TM Lewis

Question 1

Describe how lewis antigens are produced

Answer 1

• made by tissue cells and secreted into the plasma/ other fluids
• they adsorb onto the RBC membrane

Question 2

Which 3 genes interact + give rise to Lewis antigens ?

Answer 2

H (fut-1)
Se (fut-2)
Le (fut-3)

Question 3

Describe Lewis antibodies

Answer 3

• IgM; naturally occurring
• clinically insignificant
• tend to be a nuisance; mask clinically significant Abs
• binds complement (C9 in vitro)
• enhanced by enzymes

Question 4

If patient is: A Le (a-b+), what are the soluble Ags in secretions and Ab expected in plasma ?

Answer 4

• has A, H(h), Se, LeᵃLeᵇ alleles

Ag secretions*: A, H, Leᵃ, Leᵇ

Ab**: anti-B

NOTE:
*this phenotype has Se and H genes = A and H antigens are secreted; Lewis Ag are secreted regardless

**only ABO antibodies are expected in plasma

Question 5

If patient is: Oₕ Le (a+b-), what are the soluble Ags in secretions and Ab expected in plasma ?

Answer 5

• has hh Se/se LeᵃLeᵃ alleles

Ag secretions*: Leᵃ

Ab**: anti-A, -B, -H

NOTE:
*this phenotype does not have H genes +/- Se genes = no ABO Ag to secrete; Lewis Ag are secreted regardless

**only ABO antibodies are expected in plasma; bombay expected to make anti-H

Question 6

If patient is: A₂ Le (a-b-), what are the soluble Ags in secretions and Ab expected in plasma ?

Answer 6

• has A₂, H(h), Se/se alleles

Ag secretions*: A₂ and H

Ab**: anti-B, but NOT anti-A₁

NOTE:
*has H genes but IF this phenotype has Se genes = A and H antigens are secreted; no Lewis Ag

**only ABO antibodies are expected in plasma BUT anti-A₁ is not usually expected in Type A individuals

Question 7

If patient is: B Le (a+b-), what are the soluble Ags in secretions and Ab expected in plasma ?

Answer 7

• has B, H(h), se, Leᵃ alleles

Ag secretions*: Leᵃ

Ab**: anti-A

NOTE:
*this phenotype does not have Leᵇ genes = no Se gene = B and H antigens not secreted; Lewis Ag are secreted regardless

**only ABO antibodies are expected in plasma