Serology Forensics - 2017

Components of Blood Plasma – fluid portion of blood (55%) Cell (45%)

Plasma

Blood Cells Erythrocytes – Red blood cells Carry oxygen through the body Leukocytes – White blood cells Cleans the blood of “foreign invaders” Thrombocytes – Platelets Responsible for blood clotting

Red Blood Cells

White Blood Cells

Platelets

Blood Clots

Serum Liquid that separates from the blood when a clot is formed

Blood Questions to be answered: Is it blood? Is it human blood? Whose is it?

Presumptive Tests for Blood Kastle-Meyer color test - phenolphthalein and hydrogen peroxide are mixed together the blood’s hemoglobin will cause the formation of a deep pink color Leucomalachite test - leucomalachite green mixed with acetic acid and distilled water; then a drop of sodium perborate will turn blood green and then darken. Tetramethylbenzidine (TMB) – a possible blood stain is sampled with a moistened cotton swab and applied to a Hemastix containing TMB causing the strip to turn blue-green.

Presumptive Tests for Blood – Fluorescence Luminol test - reaction with blood results in the production of light Fluorescein – used to find stains that have been cleaned with chlorine bleach

Confirmatory Tests Microcrystalline tests--add specific chemicals to the blood in order to form characteristic crystals Work well with older stains Takayama Teichmann

Human vs Animal Blood Precipitin test blood is injected into a rabbit anti-human antibodies are formed precipitin line forms if sample is human blood

Blood Groups Can Give Blood To: Can Get Blood From Type Antigen Antibody A A B A, AB O, A B, AB O , B B B A Neither A nor B AB A and B AB A, B, O, AB Neither A nor B O A and B A, B, O, AB O

Blood Type and Genetics IA and IB are dominant over i If there is a IA or IB, it will override the lower case “i” Using a Punnett Square, you can determine what an offspring’s blood type could be.

The Genetics of Blood Type Type A – IA IA or IA i Type B – IB IB or IB i Type AB – IA IB Type O – i i

Rhesus or Rh Factor Also known as the D antigen If the antigen is present, the blood is positive. If the antigen isn’t present, the blood is negative.

Blood Reactions to Antiserum Anti-A Serum Anti-B Serum BLOOD TYPE Agglutination No agglutination No agglutination Agglutination Type A Type B Type AB Type O

Population Distribution of Blood Types in the U. S. Percent O 45 A 39 B 12 AB 4