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Specific Immunity
 Innate Immunity: Immunity present at birth
 Adaptive Immunity: immunity developed during life
 Specific immunity comes in to play when a pathogen
has breached the first and second line of defense
 1st line (skin, mucous membranes, acid)
 2nd line (phagocytes, inflammatory response,
interferons, complement system)
Identification MHC
 Body cells recognized as self
 Invading pathogens are recognized as non self
 MHC: major histocompatibility complex
 Group of cell surface molecular protein markers
 Found on surface of all nucleated cells (except RBC’s)
 Unique to each individual (except identical twins)
 2 types
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Located on immune cells
Located on nucleated body cells
Lymphocyte Review
 B-cells
 Originate and fully mature in bone marrow
 Destroy any free pathogen (not inside a cell)
 T-cells
 Originate in bone marrow but mature in the thymus
 Destroy any body cells infected with pathogens and
cancerous cells
Cell-Mediated and Humoral Immunity
Feature
Humoral immunity
Cell-mediate immunity
Lymphocytes involved
B-cells
T-Cells
Effector cells
Plasma cells
Cytotoxic T-Cells
Target/function
Destroys all free antigens
(not inside of cells)
Destroys all infected cells,
multicellular pathogens
and cancerous cells
Mode of action
Plasma cells produce
antibodies that surround
and neutralize the
pathogen
Cytotoxic T-cells release
chemicals that trigger
apoptosis of the infected
cell
Clonal Selection
 Activated B cells multiply to form a clone of plasma
cells and memory cells
 Large number of plasma cells that produce one specific
antibody
 Activation of humoral response triggers existing B-
cells to give rise to effector cells (plasma cells) and
memory cells
 Plasma cells develop from activated B-cells and produce
antibodies
 Cell-mediated response initiated at same time as
humoral response
 Activates cytotoxic T-cells and memory cells
Humoral & Cell mediated immunity
The Role of Antibodies
 Opsonization: make pathogens more recognizable to




phagocytes
Neutralization of viruses and bacteria
Neutralization of toxins
Activation of complement (causes cell to lyse)
Agglutination (sticking together)
Review of Immune response
 Challenge: body is invaded by pathogens
 Response: Helper T-cells are alerted to the presence of
a pathogen.
 Clonal selection: Only those B-cells and T-cells that
are specific to the antigen are activated
 Memory cells: produced to be ready to destroy any
subsequent invasion by the same pathogen
Active & Passive Immunity
Type
Response
Active natural immunity
Naturally obtaining the antigen from the
environment (saliva)
Active artificial immunity
Organism artificially obtaining the antigen from the
environment(vaccination)
Passive natural immunity
Results from receiving antibodies du to natural
processes (breastfeeding)
Passive artificial immunity Receiving antibodies due to artificial antibodies
(injections of antibodies)
Antibodies
 Antibodies (immunoglobins)
 Are Y shaped
 Globular proteins
 Produced by plasma cells
 Destroy antigens by surrounding them
Monoclonal antibody production
 Uses biotechnology
 Mass production of an antibody specific to any desired
antigen
 Steps
 Antibody injected into a rodent with selected antigen
 Spleen removed
 B-cells removed from spleen
 B-cells fused with cancer cells to produce hybridomas
 Hybridomas divide indefinitely and produce antibodies
 Hybridomas can be used for diagnosis and treatment
Monoclonal
 Diagnostic use
 Detection of HIV antibodies
 Detection of cardiac enzymes (signal heart attack)
 HCG pregnancy
 Treatment use
 Targeting cancer cells with chemo
 Emergency treatments of rabies
 Tissue typing for transplant compatibility
The Principle of Vaccination
 The goal of a vaccine is to trigger a primary immune
response that results in the production of memory
cells
 Weakened form of the pathogen is injected or inhaled
 Allows immune system to recognize and destroy antigen
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
Normal response 5-10 days
Vaccine response 3-5 days
Primary and secondary antibody production
Benefits & Dangers of Vaccines
 Benefits
 Eliminate disease (smallpox)
 Prevent serious side effects
 Less medical costs
 Prevent pandemics and epidemics
 Dangers
 Allergic reactions
 Injection site could become infected
 Rare cases of neurological issues
Allergies
 When immune system response with an exaggerated
immune response to harmless antigens
 Food
 pollen
 Release of histamines (trigger)
 Constriction of smooth muscle (breathing problems)
 Increasing permeability of capillaries (swelling)