FS2) Serology

Serology

The study of body fluids

Blood Transfusions

Directly outlawed in most countries in the early 1900’s, could lead to DEATH if the blood types doesn’t match

• Not only blood was transfused; then milk and saline

Blood Typing

Blood type system was determined by Karl Landsteiner (1901)

• A, A, AB, O

Antigen

Substance that INDUCES the formation of antibodies because it’s recognized to the immune system as a threat

• Produced by certain blood cells

• Could be naturally produced by ur body or extraneous threats

Antibody

Each antibody has their SPECIFIC antigen

• Destroy the antigen

• Enzyme “lock and key” kind of fit

Blood Type & Antigens

Specific blood types have specific kinds of antigens

• Blood Type O has NO ANTIGENS

Only people of the same blood TYPE can transfer blood

• AB blood can accept both A and B blood as they can recognize both

• TYPE O can only be given to type O; but O blood can be given to ANY OTHER BLOOD TYPE because they have no antigens to set of alarm bells

  • Universal Donor (O-)

Phenotype (blood type) & Genotype

A and B are dominant alleles

Type A

• AA or AO

Type B

• BB or BO

Type AB

• AB

Type O

• OO

Rhesus (Rh) factor

Discovered by Carl Lannstiner

Neither POSITIVE (have) or NEGATIVE (don’t have) this surface protein

• A POSITIVE receiver can take both ±, but a NEGATIVE can only take negative blood

Universal Donor & Acceptor

DONOR

O-

ACCEPTOR

AB+

Blood Type Percentages

Varies depending on demographic

RH Positive

O → 38%

A → 34%

B →9%

AB → 4%

Rh Negative

O → 6%

A → 6%

B → 2%

AB → 1%

(Forensics) Blood typing can be used to…

• Exclude a suspect

• Probability can be used to narrow down the search

Blood Factors

HUNDRENDS of characteristics of blood can be used to differentiate samples

What makes up blood?

Cells, enzymes, proteins, inorganic substances

• 55% plasma (erythrocytes)

• 45% cells (leuthryocytes)

Blood Type Antigens

Type A

Antibodies: B

• Has to KNOW what substance is foreign and should therefore kick out

Antigen: A

Type B

Antibodies: A

Antigen: B

Type AB

Antibodies: NONE

Antigen A & B

Type O

Antibodies: A & B

Antigens: NONE

Hemugglutination

Blood clots only form when the same antigen and antibody are added; the matching antibody would stick to the matching antigen

Testing Blood Stains

1) Is it actually blood?

• Luminol Test

• Percipitin Test

2) What species?

• Microscope

3) If human, how specific can we get with the blood?

Luminol Test

Tests whether a fluid is blood or semen (luminesces with both)

• Luminol and hydrogen peroxide need the catalyst (IRON) to shine

• No UV needed

Precipitin Test

Test tube with human-blood antibodies at the bottom

• WHen you add blood and a white layer forms, it means it is human blood

Non-Mammal

More ovular red blood cells with a visible nucleus

Mammal Blood cells

Circular red blood cells with NO nucleus

Secretor

Body secretes blood type antigens in ALL body fluids

• Makes up 80% of the population

Believed to be how mosquitos prefer secretors; O-blood is the most preferred, A the least, B in the middle

Blood Enzymes

Depending on the kind of enzyme, it could narrow down where the blood is from

A) Polymorphic

• Existing in MANY forms

B) Iso-Enzymes

Semen Test

A) Acid phosphatase color test

• If released, it turns PURPLE; indicates there is semen on the surface it was found

B) Florence Test & Barberio Test

• If result crystalizes, means there is sperm

C) Prostate Specific Antigen (PSA)

• Take antibodies that stick to this protein; if it’s present and sticks, it shows a positive reaction (2 lines, like a pregnancy test)

Saliva

Test for the enzyme amylase; look for nucleated epithelial cells with DNA

• If the person was a secretor, it could be used to determine their blood type

Size & Shape of Blood Drops

• Height of fal

• Angle of impact

• Surface on which the drops land

Calculating Angle of Blood Drops

Width/Length = arcsin(angle)