Lutheran Flashcards
The Lutheran blood group was first identified in____ when a patient with_____ developed an antibody (____) after receiving a blood transfusion containing Lutheran antigens.
The patient’s name was____, and the blood group was later named after him.
Later, in____, another antibody,____, was discovered.
1945
lupus erythematosus
anti-Luª
Luteran
1956; anti-Luᵇ
The Lutheran (LU) genes are located on chromosome____.
19
The two genes coding for Lutheran antigens are:
• Luª (LUA) – Less common allele
• Luᵇ (LUB) – More common allele
Individuals can inherit different combinations of these alleles:
- Lu(a+b-) (Homozygous for Luª)
- Lu(a-b+) (Homozygous for Luᵇ)
- Lu(a+b+) (Heterozygous for Lua and Lub)
Lutheran Antigen Characteristics
Development and Expression
• Lutheran antigens are detectable as early as_____ of gestation.
10-12 weeks
T or F
• They are poorly developed at birth, meaning that newborns have weak Lutheran antigen expression.
True
• Full expression is only reached at around____ years of age.
15
Lutheran Antigens
Resistant to: (3)
• Ficin and Papain (Enzymes commonly used in blood banking)
• Glycine-acid EDTA (Ethylenediaminetetraacetic acid) (Used to remove certain RBC antigens)
Lutheran Antigens
Destroyed by: (4)
• ______(A proteolytic enzyme that breaks down proteins)
• ______(Another proteolytic enzyme)
• ______ & ______(Used to cleave disulfide bonds)
Trypsin
Alpha-chymotrypsin
DTT (Dithiothreitol)
AET (2-Aminoethylisothiouronium bromide)
Tissue Distribution
Unlike many blood group antigens, Lutheran antigens are not just confined to red blood cells. They are widely distributed in various tissues, including:
■ Brain
■ Lungs
■ Pancreas
■ Placenta
■ Skeletal muscle
■ Hepatocytes (Fetal hepatic epithelial cells)
Lutheran Antigens are exclusive to…
RBCs
The Lutheran blood group system consists of two main antibodies:
These antibodies are rarely encountered in laboratory practice due to the unique frequency of Lutheran antigens.
Anti-Luª
Anti-Luᵇ
Anti-Luª
• Commonly found in____ form but can also be___ (rarely).
• Unusual because it can also appear in___ form, which is uncommon among blood group antibodies.
IgM; IgG
IgA
• Naturally occurring – This means that individuals can develop this antibody without prior exposure to the antigen through transfusion or pregnancy.
Anti-Luª
Anti-Luª
Reaction Characteristics
• Reacts at_____ – Unlike most clinically significant antibodies that react at body temperature (37°C), anti-Luª often reacts at cooler temperatures.
• Some anti-Luª antibodies can bind complement, but this is not common.
room temperature (>37°C)
Clinical Significance
• Not clinically significant in transfusion medicine – There are no documented cases of immediate hemolytic transfusion reactions (HTRs).
• If an HTR does occur, it is very rare and mild.
• Hemolytic disease of the newborn (HDN) associated with it is also mild and uncommon.
Anti-Luª
Anti-Luᵇ
Rarity and Formation
• Very rare antibody because____ is a high-incidence antigen, meaning that nearly everyone has Luᵇ on their RBCs.
• Only the small percentage of individuals who lack Luᵇ (_____) can produce anti-Luᵇ if exposed to Luᵇ-positive blood.
Luᵇ
Lu(a+b-)
Anti-Luᵇ
Nature and Immunoglobulin Type
• Primarily found in___ form, making it more clinically significant than anti-Luª.
• Rarely found in ___ or ____form.
• Reacts at_____– This makes it a warm alloantibody (an antibody formed against a foreign RBC antigen).
IgG
IgM or IgA
body temperature (37°C)
Clinical Significance
• Associated with hemolytic transfusion reactions (HTRs), but they are rare and usually delayed.
• Rarely causes hemolytic disease of the newborn (HDN).
• May cause post-transfusion jaundice, likely due to mild hemolysis after transfusion.
Anti-Luᵇ
Antigen expression
Lu^a
Lu^a and Lu^b
Lu^b
No Lutheran antigens
Give the PHENOTYPE
Lu(a+b-)
Lu(a+b+)
Lu(a-b+)
Lu(a-b-) (Lutheran Null)
Phenotype
Lu(a+b-)
Lu(a+b+)
Lu(a-b+)
Lu(a-b-) (Lutheran Null)
Give the ANTIGEN EXPRESSION
Lu^a
Lu^a and Lu^b
Lu^b
No Lutheran antigen
● Lu (a-b-)
○ Also known as
null lutheran
Dominant Inhibitor Gene):
• The presence of an _____inhibitor gene suppresses the expression of Lutheran antigens on RBCs.
• The Lutheran genes are still present in the genome, but they are not expressed.
In(Lu)
• A person inherits two nonfunctional copies of the Lutheran gene, preventing any production of Luª or Luᵇ antigens.
• This results in true Lutheran-null RBCs, meaning no Lutheran antigens are present.
Recessive (Silent Lutheran Gene):
• The Lutheran-null phenotype occurs only in males due to an X-linked genetic mutation.
• Female carriers do not express the phenotype, but male members of the family will have Lu(a−b−) RBCs.
Recessive X-Linked (Only in Males)
People with Lu(a−b−) phenotype are capable of producing an antibody called_____.
Anti-Lu3
• reacts with all RBCs that have any Lutheran antigen (Luª or Luᵇ).
• Since most people have Lutheran antigens (Luᵇ or Luª), transfusing blood to a Lutheran-null individual is difficult.
Anti-Lu3
