Rh Flashcards
Rh genes and location
RHD, RHCE
Chromosome 1
cause of most D- phenotype
complete deletion of RHD gene
Most prevalent Rh phenotypes in whites?
R1 (42%) > r (37%) > R2 (14%) > Ro (4%)
Most prevalent Rh phenotypes in Blacks?
Ro (44%) > r (26%) > R1 (17%) > R2 (11%)
Characteristics of Rh antibodies
IgG; rarely IgM
Do not activate complement
- Causes extravascular hemolysis
Enhanced by enzymes
Rh most to lease immunogenicity
D > c > E > C > e
What is anti-f?
f is present with c and e are in cis
present on Ro and r cells
Appears to be anti-c and -e, but only reacts to shared determinate
What is anti-G?
reacts with all cells carrying D or C or both
Transfuse D- C- blood
Differentiate in pregnant females for RHIG
What causes anemia in Rh null or Rh mod people
RHag is required for strong cytoskeleton of RBC
Integrity of membrane is compromised
Increased osmotic fragility - abn cation fluxes
Stomatocytes present
What chromosome is RHAG located on?
Chromosome 6
What chromosome is LW located on?
Chromosome 19
What is rr (double bar)
Amorph Rh null
No DCE or LW antigens
RHAG is normal
D deletion with homozygous inactive RHCE genes
% of Whites and Blacks that D+?
85% of whites
92% of blacks
% of Asians and Native Americans that are D+?
99%
Weak D
Quantitative = Less D antigen present Amino acid change occurs inside the membrane May need AHG to detect All D epitopes are present Types 1-3 will not make anti-D
Partial D
Qualitative Missing some D epitopes Many will react as IS Most due to hybrid gene with RHCE gene Amino acid change on external loops of D antigen Can make allo-anti-D to missing epitopes
C in Trans to D
Occurs in Ror’
Steric arrangement if C and D interferes with D expression
What is Ceppellini effect?
D is weaker in Presence of C
R1 is weaker than R2 cells
What partial D’s will type D positive?
III, IV, VII
3 + 4 = 7
What is the function of LW antigen?
It’s an Intercellular adhesion molecule (ICAM)
maker for lymphocyte maturation and differentiation
May help stabilize the erythroblastic islands
Involved in removal of old RBC’s
How do you differentiate anti-D and anti-LW?
LW will react with all cord cells regardless of D type
LW is destroyed by DTT and pronase
Both are resistant to Ficin/papain
DVI
Most common partial D in individuals of European ethnicity
Current FDA reagents have IgM clones selected to be nonreactive with DVI in direct tests
Can make anti-D (fatal HDFN)
Rh antibodies
HDFN
Anti-D and –c can cause severe HDFN
Anti-C, -E, and –e do not often cause HDFN (maybe mild)
Fisher Race and population prevalence of:
R1
DCe
White: 42%
Black: 17%
Asian: 70%
Fisher Race and population prevalence of:
r
ce
White 37%
Black: 26%
Asian: 3%
Fisher Race and population prevalence of:
R2
DcE
White: 14
Black: 11
Asian: 21
Fisher Race and population prevalence of:
R0
Dce
White: 4
Black: 44
Asian: 3
Fisher Race and population prevalence of:
r’
Ce
White: 2%
Black: 2%
Asian: 2%
Fisher Race and population prevalence of:
r’’
cE
White: 1%
Black: <0.01%
Asian: <0.01%
Fisher Race and population prevalence of:
Rz
DCE
White: <0.01%
Black: <0.01%
Asian: 1%
Fisher Race and population prevalence of:
ry
CE
White: <0.01%
Black: <0.01%
Asian: <0.01%
most common weak Ds in African ancestry
DIIIa and DAR
Types as RhD pos at IS
Del
Type as D neg (IS &IAT)
Adsorb and elute anti-D
ceCF
Crawford phenotype
D Epitope on RHCE gene
Pos with gammaclone, neg with most other reagents
ceHAR
D epitope on RHCE gene
Reactive with most anti-D reagent but not ortho bioclone
Immune response to RhD
1st exposure: slow response (up to 4 weeks)
Primarily IgM
Response on restimulation: strong IgG usually within 24 hrs
Peaks usually w/in 6 days
Most Cw and Cx+ are also…
C+
Antithetical antigen to Cw/Cx
Mar (high frequency)
Anti-MAR nonreactive with what phenotypes
Rh null
D- -
CwCw
CxCx
CwCx
Describe differential adsorbtion for anti-G determination
First adsorption r’
Elution:
Anti-C if it’s really a D and C
Anti-G, -C if a G and C
Second adsorption R0
Elution
Negative for D and C
anti-G for G and C
Partial e
Most often found in African Americans
Anti-hrs (-f like)
Anti-hrb (-Ce like)
Rh null amorph
Rh protein, RhAg, and genes
Rh protein: absent
RhAG: reduced
Altered gene: RHD deleted (RHCE present)
Rh null regulator
Rh protein, RhAg, and genes
Rh protein: absent
RhAg: absent
Altered genes: RHAG mutation or deletion
Rh mod
Rh protein, RhAg, and genes
Rh protein: reduced
RhAg: reduced
Altered genes: RHAG mutation
LW(a-b-) associated with
Rh null
LW Antigens
Weaker on D- RBCs
Strong presence on all cord cells (D+ and D -)
Anti-LW
Shows relative D specificity
Non reactive with AET/DTT treated cells
D- -
Missing RHCE gene
Del
Express extremely low amount of D antigen that can only be detected by adsorption elution studies
(Negative IAT)
Found in 10-30% of D- people of Asian ethnicity
DHAR and Crawford antigens
D epitopes on Rhce
Show strong agglutination with some monoclonal D reagents but negative with others
Can still be sensitized to D
Elevated D seen in D- -, Dc-, and DCw- caused by
Replacement of parts of RHCE with RHD sequences
Weak D types that can be treated as Rh pos
1, 2, 3
Weak D types that can make anti-D
11 and 15
Antigens in the RHAG Blood group system (4)
Duclos (RHAG1)
Ol^a (RHAG2)
DLSK (RHAG3 and RHAG4)
