Transcript Welcome Back to Immunohematology

Welcome Back to
Immunohematology
Other Antigen Systems
Part III – Lewis, P, Lutheran, Xg, I
Lewis System
 Primary antigens are Lea and Leb.
 These are NOT alleles!
 Antigens are produced in tissues and then
adsorbed onto the red cell membrane from
the plasma.
 Antigens are glycolipids on the red cell, but
glycoproteins in secretions.
 The most common Lewis phenotype is
Le(a-b+).
 Enhanced by enzymes.
Lewis System Antibodies
 Very common.
 Usually IgM.
 React at immediate spin phase.
 May also be present at 37oC and AHG phases.
 Agglutinates may be fragile.
 Do not show dosage.
 May activate complement.
 Anti- Lea is known for causing hemolysis at 37oC.
Lewis System

Naturally occurring?

Yes

HTR?

No

HDFN?

No

Clinically
significant?

No
P System
 The antigens of the P system are:
 P
 P1
 Pk
 Genes that control expression of these
antigens are NOT alleles.
 Antigens are glycolipids similar to the ABO
system.
 Have variable expression among different
people.
 Enhanced by enzymes.
P System Antibodies
 Anti-P1 is a common cold agglutinin
 Reacts best at 20-25oC or colder
 Usually IgM
 Anti-P may act as a biphasic hemolysin
 Do not show dosage
P System

Naturally occurring?

Yes

HTR?

No

HDFN?

No

Clinically
significant?

No
Lutheran System
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Alleles are Lua and Lub.
92% of Caucasians are Lu(a-b+).
Variable antigen expression between
individuals.
Antigens are glycoproteins.
Unaffected by routine enzymes.
Lutheran System Antibodies
 Antibodies to either antigen are uncommon.
 Anti- Lua
 Naturally occurring
 Usually IgM, but may be IgG or IgA
 Reacts best at room temperature or colder
 Anti- Lub
 Immune
 Most often IgG
 Reacts best at 37oC and AHG
 Show dosage.
 May activate compliment.
Lutheran System

Naturally occurring?



HTR?



HDFN?



Clinically
significant?


Lua yes
Lub no
Lub may
Lua no
Lub may
Lua no
Lub yes
Lua no
I and i
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
I is a high frequency antigen.
Carbohydrate structures related to ABH
antigens.
Born with i; coverts to I by age 18
months.
Variable antigen expression.
Enhanced by enzymes.
I and i Antibodies
 Cold reacting autoantibodies.
 Low levels of autoanti-I present in most people.
 IgM
 Reacts at room temperature or colder
 When present in high titers, may result in vascular occlusion
or hemolysis
 Auto anti-i is very rare.
 Associated with disease processes
 Do not show dosage
 May activate complement
I and i

Naturally occurring?

Yes

HTR?

No

HDFN?

No

Clinically
significant?

No
Xg System
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Only one allele – Xga.
Sex linked gene –X chromosome.
89% of females and 66% of males are
Xga positive.
Destroyed by enzymes.
Rare IgG antibody that reacts at AHG
phase.
Xg System

Naturally occurring?

No

HTR?

No

HDFN?

No

Clinically
significant?

No