HUMAN IMMUNE SYSTEM

IMMUNE SYSTEM Few systems in nature are as complicated as

the human immune system. It exists apart from, and works in concert with, every other system in the body. When it works, people stay healthy. When it malfunctions, terrible things happen.

The main component of the immune system is the lymphatic system. Small organs called lymph nodes help carry lymph fluid throughout the body. These nodes are located most prominently in the throat, armpit and groin. Lymph fluid contains lymphocytes and other white blood cells and circulates throughout the body.

IMMUNE SYSTEM (CON’T)

The white blood cells are the main fighting soldiers in the body's immune system. They destroy foreign or diseased cells in an effort to clear them from the body. This is why a raised white blood cell count is often an indication of infection. The worse the infection, the more white blood cells the body sends out to fight it.

NON-SPECIFIC IMMUNE RESPONSE

first line of defense, is a subsystem of the overall immune system that comprises the cells and mechanisms that defend the host from infection by other organisms in a non-specific manner.

InflammationAnatomical barriers (epithelial surfaces)White Blood CellsMast CellsPhagocytes

SPECIFIC IMMUNE RESPONSE

a subsystem of the overall immune system that is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogen growth.Acquired immunity is triggered in

vertebrates when a pathogen evades the innate immune system and (1) generates a threshold level of antigen and (2) generates "stranger" or "danger" signals activating dendritic cells.

Lymphocytes Antigen presentation Exogenous antigens Endogenous antigens

ACTIVE IMMUNITY active immunity indicates that you directly

form antibodies upon contact with an antigen, which is another term for foreign organisms that cause reactions to the body’s defense mechanisms. Only with the presence of antigens will your body form such antibodies.

Active immunity indicates the formation of antibodies through direct exposure to an antigen.

Active immunity is divided into 2 subtypes, active-natural and active-artificial. i.e. Immunizations (MMR, Polio, Chicken Pox, etc.)

PASSIVE IMMUNITY

passive immunity, individuals do not have the antibodies, but rather, are passed down to them naturally or through human intervention. The antibodies given are already working and can protect the recipient from illness.

Passive immunity means that antibodies are passed down to a recipient, even without exposure to an antigen.

Passive immunity has 2 subtypes, passive-natural and passive-artificial.

VACCINE• inoculation: a preparation containing weakened or

dead microbes of the kind that cause a disease, administered to stimulate the immune system to produce antibodies against that disease.

• Vaccines are harmless agents, perceived as enemies. They are molecules, usually but not necessarily proteins, that elicit an immune response, thereby providing protective immunity against a potential pathogen. While the pathogen can be a bacterium or even a eukaryotic protozoan, most successful vaccines have been raised against viruses and here we shall deal with anti-viral vaccines.

VACCINE TYPES OF VACCINES: Killed vaccines: These are preparations of the normal

(wild type) infectious, pathogenic virus that has been rendered non-pathogenic, usually by chemical treatment such as with formalin that cross-links viral proteins.

Attenuated vaccines: These are live virus particles that grow in the vaccine recipient but do not cause disease because the vaccine virus has been altered (mutated) to a non-pathogenic form; for example, its tropism has been altered so that it no longer grows at a site that can cause disease.

Sub-unit vaccines: These are purified components of the virus, such as a surface antigen.

DNA vaccines: These are usually harmless viruses into which a gene for a (supposedly) protective antigen has been spliced. The protective antigen is then made in the vaccine recipient to elicit an immune response

SUCCESSFUL VACCINES SMALL POX RABIES POLIO MUMPS MEASELS RUBELLA INFLUENZA HEPATITIS A & B

DISADVANTAGES OF ATTENUATED (WEAKENED, DILUTED, THINNED, REDUCED,

WEAKENED, DIMINISHED) VACCINE

Mutation. This may lead to reversion to virulence (this is a major disadvantage)

Spread to contacts of the vaccinee who have not consented to be vaccinated (This could also be an advantage in communities where vaccination is not 100%)

Spread of the vaccine virus that is not standardized and may be mutated

Sometimes there is poor "take" in tropics Live viruses are a problem in immunodeficiency

disease patients

ADVANTAGES OF INACTIVATED VACCINE

They give sufficient humoral immunity if boosters given

There is no mutation or reversion (This is a big advantage)

They can be used with immuno-deficient patients

Sometimes they perform better in tropical areas

DISADVANTAGES OF INACTIVATED VACCINES

Some vaccinees do not raise immunity Boosters tend to be needed There us little mucosal / local immunity

(IgA). This is important (figure 8) Higher cost In the case of polio, there is a shortage

of monkeys In the case of smallpox, there have been

failures in inactivation leading to immunization with virulent virus.

ANTIBIOTIC RESISTANCE

Drug resistance means any drug classified as an antimicrobial that has been compromised or has reduced or no activity when used to treat certain microbes (viruses, bacteria, fungi and parasites).

Antibiotics are medicines designed to kill or stop or slow growth of bacteria (and some fungi) while an antibacterial substance is designed to kill or slow bacterial growth.

ANTIBIOTIC RESISTANCE

Causes Microbes, such as bacteria, viruses,

fungi, and parasites, are living organisms that evolve over time. Their primary function is to reproduce, thrive, and spread quickly and efficiently. Therefore, microbes adapt to their environments and change in ways that ensure their survival. If something stops their ability to grow, such as an antimicrobial, genetic changes can occur that enable the microbe to survive. There are several ways this happens.

IMMUNE SYSTEM ASSIGNMENT:

Describe the basic functions of the human immune system.

Including:

Specific immune responseNon-specific immune responseActive ImmunityPassive ImmunityAntibiotic ResistanceVaccines