The Nature of Blood

12.1 Notes

Objectives List the A-B-O antigens and antibodies

found in the blood for each of the four blood types: A, B, AB, and O.

Understand and describe how whole blood is typed

Understand the concept of antigen-antibody interactions and how it is applied to species identification and drug identification

BloodA mix of cells, enzymes, proteins, and inorganic substances

Plasma – 55%Liquid, primarily water

Solid portion 45%Red Blood cells – erythrocytesWhite blood cells – leukocytesPlatelets

SerumThe pale yellowish liquid that makes up part of the blood clot

Pertinent to forensicsRed blood cells Blood serum

AntigensChemical structures found on the surface of the red blood cell

Impart blood-type characteristics

15 blood antigen systems have been identified More common are ABO and Rh (D)

AntigensType A blood contains A antigens Type B = B antigens Type AB = both A and B antigens Type O = neither A or B

Rh+ indicates the presence of D antigen

Rh- indicates the absence of D antigen

AntibodiesProteins that act against certain antigens Serum-containing antibody = antiserum

Considered bivalent Two reactive sites

Causes agglutination (clumping)

SerologyStudy of antigen-antibody reactions

US distribution of blood types:Type O – 43%Type A – 42%Type B – 12%Type AB – 3%

Donor Combinations

Blood Type Donates to Receives from

A A, AB A, OB B, AB B, O

AB AB allO all only O

AntibodiesProduced to bind to an invading antigen Different antibodies are produced to attack a particular antigen site

Polyclonal – multiple antibodies that attack different antigen sitesMay vary over time

Monoclonal antibodies - designed to attack only one site on an antigen

Process of producing monoclonals (p.335)

Inject mouse with a particular antigenMouse spleen cells produce antibodies

Spleen cells removed and fused to cancer cellsCombined cells are called hybridoma cells

Hybridoma cells allowed to multiply and are screened for antibody activity

Process continuedHybridoma that bear antibody activity of interest are selected, removed and culturedProduce identical monoclonal antibodies in endless supply

Used to offer immunoassay test for certain drugs and semen material

Current and most well known use of monoclonal antibodies is Rituxin (cancer treatment)

12.1 Questions1. Who discovered that blood is distinguishable by its group or type?

2. What blood factors are the most important for properly matching a donor and recipient for a transfusion?

3. What technique supplanted blood typing for associating bloodstain evidence with a particular individual?

4. What is plasma? What percentage of blood content does plasma account for?

5. Which of the following types of cells are not contained in plasma?A. PhagocytesB. LeukocytesC. ErthyrocytesD. Platelets

6. What are antigens and antibodies? What part of the blood contains antibodies?

7. Describe how antibodies and antigens determine one’s A-B-O blood type.

8. What is the fourth important antigen other than A, B, and O?