Rh antigen Flashcards
What is the second autosomal linkage in humans?
Rh blood group and gene for elliptocytosis
What was the Fisher and Race theory?
3 closely linked genes Inherited has a haplotype Crossover was rare 1 gene = 1 antigen Did not explain all the low freq
What was the Weiner theory?
1 gene codes for 1 agglutinogen that has 3 factors
Each factor represented an antigen
Thought that R and r could code for unlimited factors
What is the ISBT number for Rh?
004
What was Tippetts theory?
Correctly described the 2 gene inheritance
1 RHD gene and 1 RHCE gene
What antigen does ISBT 4.6 code for?
f
What antigen does ISBT 4.7 code for?
Ce
What antigen does ISBT 4.8 codes for?
Cw
Most prevalent Rh phenotypes in whites?
R1 (42%) > r (37%) > R2 (14%) > Ro (4%)
68% of whites are C +
80% are c+
Most prevalent Rh phenotypes in Blacks?
Ro (44%) > r (26%) > R1 (17%) > R2 (11%)
27% are C+
98% are c+
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-RH17?
RH17 = Hro (High freq)
antibody that reacts with all cells except D– and D**
Auto antibody is known as anti-pdl (partial deleted)
What is anti-RH29?
RH29 = total Rh
antibody that reacts with all cells except Rh null cells
Immune stimulated in Rh null
Some anti-RH29 reacts with Rh mod cells
auto antibody is known as anti-dl (total deleted)
What are anti-hr(s) and anti-hr(b)?
antibody reacts with all cells but can look anti-e reacting with stronger with e+ cells. Made by people with variant e. Seen in black population.
What is anti-LW?
Antibody reacts stronger with D+ cells than D- cells
- May need to enhance to show reactivity with D- cell
Negative with Rh null cells
Anti-LW reacts with all cords regardless of Rh type
DTT destroys
Seen as an auto antibody with no clinical significance
Cw
Found with multiple antibodies
Cw is found in 2% of whites
Goa
Goa (RH30) is present in DIVa partial D cells
present in 2% of blacks
V antigen is historically known as
ce^s
RH10
occurs in 30% of blacks
The VS antigen is historically known as
e^s
RH20
occurs in 32% of blacks
What is anti-Evans antibody?
Evans antigen is present on D** cells and not D– cells
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 on Ro and r cells
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 amino acid change makes G antigen?
Serine at position at 103 on RHD and RHCE gene
Anti-Ce
Also called RH7 or rhi
Similar to f, reacts with Ce+ cells in cis (R1 or r’)
Most anti-C is Ce in Rh positive people
Ce is present in 68% of White and 27% of blacks
- Most C+ will be e+
What disease show reduced expression of Rh antigens
Hereditary spherocytyosis Leukemias Myeloid metaplasia Myelofibrosis Polycythemia
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 RHD and RHCE located on?
Chromosome 1
Characteristics of RHD and RHCE genes?
Both are 416 amino acids long with 10 exons
92-97% identical
genes run in opposite direction = “hair pin” formation and genetic recombination
What chromosome is RHAG located on?
Chromosome 6
What chromosome is LW located on?
Chromosome 19
What cells have the most D antigens present?
D–
D**
R2R2
What is the amino acid that determines C
Serine at 103
Ser103Pro
What is the amino acid that determines c
Proline at 103
Ser103Pro
What is the amino acid that determines E
Proline at 226
Pro226Ala
What is the amino acid that determines e
Alanine at 226
Pro226Ala
What is the Rh box?
RHD gene is flanked by 2 Rh boxes
Identity boxes
In whites, Deletion of D gene occurs in RH boxes
What is the structure of D antigen?
Pass membrane 12x Has a C and N terminus in cytoplasma of cell Non-glycosylated = Hydrophobic Non=phosphorlated More than 30 epitopes
What is X1r?
Normal RHAG gene
Makes precursor substance 2 from precursor 1
Must be present to make RH and LW antigens
What is Xor?
No RHAG gene
= Rh null regulator
No Rh antigens or LW antigens
What is Xqr?
Rh mod phenotype
RHAG makes a modified precursor substance 2. DCE and LW antigens are present but weak
What is rr (double bar)
Amorph Rh null
No DCE or LW antigens
RHAG is normal
D deletion with homozygous inactive RHCE genes
High protein Anti-D
Human source = Polyclonal
20-24% protein added to enhance IS of IgG antibody by bringing RBC’s close together
May see spontaneous agglutination with warm auto
IgM Saline anti-D
Human source
Expensive because hard to find donors with IgM Anti-D
Chemically modified anti-D
Human source
DTT breaks the disulfide bonds in the hinge region to allow IgG to crosslink 2 RBC’s
Monoclonal anti-D
Combonations of IgM and IgG
Can be monoclonal IgM with human IgG
or both monoclonal IgG and IgM
What is crawford antigen (ceCF)?
RH43 - Found in Africans 0.1%
amino acid substitution in the RHCE gene that results in a D like epitope
D gene is NOT present.
Negative at IS but reacts at AHG phase
What causes a false positive with anti-D?
Warm or Cold auto antibodies
Rouleaux or spontaneous red cells agglutination
contaminated reagent
Polyagglutination - seen with ortho (human source)
What causes a false negative with anti-D?
Failure to add reagent
RBC suspension too heavy
Shaking tube to hard
Red cells with positive strong DAT (seen in HDFN)
How many D antigen sites are on most normal D+ cells?
10-33,000
How many D antigen sites are on D– or D** cells?
75-300,000
How many antigens are on Weak D cells?
<100-10,000
How many antigens are on Del cells?
> 20
% of Whites and Blacks that D+?
85% of whites
92% of blacks
% of Asians and Native Americans that are D+?
99%
What causes D neg in most Caucasians?
D gene is deleted
Chromosome misalignment and unequal crossing over between the Rh boxes
What is the pseudogene?
Occurs in African populations (66% of Rh-)
There is a premature stop codon which does not allow the D gene to be expressed
D gene is present but inactive
What is the Del phenotype?
Amino acid change that results in very low D antigens on RBC
Will type D- at IS and AHG phase
Must adsorb and elute to detect D antigen
Found in 10-30% Asians
Exon 9, inside the membrane, is deleted
Most are C+ (Rh negative)
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 Many assoc. with low frequency antigens
C in Trans to D
Occurs in Ror’
Steric arrangement if C and D interferes with D expression
D antigen is normal = Can rec’v D+ cells
What is Ceppellini effect?
D is weaker in Presence of C
R1 is weaker than R2 cells
Partial DVI
Found in Whites 0.02-0.05%
Accounts for 6-10% of all partial D’s that make anti-D
BARC+ (RH52; low freq)
Not detected at IS but variably positive in AHG.
FDA Requires that monoclonal anti-D NOT detect DVI at IS, so females are typed as D neg
DVII
Found in Whites
Tar+ (RH40; Low freq)
DIVa
Found in blacks
Goa+ (RH 30; Low freq)
GoDIVa
DIIIa
Found in Blacks Assoc. with Variant RHCE*ce^s Make anti-D, anti-c, or anti-hr^b DAK+ (RH54; Low freq) Consistently strong D epitopes - types D+
What partial D’s will type D positive?
III, IV, VII
3 + 4 = 7
D**
Has D, G, RH29 (total Rh) + RH37 (EVANS)
Has less D antigen than other D deletions
Can make anti-Rh17 and anti-RH47 (DAV
D–
Has D, G, and RH29 Total
D gene is present and homozygous for RHCE null
Most D antigen present
Form anti-e or Ce (Rh 7)
Also, make anti-Rh17 or anti-Hr = Reacts with all common Rh phenotypes
RHD*DHAR
Formerly called RoHAR but better named ceHAR
Found in 0.01% Germans
FPTT+ and RH33
Hybrid CE-D-CE gene = No D antigen; Only one D epitope insertion
R HAR = Normal c, reduced e, f, Hro and D = (D)c(e)
Most IgM reagents detect; can make anti-D
What is Rh null regulator?
NO RHAG protein due to inactivating mutations
Xor
NO DCE, LW, GPB (S, s, U) or FY5 antigens
Reduced CD47
Make anti=RH29 (total Rh)
What is Rh mod?
XQr = RHAG is modified and not expressed normally
Rh antigens are present but weakend
Must adsorb and elute to detect Rh antigens
What is Rh null amorph?
rr (double bar)
amorph from deleted D gene and homozygous for RHCE containing inactivating mutations
Normal RHAG but no DCE, LW. Normal Ss and weak U
Rare, occurs in whites
Frequency of Rh null
One in 6,000,000
Can an Rh Null pass Rh gene to child?
rr and Rh null (R1R1) person can pass one normal RHAG and R1r to child = Rh positive from 2 Rh neg parents
What does the FDA require for weak D on instrument?
Instrument must detect a weak D of 1+ or greater.
Weaker than 1+ will be labeled as Rh negative
What does the RHAG code for?
RH-associated glycoprotein
It carries 4 antigens and Rh core complex
What is Rh core complex?
Interacts with Band 3, GPA, GPB, LW, and CD47 and is associated with the membrane skeleton via Ankyrin and Protein 4.2
What is CD47?
Part of Ig superfamily
Generates a “survival signal”
-Anti-CD47 drug
What is RHAG1?
Duclos Antigen
High incidence
Absent Rh null regulator and Rh mod phenotype
What is RHAG2?
OIa antigen
Low frequency
What is RHAG3?
DSLK antigen
Stands for Duclos like antigen
Reacts like Duclos but proven unique
What is RHAG4?
Low freqency
Only one case and caused HDFN
Person was African
What is f antigen?
RH6
Anti-f reacts with c in cis to e or Ro and r cells
65% of Caucasians
92% of Blacks - R0 and r very common
What is Ce antigen?
RH7 also known as rhi
most immune anti-C is in Rh positive is really anti-Ce
antibody reacts to C and e in cis position or R1 and r’ cells
68% of whites - R1 is most common
27% of blacks
What is Cw antigen?
RH8 weak C W stands for Willis Low freq present in 2% of whites, 1% of blacks, 4% finns, and 9% latvans Antithetical to Cx and Mars Most Cw cells are C+
What is Cx antigen?
RH9
Weak C
Very low frequency 0.01% (seen in 1.8% Finns)
Antithetical to Cw
What is RH39?
C-Like
Antibody reacts stronger C+ cells than C-
Antibody can be absorbed by C+ and C- cells except Rh null cells
What is RH51?
MAR antigen
High prevalence to Cw and Cx
100% are positive except 0.2% of Finns are MAR neg
What is RH2?
C antigen 4.2
Partial C = Cw, Cx, D(C)(e) and (C)ce^s
Anti-C in blacks may be anti-hrB (RH31)
68% Whites and 27% of blacks C +
What is RH3?
E antigen 4.3
Some examples of Anti-E are naturally occurring
29% of Whites and 22% of Blacks E+
What is R11?
Ew
Partial antigen detected by some but not all anti-E reagents
0.01% (Germany)
What is RH4?
c antigen 4.4
Most clinically sig next to D antigen
80% of Whites and 98% of blacks are c+
What is RH26?
c like antibody
antibody reacted with some c+ but not all cells
c+ RH26- cells found in Italians and Dutch
What is RH5
e antigen 4.5
Antigen for e has many parts - not full understood
Allo anti-e seen in e variants (missing e epitopes)
What are the two categories of partial e?
Partial e that make anti-e like antibody
Partial e and partial Hro (RH17) that make antibody that reacts with cells except Rh null
What is hr^s?
RH19 Present in 98% R2R2 cells are negative Negative seen in Africans (1% of Bantus) make anti-Hr Appears to be anti-e in e positive people
What is hr^b?
RH31
High frequency
Anti-e antibody in e positive person
Weak anti-hr^b may look like anti-C in blacks. Reacts stronger with C+ cells
Anti-hr^s and anti-hr^b are found in DIII people
Common in sickle cell patients
What is V?
RH10
ce^s
c is cis to e^s
30% of blacks are postitive
What is VS?
RH20 e^s Found in 32% of blacks Most V+ are VS+ hr^b neg cells are VS+
What is the rG haplotype>
rG cells have not DCE antigens but G is present
Assoc with JAHK
What is RH18?
Hr antigen
High freq present on all except RHCE null, Rh null and Hrs negative
What are the high prevalent Rh antigens?
Hr^o, Hr, hr^s, RH29 (total), hr^B, Hr^b, NOU, SEC, DAV, MAR
What are the low prevalent Rh antigens?
Dw, Goa, RH32, RH33 (DHAR), TAR, FPTT, BARC, DAK, Crawford
What is LW5?
LWa - 97%
What is LW6?
LWab - 3%
What is LW7?
LWb - Rare
What causes LW(a-b-) phenotype?
Rh null will type as LW(a-b-) even if LW gene is present
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
How do you transfuse a person with Anti-LW?
D neg RBC have less LW and survive well
What subclass is Anti-D most commonly?
IgG1 and IgG3
What does a weak anti-hrb resemble?
Anti-hrb will react stronger with C+ cells so may appear to be anti-C. May also appear as anti-Ce Occurs in black population.
How do you identify anti-hrs?
e like antibody in e+ people
To correctly identify anti-hrs, you must have cells that are cells that are e+ hrs-.
DFR
Type of partial D that is positive for FPTT (RH50)
DBT
Type of D-CE hybrid that is found in blacks
R^N (RH32) +
Normal D with weak C and e
Can make anti-SEC (RH46; high freq)
What partial/weak D’s will be detected?
III, IV, VII will type as D+ (3+4=7)
Variable results with DVI, DBT, DHAR, and Crawford
DVI will type neg at IS per FDA requirements
