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Forensic Serology
Chapter 8
Blood Components
 Plasma--fluid part of blood
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unclotted blood
Erythrocytes—hold
hemoglobin and transport
oxygen
Leukocytes—immune cells
Platelets--clotting
Serum—yellow fluid that
remains after clotting of
blood, mostly water +
dissolved substances
(proteins, ions, etc)
Antigen and Antibodies
 Blood Type A has A antigens and
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B antibodies
Blood Type B has B antigens and
A antibodies
Blood Type AB has both A and B
antigens and no antibodies
Blood Type O does not have any
antigens but both A and B
antibodies
Positive blood has Rh(D)
antigens = Rh+
Negative blood does not have
Rh(D) antigens but has D
antibodies = Rh-
Serology
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Positive blood will agglutinate with
Anti D serum
Negative blood will not agglutinate
with Anti D serum
A blood will agglutinate with Anti A
serum
B blood will agglutinate with Anti B
serum
AB blood will agglutinate with both
anti A and anti B serum
O blood will not agglutinate with
anti A or anti B
http://www.youtube.com/watch?v=
E0d5Qx42vmQ
Paternity Testing with Blood Type
 A Blood Type—AA or AO
 B Blood Type—BB or BO
 O Blood Type—OO
 AB Blood Type—AB
 Parent gives each offspring
one of two alleles
Immunoassay techniques
 Used to detect drugs in blood
and urine
 Animals are injected with
proteins with drug antigens—
animal makes drug detecting
antibodies that can be
harvested
 Presumptive drug testing with
these cultured antibodies can
be used to detect opiates,
cannabinoids, cocaine,
amphetamines, phencyclidine,
barbituates and methodone
Producing Antibodies
 Radioimmunoassay (RIA)—uses
radioactive tags to find drugs
 Enzyme-Multiplied
Immunoassay Technique
(EMIT)—fast and used with
urine; adds antibodies to urine
that bind to specific drugs
 Polyclonal and Monoclonal
Antibodies—animals produce
many different antibodies when
exposed is polyclonal; scientists
need one kind of antibody
(monoclonal; fused with cancer
cell to make hybridoma cell
Blood Stain Analysis
 3 Questions
 Is it blood?
 Is it human?
 Can it be matched closely to a
particular person?
Presumptive Color Testing
 Benzadine color test—use has
been reduced because it is a
carcinogen; measures for
presence of hemoglobin
 Kastle-Mayer—uses
phenolphthalein as an indicator,
and hydrogen peroxide to cause
the conversion of catalase to
give pink color; will test positive
with samples with catalase
(animal and some plant
material)
 http://www.youtube.com/watch
?v=6Ex0Fd_PDhU
Luminol
 Presumptive blood test
 Reaction with blood emits
light that can be seen in
darkened area
 Sprayed on area, turn dark,
emits blue light
 http://www.youtube.com/watc
h?v=hbEHvRrfqrc
Microcrystalline Tests
 Takayama test
 Teichmann tests
 Add chemicals to blood that
causes hemoglobin-containing
crystals to form
 Susceptible to contaminants
and less sensitive that color
tests
Precipitin Test
 Used to determine if blood
stain is human or from animal
 Grow antibodies to human
blood in rabbit; use antibodies
to test for presence of human
antigens; Human antiserum
 Rabbits can be used to make
antibodies against various
animal bloods as well
Gel Diffusion
 Use agar gel—antibodies and
antigens come together in
medium plate
 Blood and human antiserum
are loaded into wells
 Precipitant forms if blood is
human between two wells
Blood Spatter
 Important Blood Qualities to
Interpret Blood Spatter
 Surface texture—more spatter
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with softer, porous material
Direction of travel—pointed
end faces direction of travel
Impact angle—right angle
yields circular stain
Origin of spatter—draw lines
through many spatter points;
point of intersection is origin
of spatter
http://www.youtube.com/watc
h?v=Od8YuwUT794
Forensic Analysis of Semen
 Tests for Presence of Semen
 Acid Phosphatase Stain—acid
phosphatase is made by the
prostate gland and added to
semen during ejaculation;
presence can be detected by
acidic sodium alpha
napthylphosphate and fast blue
dye or 4-methyl umbelliferyl
phosphate (will fluoresce)
 Microscopic examination—look
for presence of sperm cells
 Prostate specific antigen—
polyclonal antibodies grown in
rabbits used to bind to p30
protein or prostate specific
antigen
Rape Evidence Collection
 Rape Kit Collection from
victims
 Hair samples: head, pubic,
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body
Body opening swabs: vagina,
anus, mouth
Blood sample
Fingernail scrapings
All clothing
Urine sample
 Collected from male suspects
 All clothing
 Hair: head, pubic, and body
 Genital swab
 Blood sample
 Cheek cells