The document describes the absorption-elution technique for blood typing dried blood samples in forensic analysis. The absorption-elution assay indirectly detects blood type antigens in dried samples by binding antigens to specific antibodies which are later eluted and tested for agglutination with blood cells of known types. This sensitive method allows identification of blood types in severely dried samples where direct testing is not possible. The absorption and later elution of antibodies based on their binding to antigens in the dried sample enables typing of old blood evidence through antibody identification.

1. • Submitted to:
Dr. Sapna Sharma
Asst. Professor
Dept of genetics
MDU Rohtak
• Submitted by:
Deepak Saini
M.Sc. Forensic sc. (F)
Rollno. -1602
Blood typing from
Absorption-elution
technique
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2. Introduction
• In 1923 Vittorio Siracusa was the first to use
the absorption-elution technique for the ABO
blood typing of blood stains.
• At crime scene, when there appear to spatters of dried blood,
investigators must follow a logical process in order to identify the
unknown substance.
• Whether material is blood or not?
• Whether it is of animal or not? Then it is of which animal species?
• Asuming sample is found to blood and blood is from animal that is human
the next task is to type the blood group.
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3. • The absorption_elution test ,published by
Vittorio Siracusa, has tremendous forensic
utility, because it can be used to identify old
and severly dried bloodstains.
• When the detemination has been made that a
particular stain contains human blood, but the
stain is extremly dry, an absorption-elution
test can be conducted.
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4. • The absorption-elution technique has been used
extensively to determine blood group from dried
stains, secretions, and teeth in various forensic
laboratories.
• This method is very sensitive, high specific, It also
has been found that the material once used is
available for re-use with practically no loss in its
antigenic properties.
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5. • ABO blood grouping system is most widely known and
medically important blood type because of its importance in
transfusion medicine. Its discovery goes back to 1900, when
Karl Landsteiner was trying to solve the mystery that some
blood transfusions are life-threatning while others are life-
saving. In 1930, he was crowned with Nobel Price for his
excellent discovery.
• The four basic ABO phenotypes are A,B, AB andO. Apart from
man, this system is also found in apes, gorillas and
chimpanzee.
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6. Importance in forensic biology
• In forensic science, blood typing is one of the
preliminary tests, which is done to exclude
some suspected sources of bloodstains.
Although this test doesn’t clearly indicate the
suspect involved because many people share
the same blood type.
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7. Methods of grouping
* In fluid blood samples, the presence or absence of an antigen
is ascertained by whether or not the red cells are
agglutinated. In dried bloodstains, the cells have ruptured and
direct agglutination tests are no longer feasible.
* However, the antigens are not immediately denatured upon
drying. In ABO system, they survive for many years and retain
capability of combining with specific antibody.
* The formation of these antigen-antibody complexes is the basis
of all methods employed in the detection of red cell antigens
in dried bloodstains.
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8. Absorption-elution assay
• The absorption-elusion assay is highly sensitive and
can be used for testing dried blood stains. It
indirectly detects the presence of antigens. The
successful agglutination reaction is usually require
intact cells. The agglutination reaction is, therefore
difficult to carry out because blood cells lyse when
they are dry. However, with this method , the lysed
cells containing antigen are immobilized on a solid
phase.
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9. Assay…..
• At lower temperature the
antigen is allowed to bind to
its corrensponding
antibody: anti-A antibodies,
anti-B antibodies or anti-O
lectins (which is isolated
from plants reacts strongly
with O antigen present in
type O blood)
• In fig. (A) Antigens are
immobilised on a solid
phase matrix.
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10. (b) Antibodies are added and absorbed.
( c) unbound antibodies are washed away.
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11. • The excess unbound antibodies are removed
by washing and bound antibodies are then
eluted at higher temperature ( recall that
antigen-Antibody binding can be affected by
temperature). This break antigen-antibody
bond, releasing anti-A antibody from surface
of fibre.
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12. • The eluted antibodies
can then be identified
by an agglutination
assay using A,B ,and O
indicator cells. (Or)
eluted antibody tested
with indicator cells
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13. The eluted antibody is identified by
positive agglutination reaction.
• Blood stain containing A antigen
can bind to anti-A antibodies. The
eluted anti-A antibody can form
agglutination with A cells.
Likewise for type B blood, eluted
anti-B antibody can form
agglutination. For type AB blood,
eluted antibodies can form
agglutination with both A& B
cells, with type O blood, eluted
antibodies can form agglutination
with O cells.
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14. • The typical results of an
absorption-elution
assay are summerized
in this table.
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15. Thank you,
Have a nice day
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