Blood Typing Basics
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BLOOD BANK ANTIGENS AND ANTIBODIES
Antigens are defined as substances recognized by the body as foreign, causing the body to
produce an antibody to react specifically with it. Antibodies are proteins produced by
lymphocytes as a result of stimulation by an antigen which can then interact specifically with
that particular antigen.
In order a substance to be an antigen to you it must be foreign (not found in the host):
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Autologous antigens are your own antigens (not foreign to you)
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Homologous, or allogenic, antigens are antigens from someone else (within the same
species) that are foreign to you
Blood group antigens:
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There are over 300 known blood group
antigens
Over 1,000,000 different antigen sites on
each red blood cell.
These antigens are attached to proteins or
lipids on the red cell membrane and are
usually complex sugar groups.
Some stick out far on the red cell
membrane and some are buried within
crypts on the membrane surface.
http://faculty.matcmadison.edu/mljensen/BloodBank/lectures/blood_bank_antigens_and_antibodi.htm
Rules of Thumb For in vivo Antigen-Antibody Reactions
1. If a person's cell have the antigen, the antibody should NOT be present in that person's
serum
2. If an antibody to a blood group antigen is present in the serum of a person, his or her
cells should lack that antigen
3. The antigens are on the cells and the antibodies are in the serum
Stages of Antigen-Antibody Interaction
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The first stage is sensitization. Sensitization occurs when antibodies react with antigens on the
cells and coat the cells
The second stage of the reaction is agglutination. Agglutination occurs when antibodies on
coated cells form cross-linkages between cells resulting in visible clumping.
BACKGROUND PART TWO:
BLOOD TYPING BASICS
Karl Landsteiner opened the doors for blood banking with his
discovery of the first human blood grouping system ABO, now also called
ABH. His discovery marked the beginning of the concept of a
person’s unique identity based upon the antigens present on the
membrane of the erythrocytes (RBC) membrane.
In 1901 Landsteiner drew blood from himself and five
associates, separated the cells from the serum, and then mixed
each cell sample with each serum. He was inadvertently the first
person to perform both the forward and reverse grouping.
The ABO group contains four blood types: A, B, AB, and O.
The letters A and B represent antigens on the red blood cell
membranes. A person with type A has A antigen on the RBC's, and someone with type B blood
has the B antigen. Type AB means that both A and B antigens are present, and type O means
that neither the A nor the B antigen is present.
http://pathmicro.med.sc.edu/mayer/rx-7.jpg
The frequency of these blood groups is as follows:
O positive
O negative
A positive
A negative
B positive
B negative
AB positive
AB negative
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38%
7%
34%
6%
9%
2%
3%
1%
ABO typing:
If your blood cells stick together when mixed with:
(Uses patient’s whole blood or RBC’s and antisera)
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Anti-A serum, you have type A blood
Anti-B serum, you have type B blood
Both anti-A and anti-B serums, you have type AB blood
If your blood cells do not stick together when anti-A and anti-B are added, you have type O
blood.
Reverse typing or back typing: (uses the patient’s serum and type A cells and/or type B Cells
from whole blood.
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http://i.dailymail.co.uk/i/pix/2008/06/21/article-1028274-01A7982200000578-632_468x344_popup.jpg
If the blood clumps together
only when B cells are added to your sample, you have type
A blood.
If the blood clumps together only when A cells are added to your sample, you have type
B blood.
If the blood clumps together when either types of cells are added to your sample, you
have type O blood.
Lack of blood cells sticking together when your sample is mixed with both types of blood
indicates you have type AB blood.
Source of Blood Typing antisera:
Monoclonal antibodies react with very specific antigenic
determinants. They are not produced in humans or animals, but harvested from cells in cells
grown in tissue culture. The tissue culture cells made from fusion of a plasma cell, which is the
antibody producer and the myeloma cell, which provides longevity and ability to make large
amounts of antibody
Lectins are sugar-binding proteins that are highly specific for their sugar recognition
affinities. They play a role in biological recognition phenomena involving cells and proteins.
Purified lectins are important in a clinical setting because they are used for identifying some of
the ABO(H) antigens. Some of the, (the prefix gyco refers to the presence of sugars) glycolipids
and glycoproteins on an individual's red blood cells can be identified by lectins. Lectins (a.k.a.
toxalbumins, phytotoxins, or phytohemagglutinins) were originally discovered in plants more
than a century ago by their ability to agglutinate (clot together) human red blood cells
(erthyrocytes). Some lectins are so specific in agglutinating certain blood types that they were
used in the characterizations of the human blood groups A, B, and O. The lectin is composed of
amino acids, and these proteins bind to sugar molecules of glycoproteins attached to the
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outside of blood cells, but they can also bind to glycoproteins on other cell types and to simple
sugars alone, such as sucrose.
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A lectin from Dolichos biflorus, (the Hyacinth bean), is used to identify cells that belong
to the A1 blood group.
A lectin from Ulex europaeus, (spiny evergreen shrubs) is used to identify the H blood
group antigen.
A lectin from Vicia graminea, (broad beans and vetch), is used to identify the N blood
group antigen.
RH typing:
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If your blood cells stick together when mixed with anti-Rh serum, you have type Rhpositive blood.
If your blood does not clot when mixed with anti-Rh serum, you have type Rh-negative
blood.
Blood types are based on specific antigens and antibodies related to RBC's. Specific blood
type antigens called agglutinogens are found in the cell membrane of erythrocytes. Antibodies
called agglutinins are in the plasma and are formed after birth. When agglutinins in the plasma
combine with agglutinogens on the surface of the RBC the result is agglutination or clumping of
the RBC's. The agglutinogens on the red blood cells are organized into groups. Although 30
groups are recognized, the ABO and the Rh are the most important. Blood type antigens on the
surface of the RBC's are agglutinogens. The antibodies in the plasma are called agglutinins.
The ABO grouping system is the only blood group system in which individuals will have
antibodies in their serum to antigens that are absent from their RBC. This occurs without any
exposure to RBC’s by transfusion or pregnancy. Due to the presence of these antibodies
transfusion of an incompatible ABO type can result in almost immediate lysis, (disintegration),
of the donor RBC’s. This produces a very severe, if not immediately fatal, transfusion reaction
in the patient.
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A patient's red blood cells can be mixed with antibody to a blood group antigen to determine a
person's blood type. In a second example, a patient's serum is mixed with red blood cells of a
known blood type to assay for the presence of antibodies to that blood type in the patient's
serum.
INHERITANCE OF BLOOD ANTIGENS
The theory for inheritance of the ABO blood groups was first described by Bernstein in
1924. He demonstrated that an individual inherits one ABO gene from each parent and these
two genes determine which ABO antigens are present on the membrane of the red blood cells,
(RBC’s). The ABO system like other blood systems is co-dominant in expression. One position or
locus on each chromosome 9 is occupied by an A, B, or O gene. In case of O allele, the exon 6,
(the sixth piece of active DNA in that chromosome) contains a deletion that results in a loss of
enzymatic activity. The deletion causes a frameshift and results in translation of an almost
entirely different protein that lacks enzymatic activity. This results in “H” antigen remaining
unchanged in case of O groups. So the O gene is considered an amorph (present but not
functional) because no antigen is produced in responsehttp://www.kinghawk828.com/en/up_files/xuexing1.jpg
to the inheritance of this gene.
The formation of the blood antigens results from the interaction of genes at three
separate loci, (ABO, Hh and Se). These genes do not actually code for production of antigens,
but for the production of specific enzymes which add sugars to a basic precursor substance that
is common to all of the blood types.
A, B, and H antigens develop as early as the 37th day of fetal life. The RBC’s of the
newborn have 25% to 50% fewer antigenic sites that those present on adult RBC’s and the
complete complement of these antigens will not develop until 2-4 years of age.
The H gene also located on
chromosome 9 is inherited by persons of all
blood types and codes for the production of
an enzyme that catalyzes the attachment of
sugars to the RBC’s cell membrane in
response to the A and B genes inherited as a
part of another locus on chromosome 9. So if
a person lacks the H substance even if they
have inherited the A and B genes it will
appear that they have type O blood because
the sugars that are synthesized and attached
to the basic precursor substance will not be
present and a blood test will indicate that the
person has type O blood (Bombay
Phenotype).
The “H” gene is present in 99.9 % of the random population. The allelic combination of
“Hh” is quite rare and “hh” is exceptionally rare with an inheritance rate of 1/8,000 in Taiwan,
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1/10,000 in India and 1/1,000,000,000 in Europe and the U.S. A patient who inherits the hh
combination of genes lacks the normal expression of any of the ABH antigens.
ABH antigens are an integral part of the membranes of RBC’s, endothelial cells,(The
endothelium is the thin layer of cells that line the interior surface of blood vessels, forming an
interface between circulating blood in the lumen and the rest of the vessel wall. Endothelial
cells line the entire circulatory system, from the heart to the smallest capillary), platelets,
responsible for blood clotting), lymphocytes,(white blood cells), and epithelial cells, (cover and
line body surfaces). ABH soluble antigens can also be found in all body secretions. Their
presence is dependent on the ABO genes inherited as well as the inheritance of another set of
genes on chromosome 9 called the secretor genes (Se or se). Eighty percent of the U.S.
populations are known as secretors because they have inherited one of the secretor genes. The
inheritance of the Se gene coded for the production of the A, B, and H antigens only in bodily
secretions and does not affect the production of ABH antigens on the RBC”s themselves.
The term “secretor” refers to the presence of A, B, and H substances in the body fluids,
and the presence of these substances does confirm the inheritance of an A, B, H, and Se gene in
an individual. In order to be a non-secretor the selected A, B, and H antigens are absent
because a person has inherited two copies of the “se” gene If a person is a secretor soluble A ,
B, and H antigens will be present in sweat, tears, saliva, and serum. When a blood test is
performed on a patient there are actually two separate test one uses antiserum to test for the
presence of the antigens on the surface of the RBC’s and a separate test to determine the
presence of the antigens in the serum.
Not all blood type antigens are inherited as a part of chromosome number 9. The “Rh”
antigen also called antigen “D” is inherited as a gene on chromosome number one. The
inheritance of this gene is considered by hematologists to be the most statistically significant of
the 30 blood antigens with the exception of the A, B, and H antigens. Antigen D is present if
85% of the random population while 15% of the population lacks the “D” antigen. In 1939 Philip
Levine and Rufus E. Stetson published their findings about a family who had a stillborn baby
who died of hemolytic disease of the newborn. The mother was aged 25 and it was her second
pregnancy and she suffered blood loss at the delivery. Both parents were blood group O and
the husband's blood was used to give the mother a blood transfusion, but the mother suffered
a severe transfusion reaction. They investigated this transfusion reaction. Since the mother and
the father were both blood group O, they concluded that there must be a previously
undiscovered blood group antigen that was present on the husband's RBCs but was not present
on the mother's RBCs and that the mother had formed antibodies against the new blood group
antigen. This suggested for the first time that a mother could make blood group antibodies
because of immune sensitization to her fetus's RBCs. They did not name this blood group
antigen, but it was subsequently found to be the Rhesus factor.
Additional genes near the “Rh” locus are the C, c, and E, e genes that are thought to
help regulate the expression the “Rh” antigens on the surface of RBC’s, and all must be tested
to determine the patients “Rh” phenotype.
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MEDICAL CONDITIONS RELATED TO SECRETED BLOOD TYPE
ANTIGENS
o If a person is a secretor, the presence of the
blood antigens will influence the populations
of bacteria capable of taking up residence in
the gastro-intestinal tract. This occurs because
some of the bacteria in the GI tract are
capable of producing enzymes that allow them
to degrade the terminal sugar of the A, B, and
H antigens and consume them as a food supply.
o ABH secretors have longer blood clotting times because they lack the necessary
concentrations of clotting factors
o Significant variations in carbohydrate concentrations in breast milk are found
between secretors and non-secretors.
o ABH non-secretors have a significantly higher number of duodenal and peptic
ulcers
o ABH non-secretors are at a higher risk for urinary tract infections
o ABH non-secretors are at higher risk for Neisseria meningitis
o ABH non-secretors are at higher risk for Candida albicans infections
o ABH non-secretors have a higher risk of dental caries
SO BLOOD TYPE CAN BE DETERMINED BASED ON THE PRESENCE OR ABSENCE OF
ANTIGENS AND ANTIBODIES IN WHOLE BLOOD, SERUM OR OTHER BODY FLUIDS AND
SOME TISSUES.
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THE CASE OF THE MISSING COLLEGE STUDENTS:
Aaron and Rebekah decided late on Wednesday night to take a weekend trip to
Crossville, TN to one of their favorite parks for a camping trip. They needed to relax before
their final exams began. Little did they know this would be the longest trip they would ever
take. Aaron and Rebekah were experience hikers and rafters in the Blue Ridge Mountains and
had worked several summers in Cumberland Mountain State Park that was just a few miles east
of Nashville.
The pair left the Vanderbilt campus early on Thursday morning with plans to return late
the following Sunday. They were up early and eager to get started. They stopped at the
convenience store across from Rebekah’s apartment to pick up last minute supplies and were
seen on the store’s security tapes at 4:35 a.m. smiling and holding hands. They had decided not
to call friends to tell them about the last minute trip, it was early and they had all been up late
studying.
When neither Rebekah nor Aaron was in class on Monday their friends were not too
concerned because it was not unusual for the pair to skip Monday classes. When neither of the
two was in classes all week, Rebekah’s roommate decided to call the police to report the couple
missing.
The authorities began an immediate search. This is when the police discovered the
convenience store video tape and they discovered a second video of the pair in Aaron’s SUV at
a freeway onramp for I 40 East. The timestamp on this video was 5:45 a.m. and corresponded
with the time that the couple had been seen at the store. The interviews with the couple’s
friends painted a picture of a happy couple who enjoyed spending their free time together
sharing their passion for hiking and camping. The police searched both of the student’s
apartments and discovered that their camping gear was missing. In subsequent interview
authorities discovered that the area where Rebekah and Aaron liked to camp was difficult
mountainous terrain, with a thick dense canopy of trees, dense undergrowth, and numerous
deep valleys and gorges. Aarons SUV was discovered by park rangers in a remote area behind
Byrd Lake in the Cumberland Mountain State Park. After a lengthy and extensive search, the
couple was never found.
More than a year later a group of hikers discovered two sets of
remains near an unused trail at the bottom of a deep gorge. The
remains were in an advanced state of decomposition. There was some
soft tissue still intact, but it was decomposed to the point where
ethnicity and gender were not immediately identifiable. There were no
clothes on the remains. The pelvis of each skeleton was absent, the long
bones were scattered and had obviously been gnawed on by
scavengers, and the marrow had been exposed to the elements. There
were obvious signs of foul play because only a few fragments of each
skull were located
Because of the lack of evidence, determination of gender will be difficult. The long
bones were used to estimate height of each of each of the sets of remains. Set two is estimated
to be approximately 6’2” and set number one is estimated to be 5’6”. These height estimations
are consistent with the heights of Rebekah and Aaron. The ethnicity of the remains was judged
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to be Caucasian based on the lack of curvature in each of the femoral shafts, which is also
consistent with the missing couple.
Based on this preliminary information, Police believed that the remains might be those
of the two missing students. But you must complete the analysis of the tissue samples in order
for the police to make a positive ID. Police are sure foul play is involved in the case because
remains of clothing were not located and the condition of the skull fragments indicated blunt
force trauma. There were also injuries on the femurs of both victims that had been made with a
wide sharp blade and that were inconsistent with the activity of predators.
Tissue samples were obtained and sent to you for analysis. Due to the advanced state of
decomposition, cyto-technicians have fixed some of the samples for you onto slides so that you
can more quickly complete your portion of the investigation.
Aaron’s blood type is AB and Rebekah’[s blood type is O
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