CHAPTER 24

Nonspecific Defenses:Innate Immunity

Components: skin, sweat, saliva, tears,mucous membranes lining organ systems that open to the external environment—digestive/respiratory/ genitourinary, stomach acid, nose hair, cilia

24.1

Innate defensive cells:

Phagocytes: white blood cells that eat bacteria & foreign materials that enter the body

•Neutrophils: engulf microbes in infected tissue

•Macrophages: develop from monocytes & phagocytize bacteria & virus-infected cells,…they wander actively in interstitial fluid

Natural Killer Cells: attack cancer cells & virus infected cells by releasing chemicals that promote apoptosis(AKA-programmed cell death)

NOTE: All types of these white blood cells leave the blood & scavenge invading cells in the interstitial fluid & body tissues

[Not phagocytic]

Innate defense by proteins: either attack microbes directly or impede their production

Interferons: proteins produced by virus-infected cells that help other cells resist viruses (Fig. 24.1B p. 486)

Complement system: about 30 proteins that circulate in the blood plasma and work with other defense mechanisms

Inflammatory Response:

•Any damage to tissue (microorganisms or physical injury) triggers this response,… injured cells release histamine – this causes the blood vessels in vicinity to dilate & become leakier

24.2

WBC’s that rushed to the area engulf microorganisms & clean up debris

pus = dead WBCs that accumulate in area, along w/fluidsResponse to an infection may be localized or systemic

systemic – infection is widespread so more WBCs will circulate,…fever (good and/or bad) may result

Components:Lymphatic system consists of branchingnetwork of vessels, lymph nodes, thymus,tonsils, appendix, spleen, bone marrow

THE LYMPHATIC SYSTEM

24.3

Lymphatic vessels carry a fluid called lymph.

Lymphatic system has 2 main functions:

1return tissue fluid to circulatory system 2fight infections

Circulation of Lymph:

•Lymph enters system through open lymphatic capillaries

•Largest lymph ducts (R lymphatic duct & thoracic duct) empty into circulatory system’s veins in shoulders

•As lymph circulates, microbes from infected sites & cancer cells can be phagocytized by macrophages

The Immune Response

The Immune System:•When the nonspecific

defense mechanisms fail, the immune system provides another line of defense

- usually more effective than nonspecific

- can amplify certain nonspecific responses

The immune system recognizes foreign materials in the body:- foreign invaders are called antigens- can include certain molecules on the surfaces of viruses, bacteria, mold spores, cancer cells, pollen

Bacteria Bad Boys• Bacillus anthracis : anthrax • Bordetella petussis : whooping cough• Clostridium botulinum : botulism• Clostridium tetani : tetanus• Escherichia coli : acute

pyelonephritis• Lactobacillus acidophilus : cavities• Neisseria gonorrhoeae : gonorrhoea• Salmonella typhimurium : food poisoning• Streptococcus mutans : cavities• Streptococcus pneumoniae : pneumonia• Treponema pallidum : syphilis• Vibrio cholerae : cholera

•Antibody - a protein found in blood plasma that attaches to one particular kind of antigen & helps counter its effects

- antibodies do not recognize the whole antigen, only the localized region on the surface known as the antigenic determinant

-binding sites on the antibody & antigenic deter- minant have complementary shapes (lock & key)

Immunity means resistance to specificinvaders:- acquired by natural infection, or- acquired by vaccination (weakened or inactive form of the pathogen)

2 TYPES

1. Active immunity - achieved either naturally or artificially when foreign materials enter the body

2. Passive immunity - achieved when antibodies pass from mom to fetus or to a nursing newborn or when travelling (GG shots)

The Immune ResponseCells of the Immune System: Lymphocytes - WBCs that produce the immune response,…they come from stem cells in bone marrow.

-some lymphocytes continue to develop in bone marrow & become specialized B cells -others are carried by blood to thymus & become specialized as T cells -humans can have 100 million to 100 billion different B cells & T cells

B cells provide humoral immunity -B cells secrete antibodies that are carried by blood & lymph to the site of infection -this system defends against bacteria & viruses present in body fluids -can be transferred passively by plasma donation

T cells provide cell-mediated immunity-defends against bacteria, viruses, fungi, protozoans, & cancer cells inside body cells-circulate in blood & mount a cellular attack on repeated foreign invaders

•Both T & B cells must mature before they are able to function in defense of the body

- must be able to recognize & respond to a specific antigen

-must have specialized regions on their surface known as antigen receptors

•Both T & B cells will make memory cells in response to an antigen

- they are activated by a second exposure to an antigen

- seem to confer life immunity (measles, chicken pox)

The Immune Response

Humoral Immunity:

•response is mediated by the production of antibodies made by B cells

•each antibody is made of 4 polypeptide chains: 2 heavy & 2 light chains (this gives it a Y shape)

•Each of the 4 chains of the antibody has a constant (C) region:

- constant role in destroying invading cells is to mark them for destruction (opsonization)

- phagocytes will then destroy the antigen

•Variable region (V) is at the tip of each arm of the Y

•forms an antigen-binding site

Cell-mediated Immunity:

•this defense mechanism is produced by T cells & battles pathogens that have already entered body cells

•T cells do not make antibodies - they make proteins known as T cell Receptors

•When a T cell recognizes foreign antigens, they differentiate into effector cells

- cytotoxic T cells kill target cells directly

* receptors on the T cells recognize antigenic determinants on the target

* target cell will then be lysed

* T cells may also attack cancer cells & prevent them from spreading

•Helper T cells: (many roles)- help activate cytotoxic T cells & macrophages- help stimulate B cells to make antibodies

- interact w/other WBCs that function as antigen-presenting cells (APCs) - these cells present a foreign antigen to the helper T cell

Self from Nonself(Blood Types)

•For each blood type there is an antigen present on the surface of the RBC

- Type O has no antigens - Type A has antigen A - Type B has antigen B - Type AB has antigens A & B

•Blood types w/antigens on the surface do not have antibodies against that antigen

•another blood group

antigen is the Rh factor

- antibodies produced by mom can react w/blood of fetus - problems when Rh(-) mom produces antibodies against Rh(+) fetus

1.Platelets are joined w/fibrinogen

2.Fibrin forms

3. Clots form(Our bodies respond to antigens)

Major Histocompatibility Complex

•Ability to distinguish self from nonself (MHC)

•acts as your biochemical finger-print: it is 2 sets of self proteins on surfaces of our cells

•this complex must be considered before any kind of transplant is done

Immunological Malfunction•Autoimmune disease - when the

immune system turns against its own body

- lupus, rheumatoid arthritis, scleroderma

Lupus,…people develop immune reactions against their own nucleic acids; deposits of antibody-nucleic acid complexes accumulate causing inflamed joints & kidney

Immunodeficiency diseases cause part or all of the immune system to be lacking

-Hodgkin’s Disease is a lymphocyte cancer

-Severe Combined Immunodeficiency (SCID) is when both B & T cells are lacking or inactive (sensitivity to minorinfections)

•Allergies are overreactions to certain environmental antigens

- these antigens are called allergens (dust, pollen, insect toxins, cat saliva)

- allergic reactions are usually rapid & occur in nasal passages, skin, bronchi

-antibodies trigger allergic reactions by binding to,… mast cells: noncirculating cells located in connective tissue -the antibody & mast cell combo binds to an antigen

Mast cells Basophils T lymphocytes Neutrophils Eosinophils

Histamine Tryptase Prostoglandins Leukotrienes Cytokines Chemokines

* mast cells release histamine (causes sneezing, itchiness of skin, tearing of eyes)

* this process is called degranulation

* an antihistamine is a drug that interferes w/the actions of the histamine

Anaphylactic shock is a dangerous type of allergic reaction-extremely allergic to things like bee stings, mosquitoes,etc.-blood vessel will dilate abruptly, causing a drop in blood pressure (shock)

What do you know about AIDS?

1.When was it first diagnosed in the U.S.?

2. What do AIDS patients die from?

3. What is HIV?

1981

Secondary infections,…Ex-Pneumonia, cancer, etc.

Human Immunodeficiency Virus

4. What does the acronym AIDS stand for?

5. When does HIV become AIDS?

Acquired Immuno-Deficiency Syndrome

When the body is no longer ableto fight off infections that a normalimmune system could defend against.

6. True or False: Blood transfusion patients are at high risk of acquiring HIV.

7. Who is predominantly diagnosed with AIDS?

FALSE

Anyone having promiscuous sexis at risk. IV needleswith drug use.

(HIV virus)

8. Which countries are at high risk for AIDS?

9. True or False: The number of new HIV diagnosed patients in Illinois has decreased.

10. What is the best way to decrease or eliminate HIV?

Africa as a whole,…andHaiti, Thailand,…poorer, uneducated

FALSE

Don’t have sex

AIDS• Acquired Immune Deficiency

Syndrome• since 1981, more than 60 million

people worldwide have been infected w/the AIDS virus HIV

• since 1981, more than 25 million people worldwide have died from AIDS related causes

• 33.4 million people worldwide are living with HIV

• 5 million new cases of HIV were reported in 2004

Your Area

•New cases of HIV in Illinois:* 2004 – 1,410

* 2005 – 1,366•St. Louis area: *2003: 2,312 HIV 4,717 AIDS

Estimate Range

People living with HIV/AIDS in 200833.4

million31.1-35.8

million

Adults living with HIV/AIDS in 200831.3

million29.2-33.7

million

Women living with HIV/AIDS in 200815.7

million14.2-17.2

million

Children living with HIV/AIDS in 2008 2.1 million 1.2-2.9 million

People newly infected with HIV in 2008 2.7 million 2.4-3.0 million

Children newly infected with HIV in 2008

0.43 million

0.24-0.61 million

AIDS deaths in 2008 2.0 million 1.7-2.4 million

Child AIDS deaths in 20080.28

million0.15-0.41

million

http://www.avert.org/worldstats.htm

http://www.until.org/statisticshttp://www.idph.state.il.us/aids

•Affects a variety of cells - preferring the helper T cells, causing no cell-mediated or humoral response

•death usually results, not from AIDS, but another infectious agent or cancer