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Welcome Back to Immunohematology

Welcome Back to Immunohematology. Other Antigen Systems Part III – Lewis, P, Lutheran, Xg, I. Lewis System. Primary antigens are Le a and Le b . These are NOT alleles! Antigens are produced in tissues and then adsorbed onto the red cell membrane from the plasma.

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Welcome Back to Immunohematology

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  1. Welcome Back to Immunohematology Other Antigen SystemsPart III – Lewis, P, Lutheran, Xg, I

  2. 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.

  3. 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.

  4. Naturally occurring? HTR? HDFN? Clinically significant? Yes No No No Lewis System

  5. 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.

  6. 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

  7. Naturally occurring? HTR? HDFN? Clinically significant? Yes No No No P System

  8. Lutheran System • Alleles are Lua and Lub. • 92% of Caucasians are Lu(a-b+). • Variable antigen expression between individuals. • Antigens are glycoproteins. • Unaffected by routine enzymes.

  9. 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.

  10. Naturally occurring? HTR? HDFN? Clinically significant? Lua yes Lub no Lub may Lua no Lub may Lua no Lub yes Lua no Lutheran System

  11. I and i • 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.

  12. 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

  13. Naturally occurring? HTR? HDFN? Clinically significant? Yes No No No I and i

  14. Xg System • 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.

  15. Naturally occurring? HTR? HDFN? Clinically significant? No No No No Xg System

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