Other Blood Groups Flashcards
What is the structure of CO antigens?
Multipass - pass membrane 7x
located on aquaporin-1 (AQP1)
Also called CHIP-28 channel forming integral protein
It is a water channel that is responsible for 80% of the water that is reabsorbed in the kidneys
What antigens are present in Colton (CO) BGS?
Coa and Cob are co dominant (Coa = High)
Co3 and Co4 are high freq. present when colton antigens are present >0.01% is Co(a-b-)
What are characteristics of the Colton antigens?
Present on cord cells = mild/severe HDFN
Not destroyed by DTT or enzymes
Poor immunogens - few Colton antibodies seen
Weak typing seen in In(Lu) phenotype
What is Co null?
Co(a-b-) Caused by silencing of CO gene Cells are Co:(-a,-b,-4,-5) Co-3 = no aquaporin and may have serious electrolyte and metabolic disorder when dehydrated Co-4 = have functional aquaporin
What are the characteristics of Co antibodies?
IgG; reacts are IAT Have been implicated in HTR and HDFN May bind complement Cob - found w/ other antibodies (XM comp; 8% Cob+) Coa require rare antigen neg units
How do you antigen type for Coa?
No antisera available.
Molecular typing can be preformed
What chromosome is Xg located on?
Chromosome X
Xga and CD99 escape x inactivation
What antigens are present in Xg BGS?
Xg1 = Xga on RBC’s
Xg2 = CD99 a high prevelance antigen that is also present on fibroblast and lymph nodes
Phenotype is either Xga- or Xga+
How is Xga inhierted?
Xga is X linked dominate - occurs in females more often
Males will be hemizygous if inherit from mother and will pass Xga to all daughters
What % of females and males are Xga positive?
66% of males are Xga positive
90% of females are Xga positive
What are the characteristics of Xga antigen
Sensitive to enzymes
Resistant to DTT
Poor immunogen
What are the characteristics of anti-Xga?
IgG reacts at IAT
immune stimulated
May see MF due to low density of antigens on the RBC’s
What is lyonization?
In females, a random X chromosome is inactivated early in somatic cell developement.
Once a x chromosome is inactivated all cells from that clonal will have the same X inactivation
Xga escapes lyonization= no dual population of RBC
What is the gene name for Diego BGS?
DI or SCL4A1
What is the gene product for DI?
Band 3 (anion exchanger 1)
What is structure/function of Diego antigens?
Diego is a multipass glycoprotein on band 3
Makes up 20% of membrane protein
Band 3 transports anions of bicarb and Chloride across the cell membrane and allow CO2 to enter
Band 3 is achnored the membrane by ankyrin and protein 4.2
What disease is associated with lack of band 3?
Mutation in band 3 results in SE Asian ovalucyctosis, hereditary spheocyctosis, and some acantocytosis
What are the High frequency DI antigens?
Dib, Wrb, and DISK
Di(a-b+) = most common
What are the characteristics of Dia antigens?
Present on Cord cells
Can cause HDFN
Resistant to Ficin and DTT
What is frequency of Dia?
Very low freq. in Caucasians
Present in Mongolian populations
50% of S American Indians
12% of Asians
What are the characteristics of DI antibodies?
IgG1 and IgG3
Can cause HDFN
Immune stimulated (one naturally occur. anti-Dia)
What is prevelance of Wra and Wrb antigens?
Wra is low frequency
Wrb is 100% frequency
Where is Wrb antigen located on?
It is on AE-1 in close association with GPA
GPA is required for Wrb expression
GPA neg and MkMk individuals lack Wrb
What are the characteristics of Wra antibodies?
IgG and IgM
Can be naturally occur. Found in 2% of un-transfused males and seen in pregnant women
Often seen with other antibodies or warm auto’s
Relatively common
Can cause HTR and HDFN