The Adaptive (Specific) Immune System (Chapter 18)
• Adaptive immunity: defenses that target a specific pathogen
o Learned- the body has to adapt to this
o Some pathogens change their shape so that adaptive immunity m
...
The Adaptive (Specific) Immune System (Chapter 18)
• Adaptive immunity: defenses that target a specific pathogen
o Learned- the body has to adapt to this
o Some pathogens change their shape so that adaptive immunity misses them
• Acquired through infection or vaccination
o Immune response is always stronger through infection
• Primary response: first time the immune system combats a particular foreign substance
• Secondary response: later interactions with the same foreign substance; faster and more effective due to “memory”
Dual Nature of the Adaptive Immune System
1. Humoral immunity
. Produces antibodies that combat foreign molecules known as antigens
. Antibodies are made by a type of B cell lymphocyte (white blood cell)
. Named for the bursa of Fabricius in birds
. Humoral immunity fights invaders outside cells
. Bacteria and toxins for example
. Done in lymph (done in blood)
. Antibodies are secreted all over the body
. Lymph, blood, saliva, milk, line the digestive system
2. Cellular Immunity (cell-mediated immunity)
. Does not make antibodies
. Produces T cell lymphocytes (white blood cells)
. Mature in the thymus
. Attack antigen inside of cells
. Antibodies cannot get inside of cells
. Release chemicals that kill infected cells
Cytokines: Chemical Messengers of Immune Cells
• Cytokines are chemical messengers produced in response to a stimulus
o Examples:
Interleukins: cytokines between leukocytes
Chemokines: induce migration of leukocytes
Interferons (IFNs): interfere with viral infections of host cells
Tumor necrosis factor (TNF): involved in the inflammation of autoimmune diseases
Hematopoietic cytokines: control stem cells that develop into red and white blood cells
Overproduction of cytokines lead to a cytokine storm
• Function of cytokines? Chemicals from white blood cells that activate the immune system
Antigens
• Antigens: substances that cause the production of antibodies
• Usually components of invading microbes or foreign substances
• Haptens: antigens too small to provoke immune responses; attach to carrier molecules to become antigenic (many allergens are considered haptens)
Antibodies
• ANTIBODIES ARE MADE OF PROTEIN
• Globular proteins called immunoglobulins (Ig)
• Made by B cells
Generating Antibody-Producing Cells:
• Inactive B cells contain surface antibody (membrane-bound antibody) that bind to antigen
Clonal Selection of Antibody-Producing Cells
• Clonal selection differentiates activated B cells into:
o Antibody-producing plasma cells
Plasma Cell
• Secretes antibody
• Short life span
o Hours maybe days
o Memory cells
Produce lots of antibodies in a short time
Long life span
• Can be months, years, or whole life depending on the particular memory cell
Memory cell is all about your secondary exposure
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