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Acquired Immunity
In acquired (adaptive immunity) a specific response is enlisted. The cells involved have the ability to recognize the specific agent and mount a powerful response
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Innate Immunity
- Innate (natural immunity) is nonspecific and provides the first line of defense against invading pathogens
- skin
- mucous membranes
- pH in skin
- acid in stomach
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Primary Response
- Elicited on first exposure to a foreign antigen
- Lag phase of 5-7 days before antibody can be detected in the host
- Following the lag period, antibody levels rise, plateau, and then decline
- IgM antibodies are produced first then IgG are producted
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Secondary Response
Also called anamnestic response because there are memory cells
Happens within 1-2 days of Ag exposure with significant amount of antibody production
Principal antibody is IgG, unlike primary response in which IgM is the principal antibody
1,000 times more antibody and slow decline
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What Influences Ag-Ab Binding
- Goodness of fit
- Strength and rate of reaction
- Size, Shape, and Charge
- Affinity: The strength of binding between a single antibody and epitope of an antigen
- Avidity: The overall strength of reactions between several epitopes and antibodies
Epitope made of sugar and lipids
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Prozone
The concentration of antibody exceeds the antigen concentration
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Zone Of Equivalence
- Maximum agglutination occurs when the concentrations of antigen and antibody are in the zone of equivalence
- Same amout of antibody and antigen
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Postzone
The concentration of antigen exceeds antibody concentration
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Why is the concentration of the red cell suspension important and what is a good percent?
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Red cell agglutination grading
- 4+ red cell button is a solid agglutinate, with a clear supernatant background
- 3+ red cell button breaks into several large agglutinates, with a clear background
- 2+ red cell button breaks into many medium sized agglutinated, clear background, no free RBC
- 1+ red cell button breaks into many small clumps barely visible macroscopically, background is turbid with many unaggutinated red cells
- 0 no agglutinated red cells visible, red cells are observed flowing off the red cell button during the process of grading
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IgM
First class of antibodies produced by B cells or plasma cells when an Ag is encountered
Pantamer shape, 5 units held together by J chains
Can agglutination of red cells in saline at room temp
Constitutes 5%-10% of total serum antibody
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IgG
Consists of a single four chain unit
Does not agglutinate red cells in saline
Reacts optimally at 37 degrees C
Can cross the placenta and cause HDFC
Makes up 80% of Ab concentration in the serum
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Antibody Molecule
Heavy chain constant region has the function of the class. The variable region is unique and gives it specificity
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Antiglobulin Test
Detect IgG antibodies on the red cell. Differ between direct and indirect
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Direct Antiglobulin Testing (DAT)
- Identify red cells that have been sensitized to IgG or complement in vivo
- cells must be washed to remove excess antibody so it doesn't neutralize the AHG (Coombs) reagent
- No incubation necessary because the reaction has already occured in vivo
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Indirect Antiglobulin Test (IAT)
- Designed to detect in vitro sensitization of red cells
- Two step method by which serum is incubated at body temp (37 degrees) with a red cell source allowing for binding of antibody
- Excess antibody is thoroughly washed and the AHG reagent is added
- Aggulitination indicates a positive result
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Monoclonal
- A created clone that contains antibodies of a defined specificity
- Monoclonal antibody is produced in vitro
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Polyclonal
- Usually derived from the injection of animals or humans with purified antigens
- Polyclonal product contains several clones of B-cell antibody
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Reagents that will enhance a reaction
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Rh control
- If a high protein anit-D is used then a Rh control required
- This is to verify positive reaction
- Make sure it is not caused by some additive or reagent
- This is the reason to use monoclonal
- If there is a positive reaction with anti-D and the D control is also positive then the test is invalid
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Antiglobulin reagents
Polyspecific AHG reagents are used primarily in direct antiglobulin testing (DAT) and contain antibodies to both IgG and C3d
Monospecific reagents are preparedd by separating the polyspecific products into either IgG, AHG, or C3d AHG
AHG is commercially available as polyclonal or monoclonal serum based
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Screening cells
- Used in antibody screen tests
- Obtained from type O individuals
- Available as two or three vial sets
- FDA requires that the cells detect the most clinically significant antibodies
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Phenotype
Serologic testing determines the presnece or absence of antigens on red cells
The phenotype is the physical expression of inherited genes
More specifically the antigens found on red cells
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Genotype
The actual genes inherited from each parent
Can be inferred only from the phenotype
Family studies are required to determine the actual genotype
Predicting the genotype from a phenotype is important in paternity studies or when determining a fetus' probable phenotype
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Pedigree charts
- Examination of family history
- Allows the important elements of patterns to become more visibly apparent
- Can illustrate the difference between genotype and phenotype
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Punnett squares
Illistrate the probabilities of phenotypes from known or inferred genotypes
Figuring out blood types
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Heterozygous
Refers to different blood system alleles from each parent (AO)
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Homozygous
Both parents contributed the same gene, giving a double dose of antigen (AA, BB)
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Crossing over
Exchange of genetic material during meiosis between chromosomes
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FDA
Food and Drug Administration
- Ensures the safety and efficiency of blood, blood components, and testing reagents
- Requires licensing of manufactureres and products
- Regulates labeling and facilities
- Penalties for violation
- FDA inspections
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OSHA
Occupational Safety and Health Administration
- OSHA passed by congress in 1970
- Defines biosafety levels based on potential exposure to infectious material
- Ensures a safe, healthful work environment
- All accidents must be reported
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CDC
Centers for Disease Control and Prevention
- Introduced in 1987
- Introduced to reduce the risk of occupational exposure to blood borne disease
- Treat all substances are potentially infectious
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EPA
Environmental Protection Agency
Became involved in the assessment of medical waste in 1988
Required to determine types, numbers, and sizes of generators of medical waste in the US
Examines present or potential threat of medical waste to human health and the environment
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DOT
Department of Transportation
DOT regulates diagnostic materials and etiologic agents shipped between states and foreign countries
Governs all ground transportation
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TJC
The Joint Commission
Accrediting agency by which orginizations elect to be inspected and accredited
Blood bank included in inspection
Safety requirements incorporate general safety, hazardous chemicals, and equipment
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AABB
Voluntary
Standards for blood bank and transfusion services, provides the basis for inspection and accreditation
High standards
Safety is a large component of the inspection process
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CAP
Voluntary
- Provides peer reviewed accreditation for labs
- Recognizes accreditation by CAP as equivalent to it's standards
- Includes inspection and observation of safety compliance
- Uses comprehensive checklist
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