4 Flashcards
What is the MNS Blood Group System ISBT number?
002
When was the MNS Blood Group System discovered?
1927
What is the significance of the MNS Blood Group System?
It produces naturally occurring antibodies.
How many antigens are in the MNS Blood Group System?
More than 46 antigens.
Which antigens are commonly encountered in clinical settings?
M/N and S/s.
Where are MNS blood group antigens expressed?
Only on red blood cells (RBC).
How many M/N and S/s epitopes are present per RBC?
Approximately 1 million M/N and 170-250 thousand S/s.
What is the common phenotype for MNS blood group?
M+N+ and S-s+U+.
What are M and N antigens associated with?
Glycophorin A.
What destroys M and N antigens?
Ficin, papain, bromelin.
What is the amino acid difference between M and N?
M has serine and glycine; N has leucine and glutamic acid.
What are S and s antigens associated with?
Glycophorin B.
How many amino acids are in S and s antigens?
72 amino acids.
What is the amino acid difference between S and s?
S has methionine; s has threonine.
What type of antibodies are Anti-M and Anti-N?
Naturally occurring antibodies of IgM isotype.
How are Anti-M and Anti-N usually detected?
As room temperature saline agglutinins.
What can destroy Anti-M and Anti-N antibodies?
Proteolytic enzymes and neuraminidase.
What enhances the reactivity of Anti-M and Anti-N?
Acidification of serum to pH 6.5 and use of an albumin diluent.
What is the clinical significance of Anti-M and Anti-N?
Clinically insignificant as long as it does not react at 37°C.
What can Anti-N be used for?
Paternity testing.
What is Autoanti-N?
An autoantibody reported in hemodialysis patients.
What causes Autoanti-N?
Formaldehyde reacting with terminal leucine on N and ‘N’ antigens.
What is Alloanti-N?
A potent hemolysin observed in GYPB deficient patients.
What are the clinical implications of Anti-S, Anti-s, and Anti-U?
Always clinically significant; causes HTR and HDFN.
What is the isotype of Anti-S, Anti-s, and Anti-U?
IgG isotype, reactive at 37°C.
What is the most common null phenotype?
U-.
What is the Henshaw phenotype?
A recombinant glycophorin B that can react weakly with some human anti-U.
What is En(a-)?
Results from recombination of glycophorin A and B genes.
What is the biological role of Glycophorin A and B?
Still unknown; their absence is not associated with known hematologic or pathologic sequelae.
What is the P Blood Group System ISBT number?
003 and 028.
What antigens are included in the P Blood Group System?
P1, Pk, and P.
What are the characteristics of P1 antigen?
Uniquely expressed on RBCs; poorly expressed at birth.
What is the expression rate of P1 in Caucasian and black donors?
Approximately 79% of Caucasian and 94% of black donors.
What are P and Pk antigens known for?
High-frequency antigens on most donor RBC (>99.9%).
What is Anti-P1?
A naturally occurring antibody of lgM isotype that may cause immediate and delayed hemolytic transfusion reactions (HTRs).
IgG forms are rare, thus no hemolytic disease of the fetus and newborn (HDFN).
What are the characteristics of Anti-P1?
Can bind complement, often detected as a weak, cold-reactive saline agglutinin, and reacts optimally at 4°C.
Not commonly seen in routine testing.
What factors affect the reactivity of Anti-P1?
May not react with all P1 positive cells tested due to variable P1 expression strength between individuals.
Rare examples may react at 37°C or show in vitro hemolysis.
In which conditions are titers of Anti-P1 often elevated?
Titers are often elevated in patients with parasitic infections and Bird Fancier’s Lung.
Examples of infections include Hydatid disease and fascioliasis.
What sources can be used for neutralization of Anti-P1?
Hydatid cyst fluids, pigeon droppings, turtledoves’ egg whites, Lumbricoides terrestris, and Ascaris suum.
What is the Anti-P, P1, Pᵏ antibody?
A separable mixture of anti P, Anti P1, and Anti Pk, historically known as anti Tja, naturally occurring in ‘p’ (P Null) phenotypes.
What are the characteristics of Alloanti-P?
A naturally occurring IgM alloantibody in the serum of Pk (and p) individuals that can cause in vivo hemolysis following transfusion of P positive RBCs.
What is Autoanti-P?
Also known as Donath Landsteiner antibody, it is an autoantibody with anti p specificity seen in patients with Paroxysmal Cold Hemoglobinuria (PCH).
What is the biological role of the Pk antigen?
Evidence suggests it may be associated with c-interferon and major histocompatibility class I receptors, modulating cell signaling via lipid rafts.
What role do P blood group antigens play in cellular processes?
They may play a role in cellular differentiation and neoplasia, and are differentially expressed during embryogenesis, hematopoiesis, and intestinal mucosal differentiation.
What is the significance of the LKE (Luke Antigen)?
Formed by the addition of galactose and sialic acid, it is a marker of embryonic and mesenchymal stem cells implicated in adhesion, cell signaling, and metastasis.
What pathogens can P blood group antigens act as receptors for?
P blood group antigens are receptors for Parvovirus B19, HIV, Shiga toxins, and P-fimbriae from Uropathogenic E. coli.
What is the Lutheran blood group system?
Contains 27 antigens, poorly developed at birth, and does not reach adult levels until age 15.
What are the characteristics of the Lu(a-b-) phenotype?
Can occur in three settings with distinct patterns of inheritance: autosomal recessive, autosomal dominant, and X-linked recessive.
What is the significance of Lutheran antibodies?
Not clinically significant, rarely associated with HDFN and hemolytic transfusion reactions.
What is the Kell and Kx blood group system?
Kell and Kx are anchored to one another by disulfide bonds, first identified in 1945, and have significant immunogenicity.
What are the characteristics of K0K0 phenotype?
An autosomal recessive null phenotype that completely lacks all Kell antigens and can produce alloantibodies to Kell glycoprotein.
What are Kell antibodies?
Clinically significant IgG antibodies associated with immediate and delayed hemolytic transfusion reactions and HDFN.
What is Anti-K1?
Antibody against K, most commonly encountered antibody against the Kell blood group system.
What percentage of pregnancies encounter Anti-K1?
Present in approximately 1% of pregnancies, with HDFN affecting 40% of K1 positive infants.
What is the biological role of Kell?
Kell cleaves endothelin-3, a vasoactive peptide involved in endothelial cell migration, neovascularization, axonal growth, and neural crest development.
What is McLeod Syndrome?
Hematologic neuromuscular abnormalities typically presenting with areflexia, dystonia, and choreiform movements late in life.
What are the characteristics of McLeod RBCs?
Shortened survival, decreased permeability to water, and abnormal morphology (acanthocytes).
What is the Lewis blood group system?
Named after one of the first individuals to make antibody, it consists of 6 antigens: Lea, Leb, Leab, LebH, Aleb, Bleb.
How are Lewis antigens synthesized?
Lewis antigens are synthesized in the gastrointestinal tract and passively adsorbed onto RBCs from a soluble pool of secreted Lewis substance in plasma.
What are the three Lewis phenotypes observed in adults?
Le (a+b-), Le (a-b+), and Le (a-b-). Most common is Le (a-b+).
What is the significance of Anti-Lea and Anti-Leb antibodies?
Naturally occurring IgM, seldom clinically significant, and can be enhanced by pretreatment of RBCs with enzymes.
What is the biological role of Lewis antigens?
Linked with a higher incidence of recurrent Candida vaginitis and urinary tract infection, and protects against Norovirus infection.
What is the Duffy blood group system?
Discovered in 1951, named after Mr. Duffy, a multiply transfused hemophiliac who was found to have anti-Fya.
What are the Duffy phenotypes?
Most common is Fy (a-b+), with the majority of African Americans having Fy (a-b-) Null.
What are the characteristics of Duffy antibodies?
Clinically significant, IgG isotype, reactive at 37°C, associated with HDFN and both immediate and delayed hemolytic transfusion reactions.
What is the biological role of DARC?
May facilitate leukocyte recruitment to sites of inflammation by establishing a chemokine across activated endothelium.
What is the significance of the Fy null phenotype?
Linked to lower neutrophil counts, susceptibility to infection, renal disease, and reduced graft survival following renal transplantation.
