Chapter 8
Blood
“Out damned spot! Out, I say
Here’s the smell of the blood still,
All the perfumed of Arabia will not
Sweeten this little hand. Oh, Oh, Oh!”
—William Shakespeare’s Lady Macbeth, in Macbeth
Blood
You will learn:
 That an antibody and
an antigen of different
types will agglutinate,
or clump, when mixed
together.
 That the significance of
the evidence depends
on a characteristic’s
relative occurrence in
the population.
Blood
You will be able to:
 Determine whether a
stain is blood.
 Determine whether a
bloodstain is human or
animal blood.
 Determine the blood
type of a simulated
bloodstain using the
ABO/Rh system.
Serology
The examination and analysis of body fluids
From 1950’s to 1980’s -- high importance
With DNA -- now a matter of economics
Blood Characteristics



Plasma is the fluid portion of the
blood (55%)
Cells (45%)
 Erythrocytes are red blood
cells. They are responsible for
oxygen distribution.
 Leukocytes are the white blood
cells; they are responsible for
“cleaning” the system of
foreign invaders.
 Platelets (proteins) are
responsible for blood clotting
Serum is the liquid that separates
from the blood when a clot is
formed.
Parts of Blood
Unknown Stain at a Scene
Questions to be answered:
 Is it blood?
 Is it human blood?
 Whose is it?
 Determine blood type, alcohol
content, drugs present
 Determine the method(s) in
which blood may have been
deposited
Presumptive Tests for
Blood Determination
 Kastle-Meyer color test—a mixture of
phenolphthalein and hydrogen peroxide; the
hemoglobin will cause the formation of a deep pink
color if blood is present
 Hematest® tablet—reacts with the heme group in
blood causing a blue-green color
 Luminol test—reaction with blood to produce light
Testing for Blood
 Both the Kastle Meyer and Luminol test for
presence of blood are examples of chemical
reactions.
Human vs Animal Blood
 Microscopic observation
 Precipitin test—blood is injected into a rabbit;
antibodies are formed; the rabbit’s blood is
extracted as an antiserum; the antiserum is
placed on sample blood. The sample will react
with human proteins, if human blood is present.
This test is very sensitive and requires only a
small amount of blood.
Animal Blood
Larger nucleic red
blood cells
Frog Blood
Human Blood
 Red blood cells are most
numerous; 5 to 6 million
per mm3
 White blood cells are
larger and less numerous;
5 to 10,000 per mm3
 Platelets are tiny, cellular
fragments; 350 to 500,00
per mm3
Secretors
80% of the population are secretors.
Their blood-type antigens are found in
high concentration in their body fluids
such as saliva, semen, vaginal
secretions and gastric juice.
Historical Perspective
of Blood Typing
Karl Landsteiner
1900
4 types
In 1940 Rh factor
85% of Caucasions
94% Black Americans
99% Asians
How is our blood type determined?
 Your blood type is established before you are
BORN, by specific GENES inherited from
your parents.
 You receive one gene from your MOTHER
and one from your FATHER.
 These two genes determine your blood type by
causing proteins called AGGLUTINOGENS
to exist on the surface of all of your red blood
cells.
Blood Typing
 A-B-O and Rh systems are the most important in
identifying blood
 An individual that is type A has A antigens on
his/her red blood cells
 Type B has B antigens
 Type AB has both A and B antigens
 Type O has neither A nor B antigens
Agglutination
 For every antigen there is a specific
antibody that will react with it to form
clumps (agglutination)
 For example, Red blood cells containing B
antigens will react in the presence of B
antibodies
What are blood types?
There are 3 alleles or genes for blood
type: A, B, & O. Since we have 2 genes,
there are 6 possible combinations.
How common are the 4
blood types?
Blood Types
AA or AO = Type A
BB or BO = Type B
OO = Type O
AB = Type AB
4%
11%
45%
40%
http://www.lanecountyblood.org/images/other/bloodfacts.jpg
http://learn.genetics.utah.edu/units/basics/blood/types.cfm
Blood Groups
Antibody Can Give
Can Get
Blood From
Type
Antigen
A
A
B
A, AB
O, A
B
B
A
B, AB
O,B
AB
A and B
Neither
A nor B
AB
A, B, O, AB
O
Neither
A nor B
A and B
A, B, O, AB
O
Blood To
Rh Factors
 Scientists sometimes study Rhesus monkeys to learn
more about the human anatomy because there are
certain similarities between the two species. While
studying Rhesus monkeys, a certain blood protein was
discovered. This protein is also present in the blood of
some people. Other people, however, do not have the
protein.
 The presence of the protein, or lack of it, is referred to
as the Rh (for Rhesus) factor.
 If your blood does contain the protein, your blood is
said to be Rh positive (Rh+). If your blood does not
contain the protein, your blood is said to be Rh
negative (Rh-).
http://www.fi.edu/biosci/blood/rh.html
A+ AB+ BAB+ ABO+ O-
Rh factor
 Determined by presence of another antigen
 People having antigen are Rh +
 People not having are Rh-
Blood Typing
To determine a person’s
blood type, we add three
different serums to blood
samples and see if clumps
form.
Clumps = Positive (+)
No Clumps = Negative (-)
Use the results shown to
determine the blood type
for each sample.
+ = Clump
- = No Clumps
A
Rh
What would the blood type
be for this sample?
B
Blood Type: ___
A
Blood Typing
A
Rh
Use the results shown to determine the
blood type for each sample.
B
Rh
B
Blood Type: ___
+ = present
A
A
Rh
- = absent
B
A
Rh
B
Blood Type: ___
Blood Type: ___
Rh
B
Blood Type: ___
Blood Type: ___