2.2.1.  fast-acting white blood cells (neutrophils (26-2), eosinophils, and basophils)

	neutrophils - most abundant, phagocytize bacteria
	eosinophils - secrete enzymes that enhance destruction of antigens
	basophils and mast cells - secrete histamine and other substances to keep inflammation going
	macrophages - digest any particles; slower acting

2.2.2.  complement proteins (26-3)

	blood-clotting proteins, and other infection-fighting substances
	prepare antigens for destruction by white blood cells

2.2.3.  organs with pathogen-killing functions (e.g. lymph nodes)

	white blood cells (macrophages, B cells, T cells)
	communication signals (e.g. interleukins) and other chemical weapons (e.g., antibodies, perforins)

	antigens are always large molecules, usually proteins or polysaccharides
	may be free in solution or built into surfaces of particles like bacteria or pollen

2.5.2.   cell-mediated

	involves specialized cells attack antigens directly
	regulates activity of humoral system (26-4)

3. Lymphocytes

3.3.1.  Has thousands of antibody molecules mounted in its cell membrane

	composed of heavy and light chains (26-5)
	binds to two specific antigen molecules (26-6)

3.3.2.   Engulfs bound antigens and digests into smaller fragments

3.3.3.  Stimulated B-cell (26-7) produces numerous plasma cells which are antibody factories which secret antibodies identical to those on the surface.

these circulate freely in blood and lymph and attack antigens

3.3.4.  Stimulated B-cell also produces memory cells which are lymphocytes like itself

these remain in circulation for months and "remember" the antigen during future exposure.

3.3.5.  Agglutination (clumping) of antibodies bound to antigens (26-8)

	easier for large phagocytic macrophages in lymph to recognize bound antigens (26-9)
	NK (natural killer) lymphocytes recognize bound antibodies, bind to them, and secrete powerful chemicals to destroy them
	bound antibodies trigger enzymatic reactions (complement cascade) the leads to cell lysis

3.4.  T-Lymphocytes Control the Cell-Mediated Immune Response

3.4.2.  T-cell receptors (26-10)

	are not secreted but stick to lymphocyte
	recognize and bind to only one antigen molecule
	for recognition, antigen must be bound to special marker protein (major histocompatibility complex, MHC) and presented to the T-cell by a special antigen-presenting cell.

3.4.3.  Two types of MHC proteins

	MHC-II - found on membranes of b cells, cytotoxic T cells and macrophages
	MHC-I - found on membranes of all other cells of the body
	Structure and function of MHC molecules (a) (26-11) (b) (26-12) (c) (26-13)

3.4.4.  Summary of cell-mediated immune responce (26-14)

	Beta cells (26-15)
	T Cells (26-16)

3.4.5.  Viral infection (26-17)

	antigens of virus attach to MCH-I proteins
	T-cells bind to antigen- MCH-I complex
	T-cells replicate producing memory T cells, Helper T-cells, Suppresser T cell, and Cytotoxic T-cells helper T-cells produce cytokines that activate other cells of the immune system (macrophages and other B and T cells); they also stimulate antigen bound B-Cells to divide and produce antibodies. suppresser T-cells inhibit activity of macrophages and other lymphocytes; they stop the immune response when no longer needed. cytotoxic T-cells search out abnormal cells (such as cancer cells or virus-infected cells) and destroy them

3.4.6.  Bacterial Infection (26-18)

	produces large numbers of lymphocytes specific for a particular antigen
	within a week or to billions of specific antibody lymphocytes are synthesized for action
	clonal selection of B cell (26-20)
	immunological memory (26-21)
	primary and secondary exposure to antigen (26-22)

	antibody response is slow
	body must rely on non-specific defenses
	memory cells confer a relatively long-lasting immunity

patient is exposed to antigen to confer immune response

patient is exposed to antiserum containing antibodies

	The body can't recognize itself and antibodies begin destroying its own cells
	Myasthenis Gravis - loss of body's tolerence to acetyl choline; affects interactions of nerves and muscles.
	System Lupus Eythematosus - T cells attack the skin, kidneys, and other organs.
	Rheumatoid Arthritis - T cells attack the linings of joints.
	Multiple Sclerosis - T cells attack the cells of brain and spinal cord.
	Acquired Immune Deficiency Sysdrome - an RNA virus carries the enzyme reverse transcriptase which makes a cDNA copy of the virus and inserts it into host DNA, mainaly in T4 lympcytes. It may remain dormant for several years (about 8) after which it begins replicating and destroying T4 cells and comprimizing the immune system of the infected person. Secondary infections developed resulting in severy illness and death.

	Allergens (such as pollen) enter the body and stimulate B cells that have the appropriate receptors.
	The stimulated B cells mature into plasma cells and begin secreting a special class of antibodies, IgE antibodies.
	The IeG antibodies attach to receptors on the surfaces of mast cells.
	When the allergen is introduced again, the binding of the allergens to the mounted IgE antibodies causes the mast cell to release histamine and other chemicals that produce the symptoms of allergy. These chemicals cause itchy, reddened areas caused by outpouring of plasma from the blood and vasodilation which can cause drop in blood pressure.