Serology

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Serology

• Chapter 12

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Serology

• It is the study of body fluids
• Blood
• Saliva
• Semen
• Urine

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Functions of Blood

• Blood has 3 main functions
• Transportation
• Oxygen, carbon dioxide, wastes, nutrients, heat,
  hormones
• Regulation
• Ph, body temperature, water content
• Protection
• From disease loss of blood

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Characteristics of Blood

• Thicker than H2O and flows more slowly
• 100.4 F temp
• Ph of 7.4
• 8 of body weight
• Blood volume
• Male- 5-6 liters
• Female- 4-5 liters

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Components of Blood

• Blood consists of
• 55 plasma
• 45 cells
• 99 RBC (red blood cells)
• lt1 WBC (white blood cells) and platelets

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Plasma

• 90 H2O
• 7 plasma proteins
• Albumin- maintain blood osmotic pressure
• Globulin- form antigen- antibody complexes
• Fibrinogen- for clotting
• 3 other substances
• Electrolytes, nutrients, hormones, gases, waste
  products

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Formed Elements of Blood

• Red blood cells (erythrocytes)
• White blood cells (leukocytes)
• Platelets (thrombocytes)
• Serum

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Formation of Blood Cells

• Blood cells need to be replaced continuously
• Die within hours, days, or weeks
• Process is called hematopoiesis
• In embryo, occurs in yolk sac, liver, spleen,
  thymus, lymph nodes, red bone marrow
• In adult- occurs in red bone marrow of sternum,
  ribs, skull, pelvis

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Red Blood Cells (RBC)

• Contains hemoglobin (carries oxygen)
• Gives it its red color
• Makes up 1/3 of cells weight
• Is biconcave
• Increased savol
• Flexible for narrow passages
• No nucleus or organelles (no cell division)
• In adult
• Male- 5.4 million RBC/gttp (drop)
• Female- 4.8 million RBC/gttp

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White Blood Cells (WBC)

• Are leukocytes
• Have a nucleus and no hemoglobin
• Classified as granular or agranular based on
  presence of granules in the cytoplasm
• Granulocytes- neutrophils, eosinophils, basophils
• Agranulocytes- monocytes, lymphocytes

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Platelets

• Disc shaped
• No nucleus present
• Normal count
• 150000- 400000 gttp/blood
• Other blood cell counts
• 5 million RBC
• 5-10000 WBC

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Serum

• Is the liquid that separates from the blood when
  a clot is formed

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Immunoassay Techniques

• Are available for detecting drugs through
  antigen-antibody reactions
• 2 types of processes
• EMIT (enzyme multiplied immunoassay technique)
• Antibodies that bind to a specific drug are added
  to a subjects urine
• RIA (radioimmunoassay)
• Uses drugs labeled with radioactive tags

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Antigen-Antibody Reactions

• When an animal is injected with an antigen, its
  body will produce a series of different
  antibodies, all of which are designed to attack
  some particular site on the antigen of interest
• Called polyclonal antibodies
• Antibodies designed to combine with a single
  antigen site can be manufactured
• Called monoclonal antibodies

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Forensics of Blood

• The criminalist must be prepared to answer the
  following questions when examining dried blood
• Is it blood?
• From what species did the blood originate?
• If the blood is of human origin, how closely can
  it be associated to a particular individual
• Detection of blood is best made by means of a
  preliminary color test

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Presumptive Tests for Blood Determination

• 3 tests
• Kastle-Meyer color test
• Is a mixture of phenolphthalein and hydrogen
  peroxide
• Hemoglobin of blood will cause a deep pink color
  if blood is present
• Hematest tablet
• Reacts with the heme group in blood causing a
  blue-green color
• Luminol test
• Reacts with blood to produce light

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Human vs. Animal Blood

• Once the stain has been characterized as blood,
  the precipitin test will determine whether the
  stain is of human or animal origin
• Uses antisera normally derived from rabbits that
  have injected with the blood of a known animal to
  determine the species origin of a questioned
  bloodstain
• Once the bloodstain has been determined to be of
  human origin, the blood is typed

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The Discovery of Blood Types

• Before Landsteiners discovery, countless people
  died from blood transfusions
• There was an assumption back then that everybody
  had the same blood
• In 1900, Landsteiner proved that there are four
  different types of blood based on the presence or
  absence of specific antigens on the surface of
  RBCs
• Known as ABO blood group
• In 1940, he discovered the Rh factor

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Blood Types

• RBC surfaces are marked by genetically determined
  glycoproteins glycolipids
• Agglutinogens or antigens
• Distinguishes at least 24 different blood types
• Most common ABO RH

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ABO Blood Groups

• Based on 2 glycolipid antigens (A B) found on
  the surfaces of RBC
• Antigen A only type A blood
• Antigen B only type B blood
• Both antigens type AB blood
• No antigens type O blood
• Plasma contains antibodies or agglutinins to the
  A or B antigens not found in your blood
• Anti- A antibody reacts with antigen A
• Anti-B antibody reacts with antigen B

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Breakdown of ABO Blood Types

• Type A- 42
• Type B- 12
• Type AB- 3
• Type O- 43

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Rh Factor

• Antigen was discovered in rhesus monkey
• Called Rh antigen or D antigen
• People with Rh agglutogens on RBC surface are Rh
  (normal plasma contains no anti-Rh antibodies)
• Antibodies develop only in Rh- blood type only
  with exposure to the antigen

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Breakdown of Rh Blood Type

• Rh- 85
• Rh- - 15
• Of the Rh population, 85 are Caucasians, 94
  are African Americans, and 99 are Asians

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Universal Donors and Recipients

• People with type AB blood are called universal
  recipients
• No antibodies present
• Can receive blood from anybody
• People with type O blood are called universal
  donors
• No antigens present
• Can donate blood to anybody

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Typing and Cross Matching of Blood

• Mixing of incompatible blood causes agglutination
  (visible clumping)
• Formation of antigen- antibody complex that
  sticks cells together
• Not the same as blood clotting
• Typing involves testing blood with known antisera
  that contains antibodies A, B, or Rh
• Cross matching is to test by mixing donor cells
  with recipients serum
• Screening is to test recipients serum against
  known RBCs having known antigens

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ABO vs. DNA

• Prior to the advent of DNA typing, bloodstains
  were linked to a source by ABO bloodtyping
• DNA analysis has allowed forensic scientists to
  associated blood and semen stains to a single
  individual

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Blood Spatter Evidence

• It is a field of forensic investigation which
  deals with the physical properties of blood and
  the patterns produced under different conditions
  as a result of various forces being applied to
  the blood
• Follows the laws of physics

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Blood Pattern Reconstruction

• What to look for at the crime scene
• Stain condition
• Pattern
• Distribution
• Location
• Directionality

• What you get from blood evidence
• Genetic marker typing
• Age determination
• Source determination
• Race determination
• Sex determination

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Blood Spatter

• CSIs must remember the location, distribution,
  and appearance of bloodstains and spatters
• Useful in interpreting and reconstructing the
  events that produced the bleeding
• Surface texture and the stains shape, size, and
  locating must be considered when determining the
  direction, dropping distance, and the angle of
  impact of a bloodstain

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Blood Droplet Characteristics

• A blood droplet will remain spherical in space
  until it collides with a surface
• Once a blood droplet impacts a surface, a
  bloodstain is formed
• A droplet falling from the same height, hitting
  the same surface at the same angle, will produce
  a stain with the same basic shape

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Blood Droplet Volume

• A droplet contains approximately 0.05 mL of fluid
• It is not the same for all blood droplets, but is
  generally between 0.03 mL to 0.15 mL
• Is directly dependent upon the surface or orifice
  from which it originates
• The impact area is called the target

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Conditions Affecting Shape of Blood Droplet

• Size of the droplet
• Angle of impact
• Velocity at which the blood droplet left its
  origin
• Height
• Texture on target surface
• On clean glass or plastic
• Droplet will have smooth outside edges
• On a rough surface
• Will produce scalloping on the edges

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Questions Answered by Blood Spatter Interpretation

• The distance between the target surface and the
  origin of blood
• The point(s) of origin of the blood
• Movement and direction of a person or an object
• The number of blows, shots, etc causing the
  bloodshed and/or the dispersal of blood
• Type and direction of impact that produced the
  bloodshed
• The position of the victim and/or object during
  bloodshed
• Movement of the victim and/or object after
  bloodshed

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Bloodstain Terminology

• Parent drop
• The droplet from which a satellite spatter
  originates.
• Satellite spatters
• Small drops of blood that break off from the
  parent spatter when the blood droplet hits a
  surface
• Spines
• Pointed edges that radiate out from the spatter

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Bloodstain Terminology

• Angle of impact
• Angle at which blood strikes a target surface
• Bloodstain transfer
• When a bloody object comes in contact with a
  surface and leaves a patterned blood image on the
  surface
• Backspatter
• Blood that is directed back toward the source of
  energy

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Bloodstain Terminology

• Cast off
• Blood that is thrown from an object in motion
• Directionality
• Relates to the direction a drop of blood traveled
  in space from its point of origin

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Bloodstain Terminology

• Contact stain
• Bloodstains caused by contact between a wet
  blood-bearing surface and a second surface which
  may or may not have blood on it
• 3 types
• Transfer
• An image is recognizable and may be identifiable
  with a particular object
• Swipe
• Wet blood is transferred to a surface which did
  not have blood on it
• Wipe
• A non-blood bearing object moves through a wet
  bloodstain, altering the appearance of the
  original stain

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Bloodstain Terminology

• Terminal velocity
• It is the greatest speed to which a free falling
  drop of blood can accelerate in air
• Is dependent on the acceleration of gravity and
  the friction of the air against the blood- 25.1
  ft/sec
• 3 types
• High velocity- greater than 25 ft/sec, usually
  100 ft/sec gives a fine mist appearance
• Medium velocity- 5-25 ft/sec
• Low velocity- 5 ft/sec or less

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Bloodstain Patterns

• Round
• If it falls straight down at a 90 degree angle
• Elliptical
• Blood droplet elongates as the angle decreases
  from 90 to 0 degrees
• Angle can be determined by the following formula
• Impact angle sin-1 (arcsin) x (width/length)

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Impact

• The more acute the angle of impact, the more
  elongated the stain
• 90 degree angles are perfectly round drops with
  80 degree angles taking on a more elliptical
  shape
• At about 30 degrees, the stain will begin to
  produce a tail
• The more acute the angle, the easier it is to
  determine the direction of travel

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Bloodstain Patterns

• The harder and less porous the surface, the less
  the blood drop will break apart
• The softer and more porous the surface, the more
  a blood drop will break apart
• The pointed end of the blood stain faces the
  direction of travel

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Area of Intersection and Convergence

• The location of the blood source can be
  determined by drawing lines from various blood
  droplets to the point where they intersect
• The area of convergence is the point of origin
• The spot where the blow occurred

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Blood Evidence

• Class evidence for blood would include blood type
• If you can determine the DNA, you would have
  individual characteristics
• Blood stain patterns are considered
  circumstantial evidence in a court room
• Experts could argue many points including
  direction of travel, height of the perpetrator,
  position of the victim, left/right hand, whether
  the body was moved, etc