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IMMUNITY
Ch.16
What is Immunity?
 Immunity is resistance to infection after a
foreign antigen has penetrated the first line of
defense,
 Immunity is achieved naturally, by having the
disease or the artificial immunization.
 Immunity is acquired actively; that is,
intentionally by receiving a vaccine or having
had the diseases.
Cont. What is Immunity?
 It may also be acquired in a passive manner,
such as through breast milk or in vivo through
the mother’s blood supply to the fetus.
Natural and Acquired Immunities
 Natural acquired immunity – occurs when a
person has been infected with a microorganism
and recovers from the disease, has had a
subclinical or very mild infection, and/or is a
carrier of the microorganism.
 Artificial aquired immunity – results from having
been immunized, or vaccinated, with a killed or
attenuated microorganism.
 Immunities received in these instances produce
active aquired immunity.
Natural and Aquired Immunities
 Natural passive acquired immunity – is passed
from mother to child across the placenta.
 Artificially acquired passive immunity – occurs
when one receives gamma globulin, an
antitoxin, or an immune serum.
REMEMBER!!!
 Natural immunity is inherited and is
permanent.
 Acquired or adaptive immunity is the reaction
that occurs as a result of exposure to these
invaders.
 Passive aquired immunity is borrowed
immunity. It is aquired by injecting
antibodies of other individuals or animals into
a person’s body to protect him or her from a
specific disease.
Immunity’s Line of Defense
 Antibodies are produced in response to the
presence of a foreign antigen, the infectious
agent , a vaccine or an antitoxin. Antibodies
produced in the bloodstream then protect the
person against further exposure to the antigen.
 Antibodies are very specific and only act upon
their corresponding antigen.
Immunoglobulins
 Immunoglobulins are proteins that play an
important role in antibody production. There are
five classes each with a specific function
 IgG
 IgM
 IgA
 IgD
 IgE
Immunoglobulins
 IgG – is the most abundant and can cross the
placenta.
 IgM – is the largest, is confined to the blood
and functions in agglutination reactions.
 IgA – is the predominant antigen found in
tears, saliva, colostrum and intestinal
secretions.
Cont./ Immunoglobins
 IgD- works with IgM and is found on the surface
of the B lymphocytes.
 IgE – is present in trace amounts in plasma, yet
it is especially important in desensitizing allergic
reactions.
What are/is Antigens? Autoimmunity?
 Antigens are protein substances that, upon
invasion of body, cause the immune system
to produce antibodies to destroy that
antigen.
 Autoimmunity occurs when one’s immune
system goes awry and produces antibodies to
its own, destroying those tissues.
What is Hypersensitivity?
 Hypersensitivity occurs when the body’s
immune system fails to protect itself against
foreign material; thus allergies occur. Allergens
are antigens that cause allergic reactions (e.g.,
grass, ragweed, pollen, penicillin). Severe
allergic reactions can result in anaphylactic
shock and even death.
What are Toxins and Toxoids?
 Toxins are poisons produced by an organism.
 Toxoids are toxins that have been weakened by
chemicals or heat, yet are still capable of
antibody responses when injected.