Quiz #3 immune system/serology

Antigen

A foreign substance that stimulates the immune system

- viruses, parasites, endotoxins, foreign molecules (pollen)

Antibodies

Proteins, Immunoglobulins (Ig)

- consisting of 2 functional portions

• Variable portion: Binds only to specific Ag

• Constant portion: Ab binds to Ag to form a Ab-Ag complex

The Ag presence initiates _______ and ________ responses that __________, ________ and _________ foreign materials

1. Humoral and Cellular

2. neutralize, detoxify, and eliminate

Ag-Ab complex

Antibodies interacting with an antigen and the Ab lyses (killing/destroy) the foreign substance

Non-specific Defenses

INNATE immunity

- No memory

- Barriers to antigens (army)

- Non adaptive

- It elicits a the same response each and every time

- first line of defense

Specific/Acquired Defenses

- ADAPTIVE immunity

- Memory

- Humoral Immunity (HI): B cells

- Cell Mediated Immunity (CMI): T cells

- adaptive (special forces)

Examples of Non-specific immunity

- Intact skin and mucous membranes

- Secretions: tears, saliva, respiratory and intestinal secretions

- Mucociliary escalator of respiratory tract (nasal hairs)

- Chemicals: histamine, inflammatory meds

- Phagocytosis

What cells process and present an Ag to specific populations of lymphocytes before Ab can be produced

Phagocytes (neutrophils and macrophages)

What do B cells produce?

plasma cells which produce antibodies (memory cells)

Do B cells directly attack antigens?

Not, helper T cells stimulate B cells to produce Ab

Where are B cells produced and mature?

bone marrow

Where are T cells produced and mature?

produced in bone marrow, mature in thymus

B lymphocytes differentiate into what 2 cells?

1. Plasma cells: produce Ab/Ig/proteins

2. Memory B cells: respond faster to a second exposure to Ag by developing into plasma cells and making Ab

T helper cells produce what protein to activate B cells in order to divide and produce identical B cells that produce Ab to specific Ag

cytokines

Do B cells always make Ab right away?

No, some become memory cells

What is a titer

the concentration (level) of a certain antibody in serum

Cytokines

Chemical messengers that mediate the immune system

3 types of T cells

1. Cytotoxic T cells: "killer cells"

2. Helper T cells: help activate B cells with cytokines

3. Suppressor T cells: inhibiting killer T cells

What does a titer distinguish between?

Positive titer

1. An active infection

2. Prior exposure to certain Ag

3. Vaccine response

(Active) High titer means

Active infection: 3 fold increase over 3-4 weeks

Low titer

indicates previous exposure to specific Ag (maybe need for buster)

How long after 1st sample should 2nd sample be collected?

2-6 weeks

Seroconversion

the time period in which specific antibodies form and are detected in the blood

- usually occurs within a few weeks of infection/immunization

- 4 fold increase in Ab titer

Three types of antibodies

globular proteins, immunoglobulins, gamma globulins

IgG

immunoglobulin G

- Most abundant: Gorged (75%)

- Stays in circulation the longest

- Phagocytosis

- Neutralization

IgM

immunoglobulin M

- 1st to appear in response to exposed to Ag

- only 5% in circulation

- Largest Ab: Mega (Not able to enter tissue spaces)

- Phagocytosis

- Neutralization

IgE

immunoglobulin E

- Hypersensitivity reactions: think Eosinophils

- excess histamine release

- Found in allergic reactions, parasitized individuals

IgA

immunoglobulin A

- Prevents attachment to pathogens to mucosal surfaces: Anti attachment

- ex. intestinal and respiratory mucosa, tears, saliva

IgD

immunoglobulin D

- it exists hehe

5 signs of inflammation

redness, pain, heat, swelling, loss of function

Can more that 1 hypersensitivity reaction occur in reaction to a stimulus?

Yes

Hypersensitivity reactions

-The immune system reacts/responds to Ag that are normally ignored by the immune system

- It recognizes the body's own cells as foreign

Type 1: Hypersensitivity

Immediate Hypersensitivity Reactions

- excess IgE mediated

- Allergies and Anaphylaxis

- Inflammatory reactions

- Unusually, exaggerated, severe response

Anaphylactic reaction

A reaction that occurs after an Ag enters into circulation

- Local: Atopygenetic: predisposition to become allergic to pollens, molds, ect.

- Systemic: shock emergency

Type 2: Cytotoxic Hypersensitivity

Destruction of cells via Ab and complement or CMI

* Blood cell distraction secondary to:

- Bad transfusions

- Drug reactions: drug modifies cells and the body thinks they are foreign

- Rejection of grafts

- Autoimmune dz. (AIHA, ITP)

AIHA

Auto Immune Hemolytic Anemia

- RBC destruction due to phagocytosis

Pemphigus

Auto immune dz.

- affects skin and oral mucosa

- occurs due to reaction of Ab against the skin

ITP

Immune mediated Thrombocytopenia

- thrombocytopenia induced by Ab's produced against platelets

SLE

Systemic Lupus Erythematosus

- autoimmune disorder: multi-system dz.

Type 3: Immune Complex Hypersensitivity

Development of immune complexes (Ag/Ab)

-Local or systemic

- Ag/Ab complexes deposited in body tissues resulting in inflammation and tissue necrosis

- Chronic recurrent inflammatory dz.

- Ex. Rheumatoid arthritis, asthma, Inflammatory bowel dz.

Rheumatoid arthritis

chronic recurrent system inflammatory dz. involving joints and glomerular nephritis

Type 4: Delayed Hypersensitivity

CMI reaction where there are sensitized T cells from previous exposure

- reaction between sensitized T cells (macrophages) and Ag

- red, hard bumps and necrosis granulomas

Agrammaglobulinemia

lack of circulating Ab's, decrease in # of Ab's

SCID

Severe Combined Immunodeficiency

- Loss of CMI and HI (born without B and T cells)

- In Arabian foals (within 2 months of age, susceptable after maternal IgG from colostrum is gone

- spleen is affected

Cyclic Hematopoiesis

Gray Collie syndrome

- associated with abnormal skin pigmentation

- cyclic decteases in leukocyte count (episodes of immunosuppressed status)

- cycle is every 11 days

secondary immunosuppression

Can occur secondary to primary dz.

ex. viruses, bacterial and parasitic diseases, FeLV, FIV, cancers

Excessive immune reaction

Autoimmune Diseases:

- Rheumatoid arthritis (Type: III)

- AIHA (Type II)

- SEL (Type II or III)

- Drug related (Type II or III)

Does serology detect the quantity or quality of an Ab/Ag?

Quality (qualitative test)!!

Monoclonal Ab techniques

Type of specific Ab used for serology tests

- identical Ig molecules

- formed by single clone of plasma cells

- commercially produced for use in immunoassays

- usually must add a color substrate (blue) to be able to visualize the complexes

- Qualitative tests

Sensitivity test

ability of a test to detect true positives (out)

Specificity test

ability of a test to evaluate a given parameter to correctly ID patients without dz. True negative (in)

it is necessary to run + and - controls with every batch of serology tests?

Yes!!

ELISA test

Enzyme Linked Immunosorbent Assay

- High specificity to test for Ag's and Ab's

- Some test for Ag vs Ab

- Atigen: FeIV, HWT, Parvovirus kits

- Antibodies: FIV, E, canis, Lyme, Anaplasma

Can a FeLV vaccination affect the results of an ELISA test?

No, due to different Ags

The vaccine is P-70

ELISA tests for P-27 positive cats

What is a testing well coated with?

Ab directed against a specific Ag (monoclonal Ab coats)

What does the color change on an ELISA test indicate?

Only that the virus is present (Qualitative)

What test should be run to confirm FeLV?

IFA: tests for Ag in infected neutrophils and platelets

- presence of viral Ag indicated FeLV has infected the BM

- detects the viral Ag

Do Agar Gel Immunodiffusion tests see the quantity or the quality of the Ag/Ab?

Quantity (amount)

What does a Ag-Ab complex form on the gel agar plate?

line of percipitate

What does it mean when no band has formed between 2 circles on an agar plate?

No Ab exists in the patent's serum or Ab levels are too low to cause precipitation for that certain Ag.

Latex agglutination

Uses latex particles coated with an Ag and suspends in water

- serum (containing the Ab) is added to mixture

- If an Ag/Ab complex is present then you get agglutination (clumping) and the latex suspension changes from smooth to clumpy due to latex particles clumping together

IFA

Fluorescent Antibody Detection

Detect FA

The patients sample is added to a test slide that is pre-coated with a fluoresent dye Dg. The dye combines with a specific Ab in the patients serum

- examine under special microscope

Indirect FA

The primary Ab is unconjugated (no dye added) and a second Ab (containing fluorescent dye) is directed against the primary Ab used for detection

- Any fluorescence is a positive result

PCR

Polymerase Chain Reaction

- preformed in a reference lab

COOMBS test

Test for the presence of Ab to RBC (Ab against body's own tissue)

- Used to diagnose autoimmunehemolytic anemia (AIHA)

Direct COOMBS test

- detection of an antibody that has attached the RBC surface

- If the RBCs are coated with self-Ab, then a reaction takes place and you will see agglutination of the RBC

What immunity do titers measure?

Humoral Immunity (HI)

Interdermal skin test

Skin testing for Atopy

- place Ag interdermally and wait for IgE mediated Type 1 response

- Wheal and flare reaction