Other Blood Group Systems Flashcards
What are the four other most important blood group systems?
MNS
Kel
Duffy
Kidd
Why are MNS, kel, Duffy and Kidd important blood groups?
(4)
All react at 37 degrees
All cause HDN
All have IgG
All cause transfusion reactions
Who found the MNS Blood Group System?
Landsteiner and Levine
How did Landsteiner and Levine find the MNS blood group system
Experiments with immunised rabbits
Remained a simple two allele M and N system for 20 years
Who found the S antigen and when
In 1947 the S antigen was defined by a new antibody by Montgomery and Walsh
This was followed by the antithetical antigen-s in 1951 by Levine et al
What do we know about the genetics of MNS?
Both sets of genes are closely linked on Chromosome 4
Where is MNS expressed?
(3)
The antigens reside on the major redd cell Glycophorins - GPA and GPB
M and N are found on GPA
S and s are found on GPB
How does M differ from N?
Differs by 2 amino acids
How does S differ from s
A single amino acid change
Why are MN and S considered the same blood group
(2)
Right beside each other genetically
Therefore they are probably the duplication of a single gene
Comment about MN antibodies
(3)
Anti-M and anti-N are typical ‘cold agglutinins’
They are IgM
They rarely cause HTR or HDNB
Comment about Anti-S or anti-s antibodies
Associated with HTR and HDN
What does is mean if a patient is M+, N-, S+ and s+?
MM homozygous for Glycophorin A i.e. all Glycophorin A will be M type
Glycophorin B will be 50% S and 50% s
Comment on MNS in serology
MNS antigens susceptible to enzyme degradation
Proteolytic enzymes used in blood group serology include Papain, Bromelin, Ficin and their main effect is to reduce the ‘repulsive forces between rbcs”
Who found the Kell Blood Group System and when
Lancet, Coombs, Mourant and Race first defined the antigen in 1946 by an antibody in the serum of a Mrs. Kellacher
Write about the Mrs. Kellacher serum antibody. (Kell antibody)
This antibody reacted with the red blood cells of her husband, a daughter and her newborn
Also reacted with 9% of a random population antigen called K (K1)
When was the allelic partner of K1 found?
In 1949 it’s allelic partner and corresponding antigen-k (K2), discovered
K and k antigens are antithetical, what does this mean?
Directly opposed or contrasted, mutually incompatible
Write about the Kell Blood group
(6)
Antigens are expressed on a red cell bound glycoprotein
K and k are antithetical
Well developed at birth
The K antigen is very immunogenic (second to the D antigen) in stimulating antibody production)
Many examples of Anti-K are found in transfused persons and multiparous women
We give K- blood to all women of childbearing years
Comment on the genetics of the Kell System
Genes located on chromosome 7
Need to have KK to produce anti-k -> only 0.2% of the population
99.8% of people have a k, 91% are kk and 8.8% are Kk
What is a k person called
Cellano
Write about anti Kell antibodies
(4)
Usually IgG in nature
Active at 37 degrees Celsius
Cause HTR and HDNB
Require the antiglobulin (Coombs) test for their demonstration in vitro
What might cause anti-K production in non-transfused children?
Bacterial infections e.g. E. Coli and S. faecium
What is the Duffy (Fy) Blood Group System?
(3)
Cytokine receptor
Duffy antigen cleans up cytokines
In biochemistry known as Duffy associated receptor for cytokines -> DARC
How was the Duffy blood group discovered?
(4)
In 1950 the antibody to Fya was seen in a multi-transfused haemophiliac - Mr. Duffy
In 1951 the antithetical antibody and antigen was found - anti-Fyb
In 1955 it was realised that many black populations lacked Duffy antigens (Fya-b-)
There are also Fy3, 4, 5, 6, but these do not feature in routine transfusion testing - extremely rare
Why do 75% of black populations lack Duffy antigens
(2)
The duffy antigen is the site where malaria gets into red blood cells
By natural selection those who lacked duffy where protected against malaria in high risk regions of Africa
Comment of the genetics of Blood Group Systems
(3)
Found on chromosome 1
First antigen to be mapped
Single amino acid difference between Fya and Fyb
Comment on the trends in Duffy antigen expression
(5)
49% are Fy(a+, b+)
34% are Fy(a-, b+)
17% are Fy(a+, b-)
Fy(a-, b-) is rare in white but high in black populations
Most people who are sickle cell are Fy(a-, b-)
Very few donations are Fy(a-, b-) which are needed for sickle cell transfusions
Fy(a-b-) gives resistance against which malaria causing parasite
(3)
Plasmodium knowlesi -> also P. vivax
Invasion site for P. knowlesi is the Fy6 antigen
Fy6 is absent on Fy(a-, b-) cells
How does malaria interact with Duffy antigens
Antigens act as receptors for the merozoite to attach to the red blood cell
Comment on the Duffy antigens
(4)
Well developed at birth
Destroyed by enzymes
Fya and Fyb
Codominant alleles
Comment on the Duffy antigens
(4)
Well developed at birth
Destroyed by enzymes
Fya and Fyb
Codominant alleles
Comment on Duffy antibodies
(6)
Implicated with HTR and HDN (rare)
IgG
Sometimes complement dependent - activate the pathway to C3 stage
Stimulated by transfusion or pregnancy (not common cause of NDFN)
Don’t react with enzyme-treated RBCs
Require antiglobulin test for demonstrate invitro
Antigen deterioration can cause subsequent detection problems in the lab
How was the Kidd (Jk) blood group discovered?
(3)
Discovered in 1951 as a result of HDN in the 6th child born to a Mrs. Kidd - Jka -> John Kidd
in 1953 anti-Jkb found in a transfused reaction patient
Kidd antibodies usually found in combination with other antibodies and are notorious for delayed, secondary, transfusion reactions i.e. found in reactive patients
List the most common Kidd antigens in whites
50% = Jk (a+b+)
27% = Jk (a+b-)
23% = jk (a-b-)
Double negative rare especially in polynesian
What are the most common kidd antigens in blacks
51% = Jk (a+b-)
41% = Jk (a+b+)
8.8% = Jk (a-b-)
Double negative very rare
What exactly are the Kidd antigens?
Urea transporters
Comment on the Kidd Antibodies
(6)
Require the IAT for their demonstration in vitro
Responsible for approximately 30% of DHTRs
Antigen deterioration and/or dosage possible a contributing factor
Enhanced by enzymes
Partially IgM/IgG -> can activate complement to cause significant haemolysis
HDN rare but Kidd antigens found on foetal cells at 11 weeks pregnant
