in blood typing?

  To determine the presence or absence of anti-A/B antibodies in serum
• What are the characteristics of group O and group AB blood types?

  • Group O: Universal donor of RBCs, universal recipient of plasma
  • Group AB: Universal recipient of RBCs, universal donor of plasma
• What are the interactions of the Sese, Zz, and ABH genes?

  • Sese system: Regulates formation of H antigen and ABH antigens in secretory cells
  • Zz system: Regulates production of H antigens on erythrocytes
• What are the differences between ABH antigens and ABH soluble substances?

  • ABH Antigens: Found in red cells, epithelium tissues, BM, other cells
  • ABH Soluble substances: Found in all body secretions
• What are the subgroups of A and B blood types?

  • Inherited conditions caused by decreased amounts of Ag on RBC
  • Most common are subgroups of A (80% A's and AB's have normal expression of A1)
• What are the characteristics of A1 and A2 cells?

  • A1 cells: More antigenic sites for H antigen
  • A2 cells: H antigen sites occupied by both A and A1 antigens
• What type of antigens does the A1 cell have compared to the A2 cell?

  A1 cell has more antigenic sites for H antigen than A2 cell.
• What reaction occurs with Anti-H lectin in A1 cells?

  A1 cells show a positive reaction with Anti-H lectin.
• What is the relationship between H-substance and ABO groups?

  1. substance is an antigen that is related to the ABO blood groups.
• What are B subgroups associated with?

  B subgroups are infrequent and associated with Anti-B lectin from Bandeiraea simplicifolia.
• When was the Bombay phenotype first reported?

  The Bombay phenotype was first reported in 1952 in Bombay, India.
• What is the genotype associated with the Bombay phenotype?

  The genotype associated with the Bombay phenotype is hh or Hnull.
• What is the significance of the allele h in the Bombay phenotype?

  The allele h is very rare and does not produce the L-fucose necessary for the formation of H structure.
• What infections are associated with acquired A antigens?

  Acquired A antigens are reported in persons of type O or B associated with severe infections caused by Proteus mirabilis.
• What conditions are associated with acquired B antigens?

  Acquired B antigens are associated with conditions such as carcinoma of the colon or rectum, intestinal obstruction, and septicemia caused by Proteus vulgaris.