IMMUNOSERO // STEVENS CHAP 1: INTRO TO IMMUNITY AND THE IMMUNE SYSTEM Flashcards
The study of a host’s reactions when foreign substances are introduced into the body
Immunology
Roots in the study of immunity
Immunology
the condition of being resistant to infection
Immunity
Foreign substances that induce a host response
Antigens
All around in nature from pollen to serious bacterial pathogens
Antigens
serum proteins produced by certain lymphocytes when exposed to Ag and react specifically
Antibodies
The individual’s ability to resist infection by means of normally present body functions.
Innate Immunity/Natural Immunity
Considered nonadaptive or nonspecific; the same for all pathogens or substances to which one is exposed
Innate Immunity/Natural Immunity
NO prior exposure is required
Innate Immunity/Natural Immunity
Lacks memory and specificity
Innate Immunity/Natural Immunity
Characterized by specificity for each individual pathogen and the ability to remember a prior exposure
Adaptive Immunity
result in an increased response to that pathogen upon repeated exposure
Memory and specificity
play a key role in both innate and adaptive immunity
LEUKOCYTES IN PERIPHERAL BLOOD
All blood cells: arise from a type of cell called a
hematopoietic stem cell (HSC)
To form WBCs: the HSC gives rise to 2 distinct types of precursor cells:
common myeloid precursors
common lymphoid precursors
WBCs that participate in phagocytosis (myeloid line)
common myeloid precursors
lymphocytes; form the basis of the adaptive immune response
common lymphoid precursors
has 2 to 5 lobes
NEUTROPHILS
Contain a large number of when stained with Wright stain
NEUTROPHILS
Main function of neutrophils
phagocytosis
Contain antimicrobial products such as: myeloperoxidase, lysozyme, elastase, proteinase-3, cathepsin G,
and defensins, which are small proteins that have antibacterial activity
Azurophilic/Primary Granules
Contain lysozyme, lactoferrin, collagenase, gelatinase, and respiratory burst components
Specific/Secondary Granules
Half of total NEUT pop. in peripheral blood: found in a ________ adhering to blood vessel walls
marginating pool
Occurs to allow neutrophils to move from the circulating blood toàtissues through a process known as diapedesis, or movement through blood vessel walls; Attracted to a specific area by chemotactic factors
Margination
Chemical messengers that cause cells to migrate in a particular direction
Chemotaxins
Approx. 1% to 3% of circulating WBCs in a nonallergic person; 12 to 15 um
EOSINOPHILS
Nucleus: usually bilobed/ellipsoidal and is often eccentrically located
EOSINOPHILS
Increases in: allergic reaction or in response to certain parasitic infections
Eosinophils
Take up the acid eosin dye and the cytoplasm is filled with large orange to reddish-orange granules
Eosinophils
Able to neutralize basophil and mast cell products
Eosinophil
Most important role: regulation of the immune response, including regulation of mast cell function
Eosinophil
damage cell membranes and kill larger parasites that cannot be phagocytized
Cationic proteins
The least numerous of WBCs; less than 1%; Smallest of the granulocytes; slightly larger than RBCs
BASOPHILS
Contain coarse, densely staining deep-bluish-purple granules that often obscure the nucleus
BASOPHILS
Regulate some T helper cell responses
BASOPHILS
Stimulate B cells to produce the antibody IgE
BASOPHILS
Life span: short life span of in the bloodstream; they are then pulled out and destroyed by macrophages in the spleen.
BASOPHILS
Contains histamine, cytokines, growth factors, and a small amount of heparin
Granules in Baso
All of which have an important function in inducing and maintaining allergic reactions
Basophil
contracts smooth muscle
Histamine
Largest cells in p. blood; 12 to 22 um (ave of 18um)
MONOCYTES
Distinguishing feature: irregularly folded or horseshoe-shaped nucleus that occupies almost one half of cell
MONOCYTES
Abundant cytoplasm stains dull grayish blue and has ground-glass appearance bc of fine dustlike granules
MONOCYTES
Make up 4% to 10% of total circulating WBCs.
MONOCYTES
They do not remain in the circulation for long. They stay in peripheral blood for up to 30hrs; they then migrate to the tissues and become known as macrophages.
MONOCYTES
Macrophages in the lungs
Alveolar macrophages
Macrophages in the liver
Kupffer cells
Macrophages in the brain
Microglial cells
Macrophages in the bone
Osteoclasts
Macrophages in connective tissue
Histiocytes
Important role: in initiating and regulating both innate and adaptive immune responses
Macrophages
Presenting antigens to T and B cells
Macrophages
The (antigen-presenting cell) in the body & the cell
DENDRITIC CELLS
Dendritic cells are discovered by
Steinman and Cohn in 1973
After capturing an antigen in the tissue by phagocytosis or endocytosis, _______ present the antigen to T lymphocytes to initiate the adaptive immune response in a similar way as macrophages
dendritic cells
The key cell involved in adaptive immune response; 20% to 40% of circulating WBCs
Lymphocyte
proteins/antigens on cell surfaces used to identify each lymphocyte subpopulation in the lab
Clusters of Differentiation (CD)
Found on all T cells; associated with t-cell antigen receptor
CD3
Identifies t helper cells; also found on most T regulatory cells
CD4
Identifies cytotoxic T cells
CD8
Low affinity fc receptor for antibody; mediates phagocytosis
CD16
Part of b-cell coreceptor; regulates b-cell development and activation
CD19
Receptor for complement component C3d; part of b-cell coreceptor with CD19
CD21
Derived from a lymphoid precursor that differentiates to become either a T cell, B cell, or NK cell depending on exposure to different cytokines
B CELLS
Can be recognized by the presence of membrane-bound antibodies of two types: IgM and IgD
B CELLS
Other surface proteins of B cells include:
CD 19, CD21, and class II MHC molecules
Lymphocyte precursors called _______ enter the thymus from the bone marrow thru the bloodstream
thymocytes
Produce cytokines that contribute to immunity by stimulating B cells to produce antibodies
T CELLS
3 main subtypes of T cells
Helper (CD4)
Cytolytic (CD8+)
Regulatory (CD4)
Ratio of CD4+ to CD8+ cells
2:1 in peripheral blood
A small percentage of lymphocytes do not express the markers of either T cells or B cells
NATURAL KILLER (NK) CELLS
So named bc have ability to kill target cells w/o prior exposure to them
NATURAL KILLER (NK) CELLS
DO NOT require the thymus for development but appear to mature in bone marrow itself
NATURAL KILLER (NK) CELLS
generally larger than T cells and B cells at approx. 15um in diameter and contain kidney-shaped nuclei with condensed chromatin and prominent nucleoli; make up 10% to 15%
NATURAL KILLER (NK) CELLS
Nk cells are found mainly in the
liver, spleen, and peripheral blood
specific combination of Ag that can be used for identification
CD16 & CD 56
a receptor for nonspecific end of antibodies; bc of its presence, NK cells are able to make contact with and then lyse any cell coated with antibodies
CD 16
are also capable of recognizing any foreign cell and represent the 1st line of defense against virally infected cells and tumor cells
NK cells
Half-like of NK cells
7 to 10 days
Also have the capability to develop memory to specific antigens in a similar manner to T cells.
NATURAL KILLER (NK) CELLS
Important role as a transitional cell bridging the innate and adaptive immune response against pathogens
NATURAL KILLER (NK) CELLS
largest lymphatic vessel in the body; collects most of the body’s lymph fluid and empties it
into the left subclavian vein.
Thoracic duct
majority of circulating lymphocytes; effector cells that serve a regulatory role
T cells
gives rise to long-lived memory cells and shorter-lived effector cells that are
responsible for the generation of the immune response
Antigen activation
Where lymphocytes and any foreign antigens present enter the nodes
Afferent lymphatic vessels
Where lymphocytes and any foreign antigens present exit the nodes
Efferent lymphatic vessels
Accumulation of lymphocytes and other cells that causes the lymph nodes to become enlarged
Lymphadenopathy
Differentiate into memory cells & plasma cells; Responsible for humoral immunity or antibody formation
B cells
Responsible for cell-mediated immunity; Produce sensitized lymphocytes that secrete cytokines
T cells