MTAP 1

• Immunohematology is the study of immunologic reactions involving components of blood, dealing with antigens, antibodies, and antigen-antibody reactions.
• Immune response: there is an antigenic stimulation.
• Immunoglobulins come in five types: IgG, IgM, IgA, IgD, IgE.
• Blood group antibodies are mainly confined to IgG & IgM.
• IgG antibodies can coat, but not agglutinate the cells, while IgM antibodies can agglutinate the cells bearing the corresponding antigen.
• IgG antibodies require a reagent that spans the distance to elicit lattice formation, thus enhancing the visualization of the reaction.
• IgM antibodies agglutinate in the saline phase (AHG) and may cause agglutination in the saline phase using albumin/enzymes.
• IgG antibodies are usually immune in nature, can cross the placenta, and react at 37°C, making them highly reactive in vivo; clinically significant.
• Rh antibodies are an example of clinically significant antibodies.
• The Fy (a-b-) phenotype is found frequently in West and Central Africans, supporting the theory of selective evolution.
• Antigens in the Duffy blood group are destroyed by enzymes such as trypsin, ficin, papain, and bromelain.
• Duffy antibodies do not react with enzyme-treated red blood cells.
• Duffy antibodies are clinically significant, with an optimum temperature of 37 o C, and are stimulated by transfusion or pregnancy.
• The Duffy blood group is characterized by predominant genes (codominant alleles) Fy a and Fy b, which code for antigens that are well developed at birth.
• The Duffy blood group shows dosage, with phenotypes including Fy(a-b-) which is rare.
• Either Fy a or Fy b are needed for the merozoite to attach to the red cell.
• Most African-Americans are Fy(a-b-) and are not susceptible to malarial infection caused by Plasmodium knowlesi and P. vivax.
• Duffy antibodies do not bind complement and are not a common cause of hemolytic disease of the newborn (HDN).
• Clinically significant antibodies (IgG) are associated with HDFN and HTR, while clinically insignificant antibodies (IgM) need to be identified since they can mask clinically significant antibodies in vitro if to be assayed at room temperature.
• There are two stages in hemagglutination: Sensitization and Lattice formation/Agglutination.
• Sensitization is the coating phase, achieved by IgG, more so if IgM, and involves the bond holding antigen-antibody complex may dissociate & reassociate until the state of equilibrium is reached.
• There is no substitute for blood and every 3 seconds someone needs a blood transfusion.
• Primary concern in blood donation is the safety of blood donor and blood recipient because “safe blood” gives life, while “unsafe blood” gives infections.
• Blood is the most precious gift that anyone can give to another person - The Gift of Life.
• Donor’s name, father’s/husband’s name, date of birth/age, genfer, residential and office address with phone numbers are needed so that the donor can be informed of any laboratory test abnormality or can be called for future donation.
• Your donation will help save the life of up to 3 people since AABB now recommends component separation.
• A donor recruitment program requires a dedicated recruitment section with trained staff like lab technologist, lab scientist, lab specialist, or MLSO.
• Safe donor selection involves medical interview, collection of information on health and behavior for critical assessment of donors regarding fitness, hemoglobin testing, and weight.
• Donor selection involves identification of low risk populations, donor education and recruitment, encouraging self-deferral based on “Deferral Criteria”, and medical examination before donation.
• Donor selection determines the eligibility of a donor to donate blood.
• Pre-donation information includes documents to give information to donors, general advice about giving blood, deferral information, registration, consent of the donor & demographic information, medical history, physical examination, and laboratory tests.
• Donor selection criteria are essential based on accepted regional/international practice and protect the donor and recipient.
• Donors should not eat or drink anything except water for 12 hours before donation.
• Lattice formation/Agglutination is characterized by the formation of bridges between stabilized red cells resulting in a visible aggregate of red cells.
• Factors affecting the Stage of Sensitization include temperature, pH, and the presence of certain additives.
• Agglutination indicates Du positive, while no agglutination indicates Du negative.
• The direct Antiglobulin Test (DAT) is a type of Coombs test used to detect antibodies or complement proteins attached to the red blood cells.
• The indirect Coombs test detects autoimmune hemolytic anemia.
• Another type of Coombs test is used to detect antibodies produced against foreign red blood cells.
• If weak D is due to suppression, theoretically could give D positive and weak D testing on patients is not required.