OTHER BLOOD GROUP SYSTEMS PART 1 (LEWIS, P, LUKE) Flashcards
Antigens in the Lewis blood group system do not develop as integral parts of the red blood cell (RBC) membrane. Instead, they are adsorbed by the [?].
RBCs from the surrounding plasma
• The amount of Lewis antigen varies and depends on:
• Individual’s (?).
• Gradual development of (?).
• Influence of (?) genes.
ABO phenotype and age
Lewis Ag
H, Se, and Le
• Lewis antigen expression may decrease dramatically during.
pregnancy
Lewis
The most common phenotypes include:
• Le(a+b−)
• Le(a−b+)
• Le(a+b+)
• Le(a−b−)
• Most neonates typically type as [?] regardless of inherited Lewis genes.
Le(a−b−)
• Usually IgM but may contain IgG components.
Anti-Lea antibodies
• React best at room temperature but may also react at 37°C.
Anti-Lea antibodies
• Can bind complement and trigger in vitro hemolysis, potentially causing hemolytic transfusion reactions (HTR).
Anti-Lea antibodies
• Anti-Lea or Anti-Leb
is enhanced by enzyme treatment.
Anti-Lea or Anti-Leb
• Usually IgM and react best at room temperature.
Anti-Leb antibodies
• Bind complement poorly.
Anti-Leb antibodies
• Activity is enhanced by enzyme treatment.
Anti-Leb antibodies
• Lewis antibodies may transiently appear during pregnancy in [?] women but disappear after delivery.
Le(a−b−)
• Both [?] react with most cells on routine RBC panels.
anti-Lea and anti-Leb antibodies
• Lewis substance can neutralize these antibodies, allowing the detection of other antibodies present.
anti-Lea and anti-Leb antibodies
• Poorly developed at birth: Lewis antigens are not fully developed in.
newborns
• Reversibly adsorbed onto red cells from plasma: can attach to the surface of red blood cells from the plasma and can be removed under certain conditions.
Lewis antigens
• Not found on cord blood or newborn red cells (Le(a-b-)): Cord blood and newborn red cells typically lack the antigens initially.
Lewis
• Lewis glycolipids detectable in plasma after approximately [?]: It takes around 10 days after birth for Lewis glycolipids tobecome detectable in the plasma.
10 days of life
• Transformation of Lewis phenotype after [?]: Individuals may undergo changes in their Lewis phenotype after birth, transitioning from Le(a-b-) to the true phenotype, which is Le(a-b-).
birth
• Decrease in expression during [?]: Expression of Lewis antigens on red blood cells can decrease in pregnant women, leading to a Le(a-b-) phenotype during pregnancy.
pregnancy
Do not exhibit dosage effects in serologic reactions. This means that the presence of one or two copies of the gene does not affect the strength of the antigen reaction in serological testing.
Lewis antigens
• Naturally occurring: are typically present in the serum without prior sensitization to foreign antigens.
Lewis antibodies
• Predominantly IgM: These antibodies are primarily of the IgM class, which means they are relatively large and can agglutinate red blood cells efficiently.
Lewis
• May cause in vivo hemolysis
Lewis antibodies
•Synthesis and Structure: Lewis blood group antigens are produced by tissue cells and secreted into body fluids.Those in secretions are [?], while those absorbed onto red blood cell membranes are [?].
glycoproteins
glycolipids
•Genetic Basis: The Le gene codes for [?], necessary for Lea expression, while Le and Se genes are needed for Leb expression.
L-fucosyltransferase
•Antigen Formation: Lea antigen is formed by adding [?] to a specific carbon of [?], while Leb antigen requires a second addition of L-fucose to a specific carbon of N-acetylglucosamine.
L-fucose
N-acetylglucosamine
•Phenotypes andSecretor Status: Le(a-b-) individuals are [?] and have only [?], while Le(a-b+) individuals are [?] and have both [?].
ABH nonsecretors; Lea substance
ABH secretors; Lea and Leb substances
The most common phenotype in both white and black populations is [?], with the [?] being more common among blacks.
Le(a-b-)
lele genotype
are poorly expressed at birth and do not exhibit dosage effects in serologic reactions.
Lewis antigens
•Antibodies: Lewis antibodies, typically [?] and [?], can bind [?] and are enhanced by [?].
IgM; naturally occurring
complement; enzymes
Lewis substance in [?] can neutralize these antibodies. They are frequently encountered in [?] but are not considered significant in [?].
secretions
pregnant women
transfusion medicine
• Traditionally, the P blood group included [?].
P, P1, Pk antigens, and later, Luke (LKE)
• In the [?] nomenclature:
International Society of Blood Transfusion (ISBT)
are assigned to the P1Pk blood group system
• P1 and Pk antigens
is assigned to the globoside blood group system
• P antigen
(003, P1PK).
• P1 and Pk antigens
(028, symbol GLOB).
• P antigen
are assigned to the Globoside Collection
• LKE and PX2
(029, GLOB)
• LKE and PX2
• The P1PK gene is located at chromosome
22q11.2.
• The Pgene is located at chromosome
3q26.1.
• Biosynthetic Pathways: There are two distinct pathways for synthesizing P blood group antigens.
• Pathway on the left results in paragloboside and P1 antigens
• Pathway on the right leads to the production of the globoside series: Pk, P, and LKE antigens.
• Common precursor:
Lactosylceramide (or Gb2, also known as ceramide dihexose or CDH).
is also a precursor for the ABH antigens.
Paragloboside
• Pathway on the right leads to the production of the globoside series:
Pk, P, and LKE antigens.
: Common phenotype (about 75% of the population) with both P and P1 antigens.
is well developed at birth
is poorly developed at birth.
1.P1 Phenotype
P antigen
P1 antigen
: Common phenotype, individuals have only P antigen.
2.P2 Phenotype
: Very rare, individuals have both P1 and Pk antigens.
3.Pk1 Phenotype
: Very rare, individuals have both P2 and Pk antigens.
4.Pk2 Phenotype
: Extremely rare, RBCs are negative for P, P1, and Pk antigens.
- p Phenotype
: Naturally occurring, cold-reacting, IgM antibodies often found in individuals with P2 phenotype.
1.Anti-P1 Antibodies
Rarely react at temperatures higher than room temperature, but they can bind complement.
1.Anti-P1 Antibodies
Not associated with hemolytic disease of the newborn (HDN) and rarely cause hemolytic transfusion reactions (HTR).
1.Anti-P1 Antibodies
Produced by individuals with Pk1 or Pk2 phenotypes, can cause severe HTR.
- Anti-P Antibodies
[?], also known as the Donath-Landsteiner antibody
Autoanti-P
is a cold-reacting antibody associated with paroxysmal cold hemoglobinuria (PCH).
Autoanti-P
3.Other Antibodies: occur only rarely.
Anti-PP, anti-Pk, and anti-p antibodies
Discovered in 1965 by Tippett et al. in a patient with Hodgkin’s lymphoma.
Luke (LKE) Antigen and Antibody
Luke (LKE) Antigen and Antibody Divides the population into three phenotypes:
Luke+, Luke(w), and Luke-.
Approximately [?] of individuals are Luke+, [?] are weakly positive (Luke(w)), and [?] are Luke-.
84%
14%
2%
Although it segregates independently of the P blood group, it is phenotypically related because the antibody reacts with most RBCs except those with rare P1, P2, p, and Pk phenotypes.
LKE
Individuals with the [?] are always Luke- (or–LKE-).
p and Pk phenotypes
LKE+ individuals can be either
P1 or P2.
The Pk antigen is more strongly expressed on [?] than on LKE- RBCs.
LKE+ RBCs
Only five examples of human [?] are known.
alloanti-LKE
The original antibody was a saline agglutinin reacting best at– 4°C.
Luke (LKE) Antibody
It became a potent hemolysin with enzyme methods and additional complement.
Luke (LKE) Antibody
Other examples of [?] are much weaker and clinically insignificant.
alloanti-LKE
have been associated with parasitic infections.
Anti-P1 antibodies
• Antibodies such as [?] have been linked toearly abortions.
anti-PP1Pk or anti-P
are implicated in causing PCH
• Autoanti-P antibodies
a condition characterized by the sudden destruction of red blood cells in response to cold temperatures.
Paroxysmal Cold Hemoglobinuria (PCH)
• Certain strains of Escherichia coli associated with urinary tract infections adhere to [?] on uroepithelial cells. This adherence facilitates their ascent in a ladderlike fashion through the urinary tract.
P1 and/or Pk glycolipids
• Streptococcus suis, a bacterium that can cause meningitis and septicemia in humans, binds exclusively to
Pk antigen.
• Toxins secreted by pathogens such as Shigella dysenteriae, Vibrio cholerae, Vibrio parahaemolyticus, and some pathogenic strains of E. coli have binding specificity for the [?].
Gal(α1-4)Gal(β1-4) moiety found in P1 and Pk antigens
• Human parvovirus B19 uses [?] as a receptor for infection.
globoside
•The P blood group comprises the antigens [?], which are biochemically related.
P, P1, Pk, andLKE
•There’s a biochemical relationship between
the P blood group antigens and the ABH and I antigens.
•Produced by all p individuals early in life without RBC sensitization.
Anti-PP1PkAntibody
•Reacts with all RBCs except those of other p individuals.
Anti-PP1PkAntibody
•Antibodies may be a mixture of IgM and IgG, efficiently bind complement, and may demonstrate in-vitro hemolysis.
Anti-PP1PkAntibody
• Found as a naturally occurring alloantibody in the sera of all p
Anti-P Antibody
• Usually caused by autoantibodies demonstrating anti-P specificity.
Paroxysmal Cold Hemoglobinuria (PCH)
PCH autoantibodies are (?) hemolysins typically detectable only by the Donath-Landsteiner test.
IgG biphasic
