Serology Composition and Testing Quiz

RSID Test Pros and Cons

Con: Requires a relatively large amount of sample (0.1 mg of hemoglobin) Pro: Test results can be completed within 10 minutes Pro: The test does not interact with any other human body fluids or animal blood samples.

Many Types of WBCs

Either granular or agranular

Platelets (thrombocytes)

-Each drop of blood contains 250,000 to 500,000 platelets. -Irregular shaped and sticky, they are responsible for clogging up wounds so we do not lose essential blood when we cut ourselves. -Hemophiliacs lack Factor VIII (blood clotting protein) -A clot begins to form when blood comes into contact with air. -Platelets begin to break apart into small fragments and react with fibrinogen (a glycoprotein) to form fibrin. -Fibrin and platelets form a trap of threads that capture more platelets and cells, and these develop into a scab after they harden. -Warfarin and aspirin interfere with the reaction -Platelets and Fibrin hold back RBCs

Luminol Precautions

-False positives can occur with: -copper salts, brass, bronze and similar alloys -Important to consider when dealing with locks, door handles and other fixtures made of these materials -Household bleach -Some vegetables

White Blood Cells (Leukocytes)

-Have nuclei (containing DNA) and mitochondria. -You normally have 4,000-11,000 WBCs in a drop of blood. -Why are they important? -Fight infections (from the common cold to HIV) -Prevent the growth of cancer -When you have an infection, the number of WBCs increases, like more soldiers are needed during a battle!

How do Presumptive Tests for Blood Work

-In general, these tests rely on hemoglobin's (protein found in red blood cells) ability to catalyze the oxidation of certain reagents. -This usually results in a color change -Hydrogen peroxide is usually the oxidizing agent

Agranular WBCs

-Lymphocyte Second most common (24%) Form from stem cells B type made in bone and produce antibodies T type made in thymus and produce helper and killer cells. -Monocyte Largest blood cell (15-25µm in diameter) Develop into macrophages

Granular WBCs

-Neutrophil - most abundant (70%); many-lobed nucleus -Eosinophil - 2 lobed nucleus; rare (1-6% of WBC); react to histamine; granules stain red -Basophil - most rare; S-shaped nucleus; granules stain blue; produce histamine

What is blood made of?

-Plasma -Red Blood Cells (erythrocytes) -White Blood Cells (leukocytes) -Platelets

RSID Test for Human Blood

-The test uses two specialized antibodies to detect the presence of human Glycophorin A (a protein) that is found in red blood cell membranes -The antibodies are applied to the suspected sample using a strip test assay -Certain markings will appear to indicate whether human blood was detected or if the test failed.

ABO Blood Types

-There are four phenotypes for blood; A, B, AB, and O. -How do the blood types differ? -There are two types of antigens (A and B) that can be present on the red blood cell (surface makers). -There are two types of antibodies (A and B) in the plasma. Antibodies are proteins used to counteract and recognize a foreign substance. -There are four possible combinations that make up the four blood types.

HemaTrace Test Precautions

-This test will cross react with some animal blood -Primates and ferrets -Positive results can be obtained in other body fluids other than blood if trace amounts of hemoglobin are in other body fluids -Insufficient sample quality or quantity could impact results

Luminol

-Used on invisible stains -Luminol is a chemical compound. It is usually mixed with hydrogen peroxide to create a solution. The solution is sprayed onto suspected areas. -Luminol reacts with hematin, a substance formed as bloodstains age. -Luminescence is observed if blood is present. -Lasts only a few minutes- so pictures are taken to use as evidence. -Aged bloodstains tend to give more intense and long-lasting luminescence -Area can be resprayed to view again.

Kastle-Meyer test

-Used on visible stains -A phenolphthalein solution is added to the blood stain, followed by hydrogen peroxide. -A bright pink color change indicates the presence of blood. -Can produce a false positive when used on saliva, pus, malt and vegetable extracts, and salts of certain metals.

Hemastix

-Used on visible stains -Detects the presence of hemoglobin -Compare the color on the strip to the color on the bottle. -Cannot distinguish between human and animal blood.

HemaTrace Test

-Used to detect human blood by identifying the presence of human hemoglobin (a protein that carries oxygen). -Test strip contains anti-human hemoglobin antibody. -The State Crime Lab considers this a back up test if the RSID test is not available.

Alternate Light Sources

-Used to view potential evidence that is not visible with the naked eye -Uses monochromatic light sources (light of one specific wavelength) -Based on the luminescent properties of biological materials (includes blood, saliva, semen, urine) -Some substances will glow -Some substances will absorb light and darken when using ALS -Blood will darken to enhance its contrast by ~4 times. -This helps to photograph blood prints to allow for more details to be revealed

Alternate Light Sources Precautions

-Wavelength used could degrade sample -Safety precautions- must use proper personal protective equipment

RBC Transfusion

-What would happen if a type B blood person receives RBCs from a type A blood person? -The A antigen and the A antibodies can bind to each other just like B antigens can bind to the B antibodies. -The recipient type B blood has anti-A antibodies in the plasma. -These A antibodies present in the recipient blood will bind with the A antigens of the donated RBCs. -Agglutination occurs and then death of the recipient.

Plasma Transfusion

-What would happen if a type B blood person receives plasma from a type A blood person? -The A antigen and the A antibodies can bind to each other just like B antigens can bind to the B antibodies. -The donor type A blood has anti-B antibodies in the plasma. -These B antibodies present in the donors blood will bind with the B antigens of the recipients RBCs. -Agglutination occurs and then death of the recipient.

Knowing Types for Blood Transfusions

-When receiving blood, the blood groups must be compatible between the donor blood and the patient blood. -If they are not, the red blood cells from the donated blood will clump or agglutinate (clot) due to your body attacking the donate RBCs. -The agglutinated red cells can clog blood vessels and stop the circulation of the blood to various parts of the body. -This can have fatal consequences for the patient.

What Rh factor means

If mom is Rh- and baby is Rh+, while blood does not mix during pregnancy, during delivery a small amount could. If it does, mom can make Rh antibodies, but not a problem with first pregnancy. Next child...if next child is Rh+, the antibodies mom made can cross the placenta and damage the baby's RBCs and possibly cause anemia. Mom may be given an injection of Rh immune globulin which prevents the body from making Rh antibodies during the pregnancy. If mom is already making antibodies, injection will not work. Baby will be monitored and possible transfusion may be necessary.

Universal Recipient

Type AB

Universal Blood donor

Type O

Plasma

What is it? -The only liquid connective tissue in your body. -Straw colored Why is it important? -It allows the other 3 components of blood fluid to travel through the body! 55% of blood's volume is plasma. The other 45% is made up of blood cells. 90% water 10% other substances including: Glucose Amino acids Vitamins & minerals Urea Albumin (a protein) Fibrinogen (helps with clotting)

Antibodies

found in plasma. -These are against antigens, so these are what will cause problems with bad transfusions!

Antigens

found on the red blood cells. -These will tell what type of blood a person has. -Therefore, A antigen is present in Type A and AB, etc.

Granular

granules in the cytoplasm

Agranular

no granules (no dots) in the cytoplasm

Rh factors

protein substance found in the red blood cells of about 85% of the population

Red Blood Cells (RBC) - Erythrocytes

-5 million are found in one drop of blood. -Why are they so important? -Travel through your body delivering oxygen and removing waste. -Red blood cells are red because the contain a protein chemical and pigment, hemoglobin. -Hemoglobin plays an important function in transporting oxygen. -It contains iron which the oxygen molecules in your lungs attach to. -Oxygen is then released throughout your body as the blood circulates. -Does NOT contain a nucleus, so they cannot divide. -8.5µm in diameter -Made in the bone marrow -Recycled in the spleen -Live for 120 days -High affinity for oxygen and carbon monoxide -Refrigerated red cells last approximately 42 days

Use of Confirmatory Tests

-After preliminary tests, confirmatory tests will confirm that a stain is human blood. -After blood is confirmed, a lab may perform tests to determine the source, also referred to as "individualization." -Current test used is DNA analysis

Presumptive Tests

-Also referred to as preliminary tests, screening tests or field tests. -Establish the possibility a specific bodily fluid is present. -Do NOT conclusively prove the presence of a specific substance. -Can help to determine what test should be performed next. Pros: Narrows possibilities; can be used over large areas; can locate evidence not visible to the naked eye; can usually be performed at the scene; quick results Cons: risk of providing a false positives; can be overly sensitive

Blood is important!!

-Collects oxygen from the lungs -Collects nutrients from digestive tract -Collects waste products from tissue -It helps maintain balance inside the body (i.e. temperature) -Blood components help fight off infection -It can form clots to repair damaged blood vessels

Confirmatory Tests

-Conclusively identify the identity of a biological material. Pros: Conclusively identifies a substance; smaller risk of false positives Cons: Can be more expensive; take a longer amount of time; and require additional equipment

3 Questions to Answer Regarding Fluids at a Crime Scene

1. Is it a blood stain? 2. If yes, is it human blood? 3. If yes, can it be associated with a particular individual?

Examples of Presumptive Tests

1. Kastle-Meyer Test 2.Hemastix 3. Luminol 4. Alternative Light Sources

Examples of Confirmatory Tests

1. RSID (Rapid Stain Identification Series) Test for Human Blood 2. ABA Card Hematrace *DNA is not a confirmatory test for blood