Protien-based Blood Group Antigens II Flashcards
Weak D phenotype can be cause by…
Inheritance of a D gene that codes for decreased expression
or
Inheritance of C gene on the chromosome opposite the D gene (Ceppellini effect)
Partial D can be caused by…
Inheritance of a D gene that does not encode all of the epitopes present on the D antigen
The McLeod phenotype is characterized by:
Acanthocytes, compensated hemolytic anemia with reticulocytes, increased LDH, decreased haptoglobin, hypersplenism, decreased expression of Kell system antigens, increased creatinine kinase MM isoenzymes, progressive neurological changes
What is the genetic reason for the McLeod phenotype?
The genes for Duchene muscular dystrophy, retinitis pigmentosa and CGD are closely associated with the XK gene.
Describe the K0 (Kell null) phenotype
It is associated with complete lack of Kell system antigens but the Kx protein is markedly increased in expression and individuals do not have features of McLeod phenotype.
What antibodies can individuals with CGD and the McLeod phenotype produce?
Anti-Kx and anti-Km
What antibodies can individuals with McLeod phenotype without CGD produce?
Anti-Km
What makes high titer low avidity antibodies behave the way they do?
Reactivity is causes by a very high titer antibody and low number of antigens on the red cell surface.
Why is anti-JMH seen in older individuals?
The JMH antigen can be lost after age 50 and in such settings, anti-JMH can occur.
What is unusual about anti-Pr?
The antibody is usually a cold reacting antibody and the Pr antigen is destroyed by enzyme treatment. On the other hand autoantibodies, warm- and cold-reactive antibodies are typically enhanced with enzyme treatment.
Interesting facts about Sda antigen and anti-Sda:
Sda antigen is present on Tamm-Horsfall glycoproteins in urine and excreted in urine of Sda positive individuals. All guinea pigs are positive for Sda. Expression may be decreased during pregnancy (similar to LW and Le).
Characteristic finding of anti-Sda is orange refractile agglutinates in field of unagglutinated red cells.
What appearance do antibodies to Lutheran blood group system antigens (Lua, Lub) cause when the antigen is present?
Mixed field appearance
Facts about LW antigen:
Has a reactivity pattern that mimics RhD, is not destroyed by enzymes but destroyed by DTT, strongly expressed on fetal cells (even RhD neg).
What molecules contain the vast majority (>90%) of a red cells sialic acid?
Glycophorin molecules (A, B, C, D)
