ABO Blood Group System

transfusion of incompatible blood is associated to what

acute intravascular hemolysis, renal failure, and death

transfusion of incompatible organs is associated to what

acute humoral rejection

which chromsome is the ABO gene on

chromsome 9

what are the four phenotypes resulting from the prescence or abscence of A or B antigen

A, B, O, and AB

what are the genotypes possible for the ABO blood groups

AA, AO, BB, BO, AB, and OO

which gene is the amorphic gene

the O gene because it has no detectable antigen

what structure commonly carries ABO and H antigens on the red blood cell membrane

a glycoprotein (carbphydrates attached to proteins)

where are ABO antigens found on

RBCs, PLTs, lymphocytes, most epithelial and endothelial cells and organs (kidneys, heart, bowel, pancreas, and lungs)

when do ABO antigens show up in the embryo

5-6 weeks into a pregnancy (gestation)

between what age group do you have adult levels of ABO antigens present

2-4 years old

when do the ABO antibodies start to develop

3-6 months of age, peak at 5-10 years old

are ABO antibodies present at birth

no (so you can’t do reverse blood typing on newborns)

are ABO antibodies naturally occurring

yes, they just develop after a few months after being born

what antibody does type A have on its RBCs

anti-B

what antibody does type B have on its RBCs

anti-A

what antibody does type AB have on its RBCs

no antibodies

what antibody does type O have on its RBCs

anti-A and B

what antibody does type A not have on its RBCs

anti-A

what antibody does type B not have on its RBCs

anti-B

what antibody does type AB not have on its RBCs

anti-A and B

what type of immunoglobulins are anti-A and B

IgM

what type of immunoglobulin are found in O patients

IgG and IgM

can ABO antibodies activate complement

yes (both IgM and IgG) at 37 degrees celsius

in group O, IgG individuals can also make

anti-A,B

which antibody can sometimes be found in people with subgroups of A

anti-A1

what temperature do ABO antibdoes react at

37 degrees celsius (room temp cold agglutinin)

what is the source of ABO antibodies

gut an environmental bacteria (enterobacteriaceae)

what antibody is not a combination of anti-A and anti-B but is a different “cross-reacting antibody” that is usually IgG

anti-A,B

what type of chains are the ABO blood group built on

two types of long chains, type I and type II

what are the three genes that modify the chains that ABO blood groups are built on

H gene on chromosome 19

Se chromosome 19

ABO gene on chromosome 9

another name for H gene

Fut 1 gene

another name for Se chromosome

Fut 2 gene

H, Se, and ABO genes produce what kind of enzyme

glycosyltransferases

glycosyltransferases add sugars to the precursors that make H, Se, and ABO, the sugars are known as

immunodominant sugars (responsible for RBCs being able to have their specific antigens)

what are the different types of glycosyltransferases

H(O)-antigen: alpha-2-L-fucosyltransferase

A-antigen: alpha-3-N-acetylgalactoseaminyltransferase

B-antigen: alpha-3-D-galactosesyltransferase

what are the three immunnodominant sugars

H(O)-antigen: L-fucose

A-antigen: N-acetyl-D-galactosamine

B-antigen: D-galactose

structure of H-antigen

formed for the platform on which A and B antigens are made

structure of A antigen

H antigen is the docking port that N-acetylgalactosamine can attach to

structure of B antigen

H antigen acts as a docking port that galactose can attach to

what antigen is the platform of A and B antigen

H antigen

what is the only antigen of the H blood group system

H

what are the two significant alleles of the H blood group system

H (dominant, 99.99% frequency)

h (amorph, rare frequency)

the H gene codes for

the glycosyltransferase L-fucosyltransferase to stimulate L-fucose to become a terminal sugar of type-1 or 2 chain

h is an amorph which means it has _______________________________

no detectable gene product

red cells from an hh individual are the ____________ phenotype

bombay

what immunodominant sugar encodes for the H anitgen

L-fucose

the Fut 1 gene results in which type of blood group

group O

which blood group has the highest concentration of H antigens

group O

which blood group has the least concentration of H antigen

A₁B

greatest to least amount of H antigen

type O > A₂ > B > A₂B > A₁ > A₁B

which type of chain is ABH antigens constructed on

type 2 chains (attached and a mixture of glycolipids/glycoproteins)

what is bombay

a rare autosomal recessive phenotype chracterized by the abscence of H, A, and B antigens on RBCs and in secretions

inheritence pattern of bombay phenotype

autosomal recessive

how does the bombay phenotype occur

a mutation in the H gene produces a silenced gene incapable of coding for H transferase

the bombay (O_h) phenotype typing looks like

O blood group but the serum contains anti-A, anti-B, anti-A,B, and anti-H

the bombay phenotype makes anti-H antibodies which can or cannot bind complement

can bind complement

if a patient had the bombay phenotype what kind of blood would they need

blood from another person that has the bombay blood type

how is para-bombay different from the bombay phenotype

it still results from genotype hh and at least one Se but has small amounts of A and/or B antigens on RBCs

since there’s H, A and/or B antigens in their secretions that get absorbed from plasma onto the RBC membrane resulting in weak expression

how is bombay detected

through absorption/elution studies

what antigens will a secretor carry

SeSe (carried by 80% of population

which gene encodes for mucosal protective functions and determines the ability to secrete your blood type antigen in body fluids and tissue

Fut 2

which antigen in plasma can absorb on platelets and lymphocytes but not on granulocytes and monocytes

A, B, and H antigen

in non-secretor how is the degree of protection decreased

IgA and IgG will be decreased in non-secretors, in addition to having decreased mucosal protective functions

expected reaction when preforming ABO typing on RBCs and plasma for phenotype A

anti-A: positive

anti-B: negative

A1 cells: negative

B cells: positive

expected reaction when preforming ABO typing on RBCs and plasma for phenotype B

anti-A: negative

anti-B: positive

A1 cells: positive

B cells: negative

expected reaction when preforming ABO typing on RBCs and plasma for phenotype AB

anti-A: positive

anti-B: postive

A1 cells: negative

B cells: negative

expected reaction when preforming ABO typing on RBCs and plasma for phenotype O

anti-A: negative

anti-B: negative

A1 cells: positive

B cells: positive

expected reaction when preforming ABO typing on RBCs and plasma for phenotype Oh (hh genotype with sese bombay)

anti-A: negative

anti-A: negative

A1 cells: positive (follow up with elution studies)

B cells: positive (follow up with elution studies)

expected reaction when preforming ABO typing on RBCs and plasma for phenotype Oh (hh genotype with at least one Se, para-bombay)

anti-A: negative

anti-B: negative

A1 cells: +/Ø

B cells: +/Ø

which subgroups are more common, A or B

A subgroups

which subgroup, A1 or A2 show increased reactivity with the anti-H

A1 reactivity is 80%

A2 is 20%

what A subgroups have the greatest amount of H antigen

A2

what would you use to distinguish the difference between subgroups A1 and A2

the lectin dolichos biflorus

chracteristics of the ABO subgroups

decreased number of antigen sites

variable agglutination with anti-A,B

variable detection of anti-H

anti-A₁ may or may not be present

infrequently encountered

dolichos biflorus lectin prefers what antigen

binds A1 and A1B

ulex europaeus lectin prefers what antigen

binds H and O cells

bandeiraea simplicifolia lectin prefers what antigen

binds B

vicia graminea lectin prefers what antigen

binds N

iberis amara lectin prefers what antigen

binds M

what are the two components of routine ABO typing

forward and reverse typing

type 1 chain

a free floating chain found in secretion (saliva, tears, urine, digestive fluid) as a glycoprotein

exist as glycolipids in plasma

type 1 chain structure

galactose connected with β 1-3 to N-acetylglucosamine and then a carbohydrate

type 2 chain characteristics

attached to the RBC membrane

a mixture of glycolipids/glycoproteins

type 2 chain structure

galactose connected with β 1-4 to N-acetylglucosamine and then a carnohydrate