all immune cells come from
bone marrow
B-cells are activated in
spleen and lymph nodes
T-cells mature in
thymus
tonsils and adenoids are examples of
gut-associated lymphoid tissue
leukocytes
Cells of the immune system involved in protecting body against infectious disease and foreign invaders.
All white blood cells derived from a multipotent cell in the bone marrow known as a hematopoietic stem cell. Leukocytes are found throughout the body, including the blood and lymphatic system.
skin
physical barrier and secretes antimicrobial compounds like defensins
mucous
on mucous membranes traps pathogens; in respiratory system, mucous is propelled upward by cilia and can be swallowed or expelled
tears and saliva contain
lysozyme, an antibacterial compound
defenses of gut
stomach produces acid, which kills most pathogens. colonization of gut helps prevent outgrowth by pathogenic bacteria through competition
complement system
can punch holes in cell walls of bacteria to make them osmotically unstable
interferons
given off by virally infected cells and help prevent viral replication and dispersion to nearby cells
macrophages
ingest pathogens and present them on major histocompatibiltiy complex (MHC) molecules. they also secrete cytokines
MHC-I
present in all nucleated cells. present endogenous antigen (proteins from within the cell) to cytotoxic T-cells (CD8+ cells)
MHC-II
present in professional antigen-presenting cells (macropahges, dendritic cells, some B-cells, and certain activated epithelial cells) and display exogenous antigen (proteins from outside the cell) to helper T-cells (CD4+ cells)
dendritic cells
antigen-presenting cells in the skin
natural killer cells
attack cells not presenting MHC molecules, including virally infected cells and cancer cells
granulocytes
include neutrophils, eosinophils, basophils
neutrophils
ingest bacteria, particularly opsonized bacteria (those marked with antibody). they can follow bacteria using chemotaxis.
eosinophils
used in allergic reactions and invasive parasitic infections. they release histamine, causing an inflammatory response.
basophils
used in allergic reactions. mast cells are related cells found in the skin
humoral immunity
centered on antibody production by plasma cells, which are activated B-cells
when activated, antigen-binding region undergoes
hypermutation to improve specificity of antibody produced. cells may be given signals to switch isotypes of antibody (IgM, IgD, IgG, IgE, IgA)
circulating antibodies can
opsonize pathogens (mark them for destruction), cause agglutination (clumping) into insoluble complexes that are ingested by phagocytes, or neutralize pathogens
cell-surface antibodies
can activate immune cells or mediate allergic reactions
memory b-cells
lie in wait for a second exposure to a pathogen and can then mount a more rapid and vigorous immune response (secondary response)
cell-mediated immunity is also called
cytotoxic immunity
cell-mediated immunity is centered on the functions of
T-cells
T-cells undergo maturation in
the thymus through positive and negative selection. the peptide hormone thymosin promotes T-cell development.
positive selection
only selecting for T-cells that can react to antigen presented on MHC
negative selection
causing apoptosis in self-reactive T-cells
helper T-cells also called
Th or CD4+
helper T-cells
respond to antigen on MHC-II and coordinate the rest of the immune system, secreting lymphokines to activate various arms of immune defense. Th1 cells secrete interferon gamma, which activates macrophages. Th2 cells activate B-cells, primarily in parasitic infections
cytotoxic t-cells also called
Tc, CTL, CD8+
cytotoxic T-cells
respond to antigen on MHC-I and kill virally infected cells
suppressor T-cells also called
regulatory
suppressor T-cells
tone down the immune response after an infection and promote self-tolerance
memory T-cells
serve a similar function to memory B-cells
in allergic reaction
nonthreatening exposures incite an inflammatory response
passive immunity
transfer of antibodies
active immunity
activation of B-cells that produce antibodies to an antigen
lymphatic system
circulatory system that consists of one-way vessels with intermittent lymph nodes
the lymphatic system connects
to the cardiovascular system via the thoracic duct in teh posterior chest
the lymphatic system accomplishes
equalizes fluid distribution, transports fats and fat-soluble compounds in chylomicrons, and provides sites for mounting immune responses