Duffy Flashcards
DUFFY BLOOD GROUP SYSTEM (_____)
ISBT#
008
The Duffy blood group system was discovered in____ when a multi-transfused hemophiliac patient named_____ was found to have an antibody in his serum, which was later identified as_____.
The following year (____), another antibody,_____, was identified in the serum of a woman who had undergone three pregnancies.
1950
Mr. Duffy
anti-Fya
1951
anti-Fyb
One of the major clinical significances of the Duffy system is its association with_____, as the_____ is recognized as the entry point for this parasite into red blood cells (RBCs).
Plasmodium vivax malaria
Fy6 epitope
The absence of_________ in many individuals of West African descent confers resistance to P. vivax infection, making the _____phenotype an important evolutionary adaptation in malaria-endemic regions.
Fya and Fyb antigens (Fy[a−b−])
The Duffy blood group antigens are encoded by the Duffy___ gene, located on____
(FY)
chromosome 1
Phenotype
Fy(a+ b-)
Fy(a- b+)
Fy(a- b-)
Genes/ Antigens????
Fy^a
Fy^b
Fy
Antigens
Fy^a
Fy^b
Fy
Phenotypes???
Fy(a+ b-)
Fy(a- b+)
Fy(a- b-)
DUFFY ANTIGEN
● Identified on fetal red cells at____ weeks gestation
6
Duffy Ag
T or F???
● Well developed at birth
True
Duffy Ag
● ONLY FOUND ON
RED CELLS (in blood cells)
○ Not found on lymphocytes, monocytes etc.
Duffy Ag
● Identified to be found in other body tissues:
➢ Brain
➢ Spleen
➢ Colon
➢ Thyroid
➢ Endothelium
➢ Thymus
➢ Lung
➢ Kidney cells
● FyA & FyB Are destroyed by common proteolytic enzymes:
○ Ficin
○ Papain
○ Bromelin
○ Chymotrypsin
○ ZZAP
Duffy Ag
Not affected by..
AEP (a-chymotrypsin at acidic pH)
Glycine acid EDTA
Phenotype???
Antigen Expression
Antibody Reaction Strength
High expression of Fya
Strong reaction with anti-Fya antibodies
Fy(a+ba-)
Phenotype???
Antigen Expression
Antibody Reaction Strength
High expression of Fyb
Strong reaction with anti-Fyb antibodies
Fy(a-b+)
Phenotype???
Antigen Expression
Antibody Reaction Strength
Moderate expression of both Fya and Fyb
Weaker reaction compared to homozygous individuals
Fy(a+b+)
Phenotype???
Antigen Expression
Antibody Reaction Strength
No Duffy antigen expression on RBCs
No reaction with anti-Fya or anti-Fyb antibodies
Fy(a-b-)
Duffy blood type more common in whites
Fy (a+b+)
Duffy blood type more common in blacks
Fy (a-b-)
Antigenic determinant that is common to BOTH Fya and Fyb antigens
Fy3
Common to Blacks
Fy4
Result of interaction between Rh complex and Duffy glycoprotein;
unknown molecular structure
Fy5
Used by Plasmodium vivax as a receptor to gain entry in the RBC
Fy6
Inherited weak form of Fyb
Fx
Unaffected by enzyme treatment
Fy345
Affected by enzyme treatment
Fy6x
The Duffy antibodies are predominantly____, which means they are____-reacting antibodies that react best at___C and are detected at the AHG (antihuman globulin) phase of testing.
IgG; warm; 37°C
DUFFY ANTIBODIES
● IgG (majority)
○ Highly reactive at_____
○ Increases strength with____
AHG phase
LISS(potentiator)
Dosage Effect
Stronger reaction in homozygous individuals (Fy[a+b-] or Fy[a-b+]); weaker in heterozygous individuals.
• In white populations, most individuals are_____, so their antibody reactions may be weaker.
• In Black populations, many individuals are____, which means they lack Duffy antigens completely and do not form anti-Fya or anti-Fyb naturally.
heterozygous Fy(a+b+)
Fy(a−b−)
are receptors for malaria parasite
■ Used Plasmodium knowlesi for study
● P . vivax cannot be cultured
○ Fya and Fyb
2 types of receptors required for malarial parasites to
enter RBC:
■________- Duffy independent
■________- Fy6 antigen
Attachment receptor
Invasion receptor
