Immune System

Antigen

an organism or toxin that creates a hostile or unfriendly environment for life

bacteria, viruses, protozoans, fungi, parasites, abnormal cells

What are some examples of antigens?

Innate Immune System

a collection of non-specific bodily defenses

-skin

-physical and biochemical components

-species resistance

-inflammatory response

- NK cells, interferons, complement systems

Adaptive Immune System

acquired immunity - third line of defense

-responds specifically to antigen

-neutralizes, detoxifies, and destroys antigens

-two systems: humoral, cell-mediated

-involves lymphocytes and macrophages

Lymphocytes

mostly active in adaptive immune system, some active in innate immune system, some

Macrophages

active in both adaptive and innate immunity

- innate: bind to, phagocytize, and kill pathogens

- adaptive: process antigens and present them to antigen commited lymphocytes

felines cannot get canine distemper

What is an example of species resistance?

Inflammatory response

second line of defense

- 4 steps

-involves mediators, neutrophils, monocytes, clotting factors

Step 1 of Inflammatory Response

mediators released - blood vessels dilate, neutrophils enter

Step 2 of Inflammatory Response

neutrophil phagocytize- kill pathogen with chemicals stored in cytoplasm

Step 3 of Inflammatory Response

clotting factors - prevent spread of pathogen

Step 4 of Inflammatory Response

monocytes - follow neutrophils - eat and kill pathogens

-become macrophages when they enter tissue

Other Name for Inflammatory Response

mononuclear phagocytic system

Other regions that can release macrophages

connective tissue, liver, lung, brain, spleen, bone marrow, lymph nodes

Clinical Signs of Inflammatory Response

pain, heat, swelling, loss of function, redness

increased temps kills pathogens and mediates clotting factors

Why is heat important in the inflammatory response?

Natural Killer Cells, NK cells

small subset of lymphocytes found in blood and peripheral lymphoid organs

-adaptive and innate response

Functions of NK cells

-recognize and destroy infected host cells

-release interferons - activate phagocytes

-release cytokines that create other cellular reactions

-mediate immune responses

Interferon

a cytokine that inhibits viral replication

Complement System

proteins in the blood active in the adaptive and innate immune system that work to destroy pathogens

-cascade C1-C9

-three pathways- all end with same steps

Final Steps of all Complement System Pathways

-complement binds to invading cell wall and causes small holes in the cell membrane leading to cell lysis

-opsonization

Opsonization

phagocytes adhere to enhance phagocytosis of antigen

alternative, classical, lectin

What are the three pathways of the complement system?

mannose binding lectin

What is another name for the lectin pathway?

Lymphoid Stems Cell Development

-start in yolk sack

-migrate to fetal liver

-travel to bone marrow close to partruition

bone marrow

B lymphocytes originate in the _______.

thymus

T lymphocytes originate in the _____.

Humoral Immune System

response helped by B cells that create circulating antibodies against antigens

Stages of Maturity for Lymphocytes

-lymphoblast

-prolymphocyte

-lymphocyte

secondary lymphoid organs, spleen, lymphnodes

When B cells mature, they migrate from bone marrow to these organs, where they come in contact with antigens?

they produce cytokines to activate B cells

What is the function of helper T cells in the humoral immune system?

billions, specific receptor molecules

The body's B cells can recognize ________ of antigens, since they develop, ______ ______ _____ for specific antigens

same, plasma, effector

Activated B cells create duplicates of themselves with the ____ antibodies, known as _____ or ____ cells that are released in the bloodstream.

Plasma cells

B cells that perform specific functions to destroy antigens

Memory Cells

B cells that remember antigens in the case of a second exposure

-allows for faster response

Immunoglobulin structure

2 pairs of polypeptide chains

-2 regions: Fc and Fab

Fc region

constant region - fxn of antibody, classes

Fab region

2 variable regions that bind to antigen

Classes of Immunoglobulins

-IgM

-IgG

-IgE

-IgA

-IgD

IgM

~5% of antibodies, activation of complement

-relatively large, cannot enter tissues

IgG

most abundant Ig ~75%

-remains in circulation the longest

-small, can enter tissue spaces

-produced during secondary immune response

IgG functions

-neutralize microbes and toxins

-opsonization

-activate complement

-passive transfer thru placenta and colostrum

IgE

present in small amounts, responsible for defense against allergens (allergies), anaphylaxis, and helminth parasites

IgA

~20% of circulating antibodies

-mucosal immunity- protects respiratory, intestinal, and urogenital tracts

IgD

found in very low abundance or not at all

-B lymphocyte surface antigen in some species

Process of Antibody destroying Antigen

-Fab region binds to antigen

-Fc region binds to macrophage or neutrophils

-Antigen phagocytized

1

The are _____ type(s) of antigen for each antibody.

specific antigens, antigen-committed

As T cells mature, they develop receptors for ______ _____ and become _________________ T lymphocytes.

Memory T cells

T cells that recognize antigen they have previously been exposed to elicit a more rapid response

Helper T cells

recognize antigens that have been phagocytized by an antigen presenting cell (APC) like macrophages

Immunologic Tolerance

body's ability to recognize itself vs antigens

-can fail = autoimmune disease

Passive Immunity

short-lived, immediate protection

-maternal antibodies (placenta, colostrum)

-injections (antibodies from donor animal)

Vaccinations and Immunizations

active immunity

-elicit immune response

-do not cause disease

Attenuated Vaccines

weakened antigen

-longer lasting, more potent response

Inactivated or Killed

safer vaccine, less risk of disease

-require more adjuvants

DNA vaccines

developed using molecular genetic

-quicker to make, safer

Adjuvants

may be added to improve immune response, increase time antigen remains in body

vaccine-related sarcoma

What disease can adjuvants cause in cats?

Administration of Vaccine

-subcutaneously

-intramuscularly

-intranasally

-through food or water

rapid antigen test

What is one way to test a vaccine's effectiveness?