body defenses, immunity, and vaccines

Body Defenses, Immunity, and Vaccines

B&S

CH 17

Immune System

• This is the system that fights harmful organisms and invaders

• The immune system is made up partly of the lymph system and of specific fighting cells

Immune System

• Bugs, strep, viruses all enter the body some how. Certain bugs enter the body a certain way for example:

• The cold virus (which ever strand it is) likes to leave one person through sneezing or a kleenex and enter another person through their nose or by being inhaled and enter through mucous membranes

Portal of Entry

• We discussed this earlier

• Resp. tract is most common entrance route for pathogens

• Digestive system and tubes into the urinary tract, or a break in the skin are other ways bugs enter the body

Virulence

• How aggressive or powerful is the bug• Does it produce toxins that are poisons

that damage the body

• Different organisms vary in virulence

• Organisms can change and may gain more virulence as they pass from one infected host to another

Dose

• This refers to the # of pathogens

• If the troops are big in #, it will take more fighting to get rid of them

Predisposition of host

• Is the person or host in good condition emotionally, physically, these include living habits and age

Line of defense

• These are the features that protect the body against disease beginning with the simple outer barriers and proceeding through progressively more complicated responses until the ultimate defense mechanism of immunity, is reached

Line of Defense

• SKIN – serves as a mechanical barrier against invaders through the skin

• Burn pts are at serious risk for infections if they don’t have that protective coat

• Mucous Membranes – keep germs out by causing the germs to stick to the mucous. Cilia in the membrane also help sweep debris and keep it from getting in

• Body Secretions – like tears, perspiration, and saliva, wash away microorganisms or kill it off because these body fluids contain acid, enzymes or other chemicals that are good at destroying invaders

Phagocytosis

• This is the 2nd line of defense against invaders

• WBC’s invade the bad spot and destroy waste and foreign materials

The main Phagocytic WBC

• Neutrophils – (granular leukocytes)

• Macrophages –

• Both of these blood cells travel in the blood to the sites of infection

• Some macrophages remain fixed in a certain part of the body like in the skin, liver, lungs, lymphoid tissue, bone marrow to do a specific job

Natural Killer Cells

• This is a different type of lymphocyte

• Natural Killer cells can recognize body cells with abnormal membranes such as in tumor cells or in cells infected with virus

• Natural Killer cells destroy the bad cells on contact

Inflammation

• Is the body’s effort to get rid of anything that irritates it

• Friction, fire, chemicals, x-rays, cuts or blows can all be classified as irritants

• If the irritant is d/t pathogenic invasion, the resulting inflammation is called “infection”

Inflammatory Reaction

• With the entrance of a pathogen, a whole series of defensive processes begins:

• 4 classic symptoms

• 1. heat

• 2. red

• 3. swelling

• 4. pain

Histamine

• When tissues are injured, histamines are released from the damaged tissue causing small blood vessels to widen or dilate

• More blood then flows to that area resulting in the 4 classic symptoms:

• 1. runny nose, sneezing• 2. hypotension• 3. swelling of tissue• 4. hives

• With the increase of blood flow comes a vast # of leukocytes and now something new happens…

• Now, the walls of the tiny blood vessels become coarsened in texture just like a piece of cloth when it is stretched

• Blood flow slows down, leukocytes move through these altered walls and into tissue where they can get at the irritant directly

• The whole clotting cascade starts, fluids leak out of the vessels from the blood plasma and begins to clot

Inflammatory exudate

• Is the mixture of fluid and leukocytes, this fluid causes pressure on nerve endings

• This extra fluid and the increased amt of blood in the vessels is why we feel pain from inflammation

Pus

• As phagocytes do their work, they die off rapidly

• The area around the injury eventually becomes filled with dead leukocytes

• The mixture of exudate, living and dead blood cells, pathogens and destroyed tissue is now called “PUS”

Lymphatic System

• Now the lymphatic system begins to drain fluid from the inflamed area and carry it toward the lymph nodes for filtration

• The regional lymph nodes near the injury become enlarged and tender which is a sign that they are performing their protective function by producing phagocytic cells to “clean” the lymph flowing through them

Fever

• When your body temperature rises above normal, this can be a sign that body defenses are at work

• When phagocytes are exposed to infecting organisms, they release substances that act to raise body temperature

Fevers

• Fever boosts the immune system in many ways:

• Fever:

• Stimulates phagocytes

• Increases metabolism

• Decreases the ability of certain organisms to multiply

Fevers

• Are normal reaction of the body during infection or invasion of some organism

• Advertisers make people believe that fevers are “BAD” and that they should always be eliminated

• We need fevers to help us to get better and to also warn us of some pathogen that has entered the body

How to treat fevers

• Acetominophen (Tylenol)

• Children: 10-15mk/kg Q 4hr (Don’t be afraid to give the max amount)

• Adults: 325-650mg Q 4 hr

• P.O. P.R.

• Ibuprofen – Advil, Motrin

• Children: 10mg/kg Q 6hr

• Adults: 200-800mg Q 6-8-12 hrs depending on what dose was given

• P.O.

Interferon

• cells infected with viruses and certain other agents produce a substance that prevents the infection of other cells, this substance is called “interferon”

• Interferon is now known to stimulate the immune system

• Is now used to boost the immune system in the treatment of malignancies and infections

Immunity

• Can be defined as the power of an individual to resist or overcome the effects of a particular disease or harmful agent

IMMUNITY

• Immunity is the final line of defense against disease

• It is a selective process meaning that immunity to one disease does not necessarily cause immunity to another

• This selective characteristic is known as “specificity”

2 Main Categories of Immunity

• 1. Inborn immunity - this is inherited along with other characteristics in a person’s genes

• 2. Acquired immunity – develops after birth, this one you “get after you are born” when you get immunizations

Inborn Immunity

• This is just like the jewish culture that gets polycthemia or the african american culture that get sickle-cell….you are born with the ability to be immune to certain things

Species immunity

• (This is a form of inborn immunity)

• Animals only have distemper, we cannot get this

• Hogs only have hog cholera, we cannot get this

• This is also how our inborn immunity works, usually, we can only get what is within out gene pool

Population Immunity

• (This is another form of inborn immunity)• Some groups have a greater inborn immunity to

certain diseases than others

• In Europe, measles is a mild disease, in the Pacific Islands, it is fatal. The foreigners brought it there. The Pacific Islanders had not yet developed a genetic resistance to the disease over time and it was too much, too fast

Polio and malaria

• In the U.S., these are public threats• American blacks were more resistant to

polio than whites, it affected white more

• Some populations are more resistant to malaria or yellow fever than are other populations

• You cannot tell who is resistant and who is not until these diseases are studied

Individual Immunity

• Herpes I - these are cold sores, some people are immune it seems and can come in contact with a cold sore and they don’t get it, others just look at it and they get one (not really)

Why do some people live longer than others

• Some 98 year old can live the perfect most healthy life for 98 yrs and never get anything really bad

• Another person may have drank, smoked, ate horribly and also has lived to be 98 yrs old…why?

• Perhaps the 2nd person had better immunity that she was born with to fight off infections and other harmful things

Acquired Immunity

• You get immune over your life time by getting 350 million cold strands and building immunity or by getting the flu shot and building immunity to that same strand

• Getting vaccinations against chicken pox, MMR so you won’t get it full blown

Acquired immunity may be…

• Active – you actually have to have contact with the disease and then you can build immunity to it. Getting a flu shot, vaccine or a cold

• Or• Passive – this is usually

passed on to a person like to a baby in mom’s breast milk. Lasts 6 months in a new born and then they build their own

Artificially acquired immunity

• Rhogam injection, mom gets it after birth, she will build it up and artificial = the injection…she didn’t make it herself

Antibody

• Is also known as an immunoglobulin

• This is found in the part of the plasma called gamma globulin

• Gamma gard or gamma globulin or IVIG is a gammaglobulin that is given to pts who need immunity such as in

• All antibodies are immunoglobulins

• There are several immunoglobulins…

Antibody

• Its purpose is to fight off the antigen using all of the body’s immunity like all of the gammaglobulins…

Antibodies

• IgG- this is given to baby by mom for general immunity

• IgA• IgD• IgM• IgE• Our body has these and they fight specific things

for example:• IgE attaches to mast cells in the resp. tract and

plays a major role in allergic reactions

IVIG, Gamma gard

• Or “gamma globulin” is a gammaglobulin that is given to pts who need immunity such as in thrombocytopenic pts, cancer pts, hepatitis A and B pts

Antigen

• Not your blood type in this case…

• This is any foreign substance that enters the body and induces or starts up an immune response

• Most antigens end up being large protein molecules, sometimes they can be carbohydrates or lipids

Antigens

• May be found on:

• the surface of pathogenic organisms

• The surface of RBC’s

• On tissue cells

• On pollens

• In toxins

• In foods

What do antigens for the body?

• They stimulate the activity of certain lymphocytes called “T” or “B” cells, which are needed in immunity and to fight the antigen off

T and B Cells

• Both come from the bone marrow

• T cells migrate to the Thymus to become mature lymphocytes

• T cells cannot recognize foreign antigens without the help if the macrophage which engulfs the foreign object and identifies it.

B cells

• Are antigen specific and will only attack certain foreign proteins

• B cells are usually found in the spleen and lymph nodes

• B cells make a picture or memory cell of the foreign protein that just entered the body so it can destroy it when it sees it again

T and B cells

• Are needed to fight foreign invaders, they will invade whatever foreign protein enters the body the 2nd time it enters

• The 1st time a foreign protein enters, pictures are taken and the next time, BOOM!!!! The body fights that protein off

Vaccines

• Can be made with live organisms, but the organism must be weakened in a lab first to take away some of the virulence. This is called “attenuated”

• Can be made with dead organisms that are killed by heat or chemicals

Recombinant DNA

• This is formulated in the lab, the genes for the specific disease are inserted into genetic material of harmless organisms.

• The antigens produced by these organisms are then extracted and purified and used for immunization

Some vaccinations

• MMR – measles-mumps-rubella• rubeola- mumps-German Measles

• Pertussis - A.K.A whooping cough

• Hepatitis B

• Varicella (chicken pox)

Rabies vaccination

• Rabies is a viral disease transmitted by the bite of wild animals such as raccoons, bats, foxes and skunks

• With this viral disease, humans ONLY get vaccinated AFTER they have been bitten

• We vaccinate out domestic pets to eliminate rabies in out pets and to us

Rabies

• There is no cure for rabies

• Rabies is fatal in almost all cases

• HOWEVER…

• The disease develops slowly so affected people vaccinated after transmission of the organism, still have time to develop an active immunity

Boosters

• Vaccinations do not last forever

• Circulating antibodies can decline with time

• Immunity needs to be replenished and booster vaccinations are given

Allergy

• Some type of irritant is exposed to the body and the body reacts to it

• Example: pollen is the antigen• An allergen is now made which is usually a

protein• When the tissues of the person are repeatedly

exposed, those tissues become sensitized (antibodies are produced in them)

• When the next invasion occurs, there is an antigen-antibody reaction

• If this takes place in the blood, there is usually no harm…if it takes place in the cells of the sensitized tissues, then the outcome can be dangerous…pt has a huge reaction

Histamine

• If an antigen is exposed and you build up antibodies, you get exposed again, huge reaction occurs:

• Histamine is released

• Dilitation of vessels occurs

• Leakage from capillaries occurs

• Contraction of involuntary muscles occurs

• ANTIHISTAMINES like benadryl are given

Autoimmunity

• Refers to the abnormal reactivity to one’s own tissues

• The body reacts to its own cells described as “self”

• Before birth, our body learns to ignore and tolerate the body’s own tissue by eliminating or inactivating those lymphocytes that will attack them

The loss of immune tolerance

• May be the reason why we have the following autoimmune diseases:

• Rheumatoid arthritis• Multiple sclerosis (MS)• Lupus• Grave’s disease• Glomerulonephritis• Juvenile diabetes

Immune Deficiency Diseases

• An immune deficiency is some failure of the immune system

• This failure of the immune system involves any part of the system such as T and B cells

• These immune diseases can be congenital (present at birth) or may acquired as a result of malnutrition, infection, or treatment with x-rays or certain drugs

AIDS

• Acquired immunodeficiency syndrome

• This infection is devastating and attacks the immune system and destroys T helper cells

• AIDS is caused by HIV – (human immunodeficiency virus)

• HIV is transmitted through unprotected sex, from mom to baby, through IV drug users.

• Blood is now tested and HIV is eliminated from blood transfusions

Secondary diseases r/t AIDS

• People can have the HIV virus for years and not have many problems

• When HIV turns to full-blown AIDS, pt’s have secondary diseases such as:

• Kaposi’s Sarcoma

Kaposi’s Sarcoma

• This is malignant skin cancer, usually seen only in AIDS pts

Pneumocystis carinii

• This is parasitic pneumonia usually seen in AIDS pts

How to treat AIDS pts

• Drugs that stop the growth of the virus at different stages of replication

• These drugs are used in combination with other drugs, can slow the progress of AIDS

The immune system and cancer

• Cancer cells differ from body cells and should be recognized as “non-self” or “as “foreign” by the immune system

• Cancer cells should be destroyed by the body but the virulence of the cancer makes this impossible

• As we age, our immune systems don’t work as well, they are not as sharp, elderly get cancer

Treatment of cancers

• Today, we use chemotherapy and radiation

• Some day we may remove T helper cells, activate them in interleukin and reinject them for success. Some melanomas have been tested this way

Transplantation and Rejection Syndrome

• Transplantation is the grafting of an organ or tissue to another or a recipient

• PROBLEM: our body spent time learning to ignore our own tissue so it won’t reject and now it sees someone else’s organ and wants to destroy it

• The donor of the organ or tissue needs to be typed and matched so this won’t happen

Typing

• Blood typing has less antigens to match than do tissue and organs

• Sometimes, we can’t find the perfect match and the pt is too sick to keep waiting so we transplant a mismatched type anyway and give anti-rejection meds such as prograf

Prograf

• Anti-rejection med that suppresses the immune reaction to the transplanted tissue

• MUST BE GIVEN AT THE SAME TIME QD in order to work effectively

Imuran

• This also suppresses the immune system

• Causes a drop in WBCs so the WBCs won’t fight against the newly transplanted organ leaving the pt open to infection

Suppressing the immune system because you just have to…

• This is a problem…

• Once you suppress the immune system, now the pt won’t reject the organ or tissue that was transplanted but what does this do for the immune system?

• It leaves no ability to fight infection…leads to septicema and could lead to death

The End