Lecture 1: Characteristics & Testing Of Blood

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Terence Norton
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1 Lecture 1: Characteristics & Testing Of Blood

2 Blood Physiology: Composition of Blood Plasma (55% of the mix) is the fluid portion of the blood. Cells (45% of the mix ) Red Blood Cells are responsible for oxygen distribution. White Blood Cells are responsible for launching an immune response to foreign substances. Platelets are responsible for platelets forming. Serum (5% of the mix) is the liquid that separates from the blood when a clot is formed.

3 Historical Background On Blood Typing Around 1900, Karl Landsteiner discovered that there are four different types of human blood based on the presence or absence of specific antigens found on the surface of the red blood cells. In 1940, Landsteiner and Weiner reported the discovery of the Rh factor by studying the blood of the Rhesus monkey. 85% of Caucasians, 94% of Black Americans and 99% of all Asians are Rh positive.

4 Blood Terminology: ABO blood groups based on having an A, B, both or no antigens on red blood cells Rh factor may be present on red blood cells; positive if present and negative if not Antigen a substance that can stimulate the body to make antibodies. Certain antigens (proteins) found in the plasma of the red blood cell s membrane account for blood type. Antibody a substance that reacts with an antigen Agglutination clumping of red blood cells; will result if blood types with different antigens are mixed.

5 What is blood type? There are 3 alleles or genes for blood type: A, B, & O. Since we have 2 genes, there are 6 possible combinations.

6 Blood Typing Blood type A has antigen A on the surface of the cell and will agglutinate with blood type B. Blood type B has antigen B on the surface of the cell and will agglutinate with blood type A. Blood type AB has antigens A and B on the surface of the cells and will NOT agglutinate with either type A or B blood. Blood type O has NEITHER antigen A or B and will agglutinate with blood types A, B, and AB.

7 How is blood type determined? Your blood type is established before you are BORN, by specific GENES inherited from your parents. These two genes - one gene from your MOTHER and one from your FATHER determine your blood type by causing proteins called AGGLUTINOGENS to exist on the surface of all of your red blood cells.

RH Factors Scientists sometimes study Rhesus monkeys. There are certain similarities between the humans and monkeys. While studying Rhesus monkeys, a certain blood protein was discovered.

8 RH Factors Scientists sometimes study Rhesus monkeys. There are certain similarities between the humans and monkeys. While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein. The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor. If your blood does contain the protein, your blood is said to be Rh positive (Rh+). If your blood does NOT contain the protein, your blood is said to be Rh negative (Rh-).

9 In Animal Blood. Larger nuclear red blood cells Red blood cells are most numerous; 5 to 6 million per mm 3 White blood cells are larger and less numerous; 5 to 10,000 per mm 3 Platelets are tiny, cellular fragments; 350 to 500,00 per mm 3 as compared to human blood.

10 Microscope Views Bird Blood Dog Blood Snake Blood Fish Blood Human Blood

11 Testing For Blood Presumptive blood tests: 1 st test Can tell us that the sample is most likely blood. NOT A FACT though. Inexpensive, quick, & easy to do (in the field) Confirmatory Blood Tests: 2 nd step Tells us FOR SURE whether or not the sample is blood. Time-consuming & more expensive

12 Types of Presumptive Blood Test Kastle-Meyer Test Color change test Phenolphthalein + hemoglobin + H 2 O 2 = pink color change Hemoglobin causes the H 2 O 2 to react with the phenolphthalein STEPS?? False positive? TMB Test Color change test Phenolphthalein + hemoglobin + H 2 O 2 = pink color change Hemoglobin causes the H 2 O 2 to react with the phenolphthalein STEPS?? False positive?

13 Types of Presumptive Test LMG Color change test LMG = leucomalachite green STEPS?? Hematrace Test Color change test Different than other tests because it can be used on dif. samples clothes that have been washed STEPS?

14 Types of Presumptive Test Luminol Test Fluorescing test Very sensitive Can detect ~ 1/10 million parts Can show blood in areas that have been cleaned (w/o bleach) or painted over Luminol + H2O2 + Fe in blood= glow STEPS?? Fluorescing Test Fluorescing test sticks better than luminol (thicker) NOT affected by bleach STEPS?

15 Types Of Confirmatory Test Use blood typing & DNA analysis tests Crystalline test = chemical reagent + hemoglobin = crystal formation Works well w/ OLDER stains (cold cases)

Biological Evidence: Goals

Biological Evidence: Goals 1. Identify a stain/tissue 2. Identify species of origin - is it human? 3. Individualize it i.e. get a DNA profile? 4. Compare it to a known sample Serology and DNA Profiling