Other blood group systems Flashcards
Kell Blood group system antigens & frequency
32 antigens: Cellano/K2 - 99.8% Kell/K1- 9% Kpa & Kpb - b is more common Jsa & Jsb - b is more common
Kell Blood Group system general
only expressed in RBCs & RBC precursors
preseent on fetal RBC
integral membrane protein w/ a high degree of di-sulfide intramolecular bonds
Reducing agents that will destroy Kell antigens
2-mercaptoethanol (2-ME) or dithiothreitol (DTT)
Antigenicity of Kell antigens
K antigen most immunogenic after ABO, D
associated w/ hemolytic transfusion reactions
Characteristics of Kell Antibodies
IgG class
does NOT bind complement
enzymes show no enhancement/depression of reactivity
Depressed activity w/ LISS reagents
K0 phenotyp
lack of the KEL gene
produce an antibody (anti-Ku) against Kell antigen
rare but clinically relevant
KX blood group system
KX is a carrier protein for Kell that brings it to the membrane & stabilizes it
people lacking KX have low levels of Kell antigen & form anti-KX antibody
KX & Kell genetic interaction
Genetically independent from the Kell system
if XK1 gene is not inherited, Kx antigen is not expressed & Kell antigens will not be stabilized in the RBC membrane
McLeod syndrome
reduced expression of Kell antigens
individuals have red cells w/ morphological & functional abnormalities
X linked disorder CGD (chronic granulomatous disease) -ingest but do not destroy bacteria
high bacterial infections
acanthocytes
Duffy Blood group summary
Fy (shortcut), clinical significance
IgG (37C), AHG
Enzymes destroy the antigen!
Duffy blood group antigens general characteristics
antigen’s present on birth, only on RBC, not strong immunogens
Fya & Fyb are antithetical
Fy3 antigen-epitope common to all duffy proteins
Duffy blood antigen statistics in White populations
Fy(a+b+), Fy(a+,b-), Fy(a-,b-)
Duffy blood antigen statistics in black populations
Fy(a-,b-) & FyES ( erythroid silent)
Duffy blood group system biochemistry
duffy encodes a protein called DARC, spans membrane 7x & is a G-protein coupled receptor!
binds several chemotactic cytokines
Duffy blood group genetics
Fya & Fyb are codominant alleles
FyES -recessive; Fy(a-,b-), gene promoter deletion
Duffy blood group system & malaria
duffy is a receptor for Plasmodium vivax & P. knowlesi
individuals lacking duffy Ag are 100% resistance to P. vivax & knowlesi (susceptible to falciparum though)
large portion of the black population
Clinical relevance of duffy antibodies
antibody production is stimulated by transfusion / pregnancy - HDN
can lead to delayed hemolytic transfusion reactions
anti-Fya is 20x more likely to lead to a transfusion reaction
Anti-Fy3 antibody
duffy antibody that reacts with both Fy(a+) & Fy(b+)
resistant to enzymes
similar to antiA,B antibodies
Characteristics of duffy antibodies
IgG antibody, does NOT bind complement
enzymes degrade the antigens
show dosage!
Kidd Blood group system summary
shortcut- JK clinically significant IgG antibody class (37) AHG enzymes enhance reactions
Kidd blood group system antigens
3: JKa, JKb, JK3
JKa & JKb are antithetical
JK3 is present when either JKa or JKb antigens are present
entirely protein, present on cells at birth, not very immunogenic
Kidd blood group genotype statistics
JK(a-,b-) found in Chinese, Filipino, & Polynesian populations
Kidd blood group biochemistry
gene encoding Kidd antigen: SLC14 (solute carrier 14) - urea transporter
can easily screen for JK(a-,b-) units by Urea experiment = these cells are resistant to hemolysis in urea
Kidd antibodies
anti-JK3 reacts w/ any JKa or JKb positive cell
IgG titer is low!! shows dosage
antibody is unstable in vivo & in vitro!!!!
WILL BIND COMPLEMENT!!!
all potentiators will enhance reactions
Clinical relevance of Kidd Antibodies
mild HDN
responsible for the majority of delayed hemolytic transfusion reactions!! (#1 cause)
titer rapidly increases in 24 hr period, BINDS COMPLEMENT
Lutheran blood group system summary
shortcut- LU
Lua - clinically significant, IgG & IgM
Lub - not clinically significant
Lutheran blood group system general characteristics
most are high-frequency antigens aka alloantibodies to this system are infrequently found (!)
antigen destroyed by DTT treatment
Lutheran Antigens
LU1 (Lua), LU2 (Lub)
not present at birth
LUb - very high frequency
LUa- low frequency