Blood Grouping, Serum and Plasma By Elkhedir Elgorashi, MLT, M Sc.
Blood grouping dr. rafiq
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Transcript of Blood grouping dr. rafiq
Blood Grouping
DR. RAFIQ AHMAD
ABO & Rh(D) Blood Groups
The ABO System
Discovered in 1901 by Dr. Karl Landsteiner
4 Main Phenotypes (O, A, B, AB,) ABO gene located on long arm of
chromosome 9
- ABO, Hh, Sese
The ABO Antigens
Added to Proteins or Lipids in Red Cells Substrate Molecule is H (fucose) A antigen is N-acetyl-galactosamine (GalNAc) B antigen is Galactose (Gal) A and B genes code for transferase enzymes
Blood group (or blood type)
ABO group Biochemistry
ABO Sub groups
ABO Antibodies Antibodies produced to “non-self” Produced after first few months of life A & B people have mainly IgM O people have IgG May fade in old age
A: A1, A2, A3, Ax, Am, Ael …, A(B)B: B3, Bx, Bm…, B(A)
Inheritance of ABO Groups
Allele from the mother
Allele from the father
Genotype ofoffspring
Blood types ofoffspring
A A AA A
A B AB AB
A O AO A
B A AB AB
B B BB B
B O BO B
O O OO O
Distribution of ABO Groups
PopulationO A B AB
Aborigines 61 39 0 0 Basques 51 44 4 1 Blackfoot (N. Am. Indian) 17 82 0 1 Saudies (Eastern Province) 49 27 19 5 Chinese-Canton 46 23 25 6 Chinese-Peking 29 27 32 13 English 47 42 8 3 Hawaiians 37 61 2 1 Irish 52 35 10 3 Mayas 98 1 1 1 Navajo (N. Am. Indian) 73 27 0 0 Peru (Indians) 100 0 0 0 United Kingdom (GB) 47 42 8 3 USA (blacks) 49 27 20 4 USA (whites) 45 40 11 4
Distribution of the A allele
Distribution of the B Allele
Distribution of the O Allele
ABO Typing
Cell Group Test Washed Cells With: Monoclonal Anti-A Monoclonal Anti-B Inert control
Agglutination is a positive result
Reverse Group Test plasma/serum with: Known A1 cells Known B cells Known O cells ? Known A2 cells
Reactions may be weaker than cell group
Significance of ABO Group
ABO mismatched transfusions: Rare May be life threatening Can be caused by technical or clerical error Intravascular haemolysis More severe in group O patients
Universal Donor and Recipient
Universal Donor Group O
Carries no A or B antigens
Packed and processed units have little antibody
Universal Recipient Group AB
Patient has no anti-A or anti-B present
Cannot lyse any transfused cells
Beware: other
antibodies may be present
Patient’s own group should always be preferred
The Rh(D) Antigen
Rh is the most complex system, with over 56 antigens
Discovered in 1940 after work on Rhesus monkeys
Subsequently discovered to be unrelated to monkeys
Rh gene located on short arm of chromosome 1
In mid 1940’s other Rh antigens C, c, E, and e were discovered
Simple Genetics of Rh(D)
97% of asians are Rh(D) pos The antithetical antigen d has not been found The d gene is recessive:
Dd, dD, DD, persons are Rh(D) pos Only dd persons are Rh(D) neg
Distribution of Rh(D) Types
Population Rh(D) pos Rh(D) neg
Caucasian(Saudis), E Pro.
86%(90.5)
14%(9.5)
African-American 95% 5%
Oriental >99% <1%
Significance of Rh(D)
80% of Rh(D) neg persons exposed to Rh(D) pos blood will develop anti-D
Anti-D can also be stimulated by pregnancy with an Rh(D) positive baby Sensitisation can be prevented by the use of anti-D
immunoglobulin, antenatally and post natally
Rh(D) neg females of childbearing potential should never be given Rh(D) positive blood products
Inheritance
ABO & Rh genes are not linked ABO & Rh(D) type are inherited independently
For example:An A Rh(D) pos mother
and a B Rh(D) pos father
could have an O Rh(D) neg child
Rh Typing
Routine Rh typing
for donors and
patients involves
typing for only the
D antigen.
D Testing
Routine D antigen testing involves testing the patient RBCs with anti-D commercial antisera
If the D antigen is present, it should agglutinate strongly with anti-D at Immediate Spin (IS) If you’re Rh+, you have the D antigen If you’re Rh-, you do not have the D antigen
Weak D phenotype
Some D-positive RBCs DO NOT react at Immediate Spin using commercial anti-D
In these cases, AHG testing is needed to determine the D status
Weak D testing
If negative at IS, patient cells and anti-D reagent are incubated at 37° for 20 minutes, then centrifuge
If still negative, wash x3 and add AHG If negative, add CC and report as Rh negative (if CC
agglutinate) If positive, report as Weak D Positive
Patients who require AHG testing to determine the presence of the D
antigen are called “Weak D Positive”
Weak D (Du) Phenotype
Weak D can be inherited in three ways: Incomplete/Partial antigen (D mosaic) Due to the position effect Weakened expression of D
Partial D (D Mosaic)
Missing one or more parts of the D antigen Since the antisera is specific for the whole D
antigen, a weak reaction may result if patient has a partial antigen
Why is Partial D is significant? If the patient is transfused with D positive red
cells, they may develop an anti-D alloantibody* to the part of the antigen (epitope) that is missing
* alloantibody- antibody produced with specificity other than self
Position Effect
Gene interaction effect C allele is in trans position to D allele Does not occur when C is in cis position Steric hindrance causes the anti-D reagent to
weakly attach (C antigen crowds the D antigen)
Inheritance of ABO and Rh(D)
Mother
Group A AO
Rh(D) pos Dd
Father
Group B BO
Rh(D) pos Dd
Group A AO
Rh(D) pos Dd
Group B BO
Rh(D) pos Dd
Group O OO
Rh(D) neg dd
AABB Standards
Require weak D testing on all donor red blood cells that do not agglutinate at IS
DO NOT require weak D testing on recipient blood each facility has their own protocol If only IS is performed and patient is negative, they will
receive negative units However, some labs don’t like to waste D-negative units, so
they take the test to AHG If the patient is positive, they may receive D-positive units
(it would be rare that the patient is a Partial D)
The end!!
Thank you