P3.1 IMHM

• Paragluboside


  Precursor substance for the H Ag
• A,B, H antigens are formed from this basic material
• The formation of A and B antigen requires the formation of H antigen
• If there is no H antigen, there is no formation of A & B antigen
• H gene


  Foundation of the ABO blood group, inherited from the parent
• Possible Genetic Combinations


  • HH
  • Hh
  • hh
• Bombay phenotype or Bombay individual (Oh)


  Inheritance of a rare gene (hh), RBCs are devoid of ABH antigens and therefore fail to react with anti-A and Anti-B and anti-H, No ABH Antigens but with anti-A, anti-B and anti-H
• Type O is the most reactive especially if we use anti-H
• True blood "O" if their RBC subject to ABH typing they will appear Blood group "O"
• Bombay Phenotype


  • hh genotype, No H antigens formed, therefore no A and B antigens, Phenotypes as blood group "O", Anti-A, anti-B, anti A,B and anti-H present in the serum, Can only be transfused with blood from another Bombay (Oh)
• H Deficient Phenotypes


  • Classical Bombay: Absence of H gene, Precursor substance can't be converted to H
  • Parabombay: Weak expression of the H gene, A and B enzymes can be detected but no H enzyme detected
  • H deficient Bombay Non-secretor: ABH are not expressed in red cell but present in secretions
  • H deficient Bombay Secretor (hh, Se): Weak expression of ABH ags but normal expression of ABH substance in the secretions
• Subgroups


  A1, A2, A3, Am, Ax, Ay, Ad, Aend, Aint

  B1, B2, Bm, B3, Bx, Bw, Bel

  A1B, A2B
• Antisera: Anti-A1 lectin: Dolichos biflorus, Anti-B1 lectin: Bandeihaea simplicifolia, Anti-H lectin: Ulex uropaeus
• Secretors & Nonsecretors


  ABH soluble antigens can also be found in all body secretions, Presence is dependent on the ABO genes inherited and inheritance of another set of genes (SeSe,Sese), ABH substances can be detected in the following body fluids (saliva, tears, urine, digestive juices, bile, milk, Pathologic fluids: pleural, peritoneal, pericardial, ovarian cyst)
• In CSF we cannot detect ABH antigen
• Detection of ABH in secretion

  Saliva-sample: 3-5 mL of Saliva, ask the patient to gargle using NSS or water, less viscous compare to sputum, subject heating to inactivate enzymes (CHONS)
• High heat can destroy ABH antigens
• Principle: Agglutination inhibition


  Known cells: "A", "B", "AB", "O"

  Anti-sera: anti-A, anti-B, Anti-H

  Coomb's reagent, gel technology, 2-5% RCS, di mag packed yung rbc
• Contaminated glasswares can be resolved
• Group I Discrepancies


  Often associated with unexpected reactions in the reverse grouping due to weakly reacting or missing antibodies, More common in newborns, elderly patients, patients with leukemia, ABO subgroups, patient with hypogammaglobulinemia or aggamaglobulinemia
• Resolution of Common Group I Discrepancy

  Enhance reaction by incubating patient serum with reagent A and B cells at room temp for 15 to 30 minutes, An autocontrol and O cell control must be tested concurrently
• Group II Discrepancies


  Often associated with unexpected reactions in the forward grouping due to weakly reacting or missing antigens, Causes: Subgroups A or B, Leukemias may yield weakened A or B antigens, Hodgkin's disease, "Acquired B" phenomenon (often associated with diseases of the digestive tract)
• The patient is Blood group "A" in the red cell suspension
• Group III Discrepancies


  Discrepancies between forward and reverse grouping caused by protein or plasma abnormalities and result in rouleaux formation, or pseudoagglutination, Causes: Elevated levels of globulin (e.g., multiple myeloma, Waldenstrom's macroglobulinemia, other plasma cell dyscrasias and advanced cases of Hodgkin's lymphoma), Elevated levels of fibrinogen, Wharton's jelly in cord blood samples, Plasma expander's (dextran and polyvinylpyrrolidone)
• Group IV Discrepancies


  Discrepancies between forward and reverse grouping are due to miscellaneous problems, Causes: Cold reactive antibodies, Patient has circulating RBCs of more than one ABO group due to RBC transfusion or bone marrow transplant, Unexpected ABO isoagglutinins, Unexpected non-ABO alloantibodies