Rh and LW Flashcards
Rh + means
presence of D antigen
Rh - means
absence of D antigen
D antigen is present on only what?
RBCs
clinical significance of Rh antigen
high immunogenicity
other Rh antigens
50 others
most common: D, C, E, c, e
3 theories of Rh gene inheritance
Wiener
Fisher-Race
Tippet
Fisher-Race theory of Rh gene inheritance
3 closely linked loci inherited as a unit
D C E
1 gene 1 product per allele
letter designations
dosage definition
amount of Ag present on a homozygous cell vs. amount of Ag present on a heterozygous cell
genotype determination of dosage
can estimate genotype based on the rxn stregth of phenotyping results
R2 cells
cDE
stronger expression of D
react more strongly with anti-D reagent
Gene position effect of antigen strength: cis effect
labialization of ligands that are cis to other ligands
E antigen produced by R2 gene (cDE) is _____ than E antigen produced by r gene (cdE)
weaker
R1 cells
CDe gene
weak D
Du
less antigenic sites
c gene in trans position to D results in
D antigen weaker expression
partial D, D mosiac, D variant
lack of a part of the D antigen
blood donors (testing for D antigen)
tested for weak D and D
blood recipients (testing for D antigen)
tested for D not weak D
Ce (rhi) R1 gene (CDe)
Ce on same haplotype
ce (f)
c and e on same haplotype
G antigen
present on most D+ and all C+ cells
anti-G combo antibody created in response
D negative person makes both anti-__ and anti-___
anti-D
anti-C
Rh negative person can make anti-G antibody to the ___ antigen
G
LW antigens
present on most human RBCs
D neg have weaker LW activity
anti LW
reacts with D pos cells
weakly with D neg cells
Rh null
very rare
no Rh antigens
absence of regulator genes
“amorph”
RBC membrane abnormalities
Rh null blood type must transfuse with what blood type?
Rh null
immunogenicity of Rh antibodies ranked least to most
least=> most
e< C< E< c< D
antibodies that exhibit dosage
dependent on hetero/homozygosity
anti-E vs anti-e
anti-C vs anti-c
R1 (CDe) patients can create what anti- “combo”
if we find anti-E always type for anti-c
reagent albumin must always have an Rh control because of what?
spontaneous agglutination of the albumin reagent
Rh discrepancies are mostly due to what?
positive DAT
sensitized patient cells + high protein reagents = positive Rh (spontaneous agglutination)
what is the resolution for a positive Rh control?
wash cells w/ saline 3x and redo testing
perform a DAT
retest with a low protein reagent
false positives in Rh testing
wrong reagent added
contaminating Ab
polyagglutinable RBCs
autoagglutinins/ ab. proteins
contaminated reagent
false negatives in Rh testing
wrong reagent added
reagent not added
variant antigen
procedural
weak agglutination
contaminated reagent
