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)