INFECTIOUS DSS INTRO COMPILED

Immunity

- The body's specific protective response to a foreign agent or organism

- the most common role of the immune system

Immune System

Functions as the body's defense mechanism against invasion

Immune Memory

property fo the immune system that provides the protection against harmful microbial agents despite the timing of the re-exposure to the agent.

Tolerance

mechanisms programmed to eliminate foreign substances but maintains to accept self-antigens.

CNS Integrity

top most factor affecting the immune system

Steroids

- medications that are known immunosuppressant

- lowers the function of the immune system

Cortisol

- hormone produced in times of stress

- known immunosuppressant

Bone Marrow

where WBCs are produced

White blood cells

- play an important role in the function of the immune system

- "soldiers" of the immune system

- known to attack and kill foreign invaders

types of lymphocytes

- B lymphocytes (B cells)

- T lymphocytes (T cells)

B lymphocytes/B cells

Mature in the bone marrow & then enter the circulation once they mature

T lymphocytes/T cells

Move from the bone marrow to the thymus, where they mature and develop into several kinds of cells with different functions.

Spleen

- known to act as a filter

- It has 2 pulps present: The Red pulp and the White Pulp

Red pulp

- where old and injured RBCs are destroyed

- Ultimate function of the spleen, in fact it is called the "graveyard" of the RBCs

White pulp

- contains concentrations of lymphocytes

- These lymphocytes are able to mature and are able to attack or kill microorganisms that invade the body

Lymph nodes

- Connected by lymph channels and capillaries, are distributed throughout the body

- Remove foreign materials from the lymph system before it enters the bloodstream

- Centers for immune cell proliferation

Types of immunity

- Natural (nonspecific immunity)

- Acquired (specific immunity)

Natural Immunity/Nonspecific immunity

- Present at birth

- Provides a broad spectrum of defense against & resistance to infection

- Considered as the first line of the host defense

- Protects without "remembering" prior contact with an infectious agents

Natural Immunity/Nonspecific immunity

Co-coordinates the initial response to pathogens through the production of cytokines and other effector molecules, which either activate cells for control of the pathogen (by elimination) or promote the development of the acquired immune response

Types of Natural Immune Mechanisms

- Immediate

- Delayed

Immediate

Generally occurring within 4 hours

Delayed

Occurring between 4 to 96 hours

Functions of Natural Immunity

- White blood cell action

- Inflammatory response

- Physical & chemical barriers

- Immune regulation

Granulocytes

- include neutrophils, eosinophils & basophils

- fight invasion by foreign bodies or toxins by releasing cell mediators, such as histamine, bradykinins & prostaglandins & by engulfing foreign bodies or toxins

Neutrophils

- polymorphonuclear leukocytes or PMNSs

- First cells to arrive at the site where inflammation occurs

Eosinophils and Basophils

Increase in number during allergic reactions & stress

responses

Monocytes

Function as phagocytic cells, engulfing, ingesting, and destroying greater numbers and quantities of foreign bodies or toxins than granulocytes do

Lymphocytes

- Consisting of B cells and T cells

- Play major roles in humoral (B cells) and cell-mediated (T cells) immune response

Inflammatory Response

- Major function of the natural immune system

- Elicited in response to tissue injury or invading organisms

- Chemical mediators assist this response by minimizing blood loss, walling off the invading organism, activating phagocytes, and promoting formation of fibrous scar tissue and regeneration of injured tissues.

Physical Barriers

- include intact skin, mucus membranes and cilia

- prevents pathogen from gaining access to the body

Chemical Barriers

Acts in a nonspecific way to destroy invading bacteria & fungi

Interferon

- are basically components of your immune system which are known to be virucidal

- counters viruses

Immune Regulation

- Involves balance and counterbalance

- natural immunity regulates the immune cells TO DO

their functions when there is a foreign invader or tissue injury and it ALSO regulates the immune cells TO STOP when there is no longer the need to do its job

Immune Tolerance

- Mechanism wherein the immune system is programmed to eliminate foreign substances but maintains the ability to accept self-antigen

- hastens the function of the immune cells

Immunocompromised/Immunodeficient

the immune system fails to develop and clear the antigen sufficiently

acquired immunity/specific immunity

- develops after birth

- also known as adaptive immunity

- Develops as a result of prior exposure to an antigen through immunization or by contracting a disease

acquired immunity/specific immunity

The body produces an immune response that is sufficient to defend against the diseases on re-exposure

Mechanisms of Acquired Immunity

- Cell-mediated response

- Effector mechanism

cell-mediated response

involves t cell activation

effector mechanisms

involves b cell maturation and production of antibodies

active acquired immunity

- refers to immunologic defenses developed by the person's own body

- Typically lasts for many years or even a lifetime

- through vaccines

active acquired immunity

Virus is introduced in the system so that necessary cells will evolve and produce a blueprint on how to kill such organisms

passive acquired immunity

Temporary immunity transmitted from a source outside of the body that has developed immunity through previous disease or immunization

passive acquired immunity

Immune globulin or immunity resulting from the transfer of antibodies from the mother to an infant in utero or through breastfeeding

passive acquired immunity

Preformed antibodies given to the person that already has the specific disease

Phagocytic Immune Response

- First Line of defense (Natural)

- Primarily involves the WBC (granulocytes & macrophages) which has the ability to ingest foreign particles and destroy the invading agent

Humoral Immune Response/Antibody Immune Response

- 2nd Line of defense

- Sometimes called the antibody response because it is

characterized by the production of antibodies by B lymphocytes in response to a specific antigen.

Immunoglobulins

- antibodies; large proteins

- Produced by the mature B cells which consists of two subunits, each containing a light and heavy peptide chain held together by a chemical link composed of disulphide

bonds

Immunoglobulins

- promote the release of vasoactive substances (i.e. Histamine)

- Do not function in isolation; rather, they mobilize other components of the immune system to defend against the invader

Agglutination

- binding or clumping together of 2 or more antigens

- One antibody can act as a cross-link between 2 antigens, causing them to bind or clump together, which helps clear the body of the invading organisms by facilitating phagocytosis.

Opsonization

- Where the antigen-antibody molecule is coated with a sticky substance that also facilitates phagocytosis

- also promote the release of vasoactive substances

Types of Immunoglobulins

- IgG

- IgA

- IgM

- IgD

- IgE

IgG

- Assumes a major role in bloodborne and tissue infections

- Activates the complement system

- enhances phagocytosis

IgG

- crosses the placenta

- 75% of the total immunoglobulins and appears in the scrum and tissues

- majority of immunoglobulins

IgA

- Protects against respiratory, gastrointestinal, & genitourinary infections

- Prevents absorption of antigens from food

IgA

- Passes to neonate in breast milk for protection.

- 15% of the total immunoglobulins

- Appears in body fluids

IgM

- Appears the first immunoglobulin produced in response to bacterial & viral infections

- Activates the complement system

IgM

- 10% of the total immunoglobulin

- Appears mostly in intravascular serum

IgD

- Possibly influences B lymphocyte differentiation, but role is unclear.

- 0.2 % of total immunoglobulin

- Appears in small amount in serum

IgE

- Takes part in allergic & some hypersensitivity reactions

- Combats parasitic infections

- Appears in serum

- when activated, it can kill you

Antigen-Antibody Binding/Immune Complex

when an antibody meets an antigen

Antigenic Determinant/Immunogenic Epitopes

The portion of the antigen involved in binding with the antibody

cross-reactivity

an antibody that was produced in response to a different antigen

Cellular Immune Response

- 3rd line of defense

- Involves the T lymphocytes, where they attack invaders directly

Cellular Immune Response

initiated, with or without the assistance of macrophages, by the binding of an antigen to an antigen receptor located on the surface of a T cell

T cells

they carry the antigenic message (blueprint) to the lymph nodes

Lymph nodes

- where the production of other T cells is stimulated

- some T cells remain here and retain a memory of the antigen

Types of Lymphocytes

- Effector T cells

- Suppressor T cells

- Memory T cells

- Null lymphocytes

- Natural Killer Cells (NK cells)

Effector T cells

Types:

- Helper T cells

- Cytotoxic T cells

Helper T cells/CD4+ cells

When activated, secrete cytokines, which attract & activate B cells, cytotoxic T cells, NK cells (or natural killer cells), macrophages, & other cells of the immune system.

Cytotoxic T cells/CD8+ cells

Attack the antigen directly by altering the cell membrane & causing cell lysis & by releasing cytolytic enzymes & cytokines

Suppressor T cells

Have the ability to decrease B-cell production, thereby keeping the immune response at a level that is compatible with health

Memory T cells

Responsible for recognizing antigens from previous

exposure and mounting an immune response

null lymphocytes

- Types of lymphocytes that destroy antigens already

coated with an antibody.

- Have special receptor sites on their surface that allow them to connect with the end of antibodies

antibody-dependent, cell-mediated cytotoxicity

The function of the null lymphocytes

Natural Killer Cells/NK Cells

- Recognize infected and stressed cells.

- respond by killing these cells and by secreting macrophage-activating cytokine

Complement System

Plasma proteins made in the liver and activated when an antibody connects with its antigen

Complement System

3 major roles:

- Defending the body against bacterial infection

- Bridging natural and acquired immunity

- Disposing of immune complexes and the by-products

associated with inflammation

Complement Pathways

- Classic Pathway

- Lectin Pathway

- Alternative Pathway

Classic Pathway

triggered to be activated once the antibodies bind to the microbes and other antigens and is part of the humoral type of adaptive immunity

Lectin Pathway

- binds to terminal mannose residue on the surface glycoproteins of microbes.

- Activated when a plasma protein (mannose-binding lectin) binds to terminal mannose residue on the surface glycoproteins of microbes

Alternative Pathway

- Triggered when complement proteins are activated or already finding themselves on microbial surfaces

- Part of the natural immunity

Function of the complement system

protects in 3 ways against infection

- bind to pathogens, opsonizing them for engulfment

- Act as chemoattractant to recruit more phagocytes

- Terminal complement components damage certain bacteria by creating pores in the bacterial membrane

Immunomodulators

- Also known as biologic response modifier

- Affects the host via direct or indirect effects on one or

more components of the immunoregulatory network.

Interferons

- non-specific virucidal protein that is naturally produced by the body & is capable of activating other components of the immune system.

- Have an antiviral & antitumor properties

Interferons

- Produced by the B lymphocytes, T lymphocytes & macrophages in response to antigens

- Thought to modify the immune response by suppressing antibody production & cellular immunity

Interferons

- Facilitate the cytolytic role of macrophages & NK cells

- Are now used to treat immune-related disorders (multiple sclerosis) & chronic inflammatory conditions (chronic hepatitis)

Colony-stimulating Factors

Group of naturally occurring glycoprotein cytokines that regulate production, differentiation, survival, & activation of hematopoietic cells

Colony-stimulating Factors

Examples:

- Erythropoietin

- Thrombopoietin

- Interleukin 5 (Il-5)

- Stem cell factor & Il-5

- Monoclonal Antibodies (MoAbs)

Monoclonal Antibodies (MoAbs)

- Destroy pathogenic organism and spare normal cells.

- Specificity depends on identifying key antigen proteins present on the surface of tumors, but not on normal tissues.

- Blocks important signal transduction pathway for communication between the malignant cells and the extracellular environment.

Monoclonal Antibodies (MoAbs)

Results:

- Inability to initiate apoptosis especially with the normal cells.

- Inability to reproduce by the malignant cells.

- Inability to invade surrounding tissues

Stages in Immune Response

1. Recognition Stage

2. Proliferation Stage

3. Response Stage

4. Effector Stage

Recognition Stage

- Initiating event: Recognition of antigens as foreign or non-self.

- Involves the use of lymph nodes and lymphocytes for surveillance.

Proliferation Stage

- Once a foreign invader is recognized, the circulating lymphocytes containing the antigenic message that identifies the foreign body return to the lymph nodes

- Once in the node, these sensitized lymphocytes stimulate some of the resident T & B lymphocytes to enlarge, divide, and proliferate.

Response Stage

- The differentiated lymphocytes function in either a humoral or a cellular capacity.

- Begins with the production of antibodies by the B lymphocytes in response to a specific antigen.

Response Stage

The cellular response stimulates the resident lymphocytes to become cells that attack the microbes directly rather than through the action of antibodies (cytotoxic [killer] T cells).

Effector Stage

Stage where either the antibody of the humoral response or the cytotoxic (killer) T cells of the cellular response reaches and connects with the antigen on the surface of the foreign invader

Effector Stage

This initiates activities involving interplay of antibodies (humoral immunity), complement system, and action by the cytotoxic (killer) T cells (cellular immunity)

Cellular response

predominant immune response in viral infection and transplant rejection

humoral response

predominant immune response in bacterial infection