Lutheran Blood Group System Flashcards
Talk about the clinical significance of the lutheran blood group
The Lua antbiody is the main antibody we see
Lua is not clinically significant
The lub antibody is rarely seen but Lub is clinically significant
The Lu3 antibody is seen in the null state
Talk about the discovery of the Lutheran blood group
It was originally discoveed in a blood donor
It was the fifth discovered blood group
It is mispronounced -> Should be luth-er-an not lootheran but the name has stuck
Anti-Lua was discovered in 1945 in a serum that contained several other antibodies
Talk about the genetics of the lutheran system
It is a single locus system
It consists of 25 antigens
The genes of the Lutheran group are linked to the genes responsible for the secretion of ABH substances i.e. the Se gene on chromosome 19
The main antigens are Lua and Lub
The majoriity of antigens are purely academic and we dont see them in clinical setting
What is the function of the Lu blood group system?
It helps erythrocytes locate to stromal cells of bone marrow
Haematopoiesis will occur more distriubted in the body if you are missing the Lutheran antigen
It will occur outside of the bone marrow without lutheran
Talk about the lutheran antibodies
It has an IgM and IgG component
Anti-Lua was the first discovered antibody in 1945 in serum containing several other antibodies
i.e not high sensitisation rate
Talk about the frequency of the Lu antigens
Lu (a+b+) 7.5
Lu (a+b-) 0.15
Lu (a-b+) 92.35
Lu (a-b-) Very rare
NB: >99% are Lub+
How does Lua and Lub differ from each other?
There is a single base pair change difference
His 77 Arg
What is a good way of remembering the frequencing of the Lua antigen?
There is always one Lua positive cell in an antibody panel i.e. 1/12 cells
Lua frequency = 1/12 or approximately 8% (7.65% exactly)
Talk about the lutheran antibodies
igG/IgM
They are not enzyme sensitive
Not often encountered especially anti-Lub
There is often variation in Lu antigen strength
Crossmatch compatible blood issues
What is the other important antigens of the Lu system?
Auberger antigens:
Au(a) = 80% of population
Au(b) = 50% of population
What are the telltale signs of anti-lutheran antibodies?
They tend to give clear reactions in gels - normal reactions
Tend to give scruffy reactions in tubes - these dont look like aggregation, looks more like clotting, looked different under the mic as well
Scientist often able to do this - how they used to be identified - characteristic clumping
Talk about anti-Lua
IgM and IgG (mostly IgM though)
Usually not clinically significant in transfusion but mild cases of HDFN have been reported (igG type)
Anti-Lua may be present without immune red cell stimulation
Optimal in vitro agglutination reactions are observed at room temperature but gives a characteristic mixed-field/scruffy pattern of agglutination
Why does Lua not cause clinically significant reactions?
There are very few copies of the antigen on the red cells - only a few thousand copies
Talk about anti-Lub
Rare antibody due to the high incidence of Lub >99%
IgG class
Most anti-Lubs agglutinate at the antiglobulin phase but some examples of Lub show a mixed-field agglutination pattern
Anti-Lub has been associated with transfusion reactions and mild cases of HDFN
Fabian has never seen an anti-Lub
Why does Lua cause mixed-field reactions?
Small agglutinates are surrounded by unagglutinated free red cells
Few antigens on red cells
