NOTES: CH 43, part 2 - Immunity in Health and Disease

PRIMARY IMMUNE RESPONSE

● PRIMARY IMMUNE RESPONSE: the first reaction / response to an antigen (first exposure)

during this response, antibodies are produced for several weeks

antibodies first show up within 5-10 days

some B cells remain dormant as MEMORY CELLS

SECONDARY IMMUNE RESPONSE

● SECONDARY IMMUNE RESPONSE: the second response (exposure) to an antigen

rapid response due to memory cells produced during the first exposure

antibodies produced within a day or two

CLASSIFICATION OF IMMUNITY

1) ACTIVE IMMUNITY

● when the person produces an immune response (including memory cells) to the antigen

● a result of direct exposure to the antigen

● long-lasting (memory cells)

ACTIVE IMMUNITY…

NATURALLY ACQUIRED ACTIVE IMMUNITY: person is directly exposed to the pathogen, develops a disease, and acquires immunity

ARTIFICIALLY ACQUIRED ACTIVE IMMUNITY: person receives a vaccine

VACCINES…**A VACCINE consists of bacteria or

viruses that have been weakened or killed so they a cannot cause a serious infection; or could include a toxin that has been chemically altered to destroy its toxic effects

-includes antigens that stimulate a primary immune response but does not produce the severe symptoms of disease

2) PASSIVE IMMUNITY

● person receives antibodies

produced by another

individual

● since the person does not produce the immune response themselves, this is short-term only (as long as the antibodies remain in the blood)

● the person remains vulnerable to the antigen if exposed at a later date

PASSIVE IMMUNITYNATURALLY ACQUIRED

PASSIVE IMMUNITY: fetus acquires limited immunity from mother through placenta and/or breast milk (colostrum)

ARTIFICIALLY ACQUIRED PASSIVE IMMUNITY: person receives an injection of antiserum collected from a person who has already developed immunity against a particular disease

ALLERGIC REACTIONS● excessive and misdirected

immune responses that may damage tissue

● triggered by antigens known as ALLERGENS

● the immune system attacks a nonharmful substance, such as chocolate

ALLERGIC REACTIONS1) Delayed-reaction allergy: results from repeated

exposure of the skin to certain chemicals (e.g. household chemicals, cosmetics)

● T cells and macrophages collect and release chemicals that cause

eruptions and

inflammation

(DERMATITIS)

● “delayed” because it takes

about 48 hours to

develop

ALLERGIC REACTIONS2) Immediate-reaction

allergy: an inborn ability to overproduce IgE antibodies in response to certain antigens/allergens

(i.e. pollen, pet dander, etc.)

● occurs within minutes of contact with allergen

Immediate-reaction allergy results from mast cells bursting and

releasing allergy chemicals such as HISTAMINE

causes blood vessels to dilate, tissues swell, contraction of bronchial and intestinal smooth muscles, increased mucus production

the released chemicals cause allergy symptoms such as: hives, hay fever, asthma, eczema, or gastric disturbances

Extreme allergies…

**severe example of immediate-reaction allergy: ANAPHYLACTIC SHOCK!

● mast cells throughout the body release histamine

● severe drop in blood pressure (could lose consciousness and possibly die)

● person must receive an injection of epinephrine (adrenaline) to restore blood pressure

TRANSPLANTATION and TISSUE REJECTION

● TISSUE REJECTION REACTION: when a transplant recipient’s immune system reacts against the donated tissue/organ

● to minimize tissue rejection:

match donor and recipient tissues

use immunosuppressive drugs (help with transplant acceptance, but may increase the recipient’s risk of infection)

                                                      

AUTOIMMUNITY / AUTOIMMUNE DISORDERS:

● the immune system manufactures AUTOANTIBODIES (antibodies that attack a person’s own body tissues)

● may result from a previous viral infection, faulty T-cell development, or reaction to a nonself antigen that resembles a self antigen

 Examples of Autoimmune Disorders:

Lupus erythematous

Rheumatoid arthritis

Insulin-dependent diabetes

Multiple sclerosis

Heart valve damage

Grave’s disease

Rheumatic fever

Immunodeficiency disease: affected individual is deficient in either humoral or cell-mediated immune defenses

Examples:

SCID

Hodgkin’s lymphoma

some viral infections (e.g. AIDS)

physical / emotional stress can compromise immune system

AIDS

caused by retrovirus: HIV

affected individuals are highly susceptible to opportunistic diseases, infections, cancers

two major strains: HIV-1 and HIV-2

HIV infects TH cells, which carry CD-4

receptors on other surface

*HIV-positive = tests positive for presence of HIV-antibodies

 

*AIDS = late stage of HIV infection

-defined by reduced T-cell population

-appearance of secondary infections

-takes average of 10 years to reach this stage

-viral load also good indicator

Secondary Infections

Transmission of HIV: transfer of body fluids: blood, semen most commonly via unprotected sex

and unsterilized needles transmission during fetal development

occurs in 25% of HIV-infected mothers

blood transfusions (decline in incidence with screening procedures)

Drug therapies include:

DNA-synthesis inhibitors reverse transcriptase inhibitors (e.g.

AZT) protease inhibitors drugs to fight opportunistic infections

(helps ease symptoms of secondary infections)