MIDTERM LECTURE L1: LEWIS BLOOD GROUP Flashcards
T/F: Lewis antigens are intrinsic to RBCs
false (they’re not)
Lewis antigens are located on what type of lipid
type I sphingolipids
Lewis antigens from the plasma are passively adsorbed unto what
RBC membranes
Lewis system was named by
mourant (1st individual to make its antibody)
What year did Mourant named the lewis system
1946
Lewis ISBT system number and symbol
007
LE
In what year was anti-leb discovered to react with Le(a-) individuals
1948
T/F: Lea and Leb are antithetical antigens
F
(they’re not antithetical, but scientists initially thought they were)
Why Lea and Leb not antithetical?
because they do not result from alternative alleles of a single gene
The synthesis of Lea and Leb antigens result from the interaction of what (specify how many)
2 fucosyltransferases
2 fucosyltransferases are encoded by what genes
Le and Se (independent genes)
Lewis gene & secretor gene are located on what chromosome?
chromosome 19
Specify the location of Le (FUT3) gene
19p13.3
Specify the location of Se (FUT2) gene
19q13.3
The 2 alleles at the lewis locus
Le and amorph le
The 2 alleles at the secretor locus
Se and amorph se
The Le(a-b-) is found more frequently among which people?
africans
The Le(a+b+) phenotype is rare among whites and africans but is more frequent among which people?
asians
Prevalence percentage of Le(a+b+) among asians
10-40%
T/F: Lewis antigens are expressed on cord RBCs
F
T/F: Lewis antigens often diminish on the mother’s RBCs during pregnancy
T
Soluble lewis antigens are found in what body fluid
saliva (as glycoproteins)
Lewis antigens are manufactured on what tissue sources
- lymphocytes
- platelets
- pancreas
- stomach
- intestine
- skeletal muscle
- renal cortex
- adrenal glands
Lewis antigens are resistant to treatment with what enzymes
ficin and papain
Other treatments that lewis antigens are resistant to
dithiothreitol (DTT)
glycine-acid EDTA
Reactivity of lewis antibodies can be greatly enhanced by testing with
enzyme-treated RBCs
Lewis antibodies are generally what antibodies?
IgM
T/F: Antibodies of lewis antigens do not cause HDFN
T
Why antibodies of lewis antigens do not cause HDFN
because lewis antigens are not well developed on fetal RBCs
2 major lewis antigen
Lea and Leb
Lewis antigens depend on the inheritance of Le genes and what other gene?
Se gene
Lewis antibodies occur quite frequently in the sera of pregnant women who transiently exhibit what phenotype
Le(a-b-)
Most commonly encountered lewis antibody
anti-Lea
Anti-Lea is often detected on tests with what temperature
room temperature tests (sometimes reacts at 37C and IAT)
Can lewis antibodies bind to complement?
yes
Anti-Leb can be classified into what 2 categories?
anti-LebH and anti-LebL
Determine what type of anti-Leb antibody:
Reacts best when both the Leb and H antigens are present on the RBC (such as O and A2 cells).
anti-LebH
Determine what type of anti-Leb antibody:
It represents an antibody to a compound antigen
anti-LebH
Determine what type of anti-Leb antibody:
It recognizes any Leb antigen regardless of the ABO type
anti-LebL
What does the lewis blood group substance in transfused plasma do to the lewis antibodies found in the recepient?
it NEUTRALIZES the lewis antibodies
The lewis gene (FUT3) is linked to what 2 genes that are located at chromosome 19?
Se (FUT2) and H (FUT1)
Genes needed to convert Lea to Leb
Le, H, and Se genes
Identify what phenotype is produced by this set of genes:
Le, se, H
Le(a+b-)
Identify what phenotype is produced by this set of genes:
le, hh, se
Le(a-b-)
Identify what phenotype is produced by this set of genes:
Le, Se, H
Le(a-b+)
Identify what phenotype is produced by this set of genes:
le, Se, H
Le(a-b-)
Identify what phenotype is produced by this set of genes:
Le, weak Se, H
Le(a+b+)
Lewis antibodies are often naturally occurring and made by what phenotype of people
Le(a-b-) individuals
The Lewis and secretor transferases preferentially fucosylate what chains
type 1 chains
H gene (FUT1) preferentially fucosylate what chains?
type 2 chains
Secretor α 1,2-L-fucosyltransferase adds a terminal fucose to the type 1 chain to form what?
type 1H
The Le allele codes for what transferase?
α1,4-L-fucosyltransferase
α1,4-L-fucosyltransferase transfers L-fucose to type 1 H chain on glycoprotein/glycolipid structures to form what antigen?
Leb
Lewis antigens produced in saliva and other secretions are (glycoproteins/glycolipids?)
glycoproteins
Lewis cell-bound antigens absorbed from plasma onto the RBC membrane are (glycoproteins/glycolipids?)
glycolipids
Lewis glycolipids are not detectable in the plasma until about how many days after birth?
10 days after birth
Lex was renamed as
Leab
Lex was renamed as Leab on what year
1998
T/F: Leab is present on all Le(a+b-) and Le(a-b+) RBCs and on 90% cord RBCs
T
What antibody is detected with saline-suspended cells at room temperature, agglutinates, often fragile, and can be easily dispersed if the cell button is not gently resuspended after centrifugation
anti-Lea
(hehe kapoy na)
Enumerate the causes of decreased expression of lewis antigens
- pregnancy
- Cancer
- Alcoholic Cirrhosis
- Viral and Parasitic
- Infection
- Genetic Reasons
Identify if phenotype is ABH secretor or ABH nonsecretor:
Le(a+b-)
ABH nonsecretor
Identify if phenotype is ABH secretor or ABH nonsecretor:
Le(a-b+)
ABH secretor
Identify if phenotype is ABH secretor or ABH nonsecretor:
Le(a-b-)
either ABH secretor or ABH nonsecretor
Identify what antigen this phenotype secretes:
Le(a+b-)
Lea secretor
Identify what antigen this phenotype secretes:
Le(a-b+)
Lea and Leb secretor
Identify what antigen this phenotype secretes:
Le(a-b-)
none
Helicobacter pylori smth smth
Le(a-b+)
