Immune System Flashcards
Innate (nonspecific) system
Respond quickly And consists ofFirst and second line of defense
First line of defense
Innate
Skin and mucosa prevent Entry of microorganisms “don’t let em in”
Physical- keratin
Chemical- salt, Hcl, lysosomes, dermicidin
Second line of defense
Innate
Anti-microbial proteins phagocytes and other cells
Inhibit spread of invaders throughout the body
Inflammation is it’s most important mechanism
Cells and chemicals are nonspecific
Adaptive (specific) defense system
Third line of defense mount an attack against particular foreign substances Takes longer to react than the innate Works in conjunction with the innate T cells and B cells
Nonspecific cellular & chemical devices
Phagocytes and natural killer (NK) cells
Antimicrobial proteins in blood and tissue fluid
inflammatory response enlists macrophages, mast cells , WBCs and chemicals
Mechanisms of phagocytosis
- Microbes adhere to the phagocyte
- Pseudopods engulf the particular antigen into a phagosome
- phagosomes fuse with a lysosome to form a phagolysosome
- Invaders in the phagolysosome are digested by proteolytic enzymes
- Indigestible and residual material is removed by exocytosis
Phagocytic mobilization
4 steps
- Leukocytosis- neutrophils are released from bone marrow in response to leukocytosis inducing factors released by injured cells
- Margination- Neutrophils cling to the walls of capillaries in the injured area
- Diapedesis- Neutrophils squeeze through capillary walls and begin phagocytosis
- Chemotaxis- Inflammatory chemicals attract neutrophils to the injury site
Inflammation
Triggered when body tissues are injured, prevents spread of damaging agents to nearby tissue, disposes all debris and pathogens, sets stage for repair processes
Four cardinal signs of inflammation
Calor- heat
Rubor- redness
Tumor- swelling
Dolor- pain at site
Exudate
Fluid containing proteins, clotting factors and antibodies
exudates seeps into tissue spaces causing local edema, which contributes to the sensation of pain
Fixed macrophages
Kupffer cells (liver)
Microglia (brain)
Langerhans (skin)
Chief phagocytic cell
Macrophage
Edema
The surge of protein rich fluids into tissue spaces
Help dilute harmful substances
brings in large quantities of oxygen and nutrients needed for repair
Allows entry of clotting proteins which prevent the spread of bacteria
Pus
Material in severely infected area dead/dying neutrophils Broken down tissue dead/living pathogens if not cleared out abscess can occur
Infectious granuloma
Tumor like growth that contains a central region of infected macrophages.
bacteria survive and can break out when persons resistance is compromised
The most important antimicrobial proteins are
Interferon
complement proteins
Interferon
Interferes with viral replication
Leave infected cell enter neighbor cell and activates genes for antiviral proteins
Also activate macrophages and mobilize NKs
Complement
Enhances or complements immune response
- Inflammatory response- stimulates mast cells & basophils to release histamine
- Opsonization: coats bacteria w/ opsonins make them more tasty for phagocytes
- MAC membrane attack complex- coats bacteria creates holes in membrane
What is the body’s thermostat
Hypothalamus
Adaptive (specific) defenses
Adaptive immune system includes the antibodies
It is specific
Systemic
Has a memory
Humoral immunity
Antibodies circulate through the blood and lymph and bind to invaders to inactivate them and mark them for destruction
Cell-mediated immunity
Lymphocyte themselves, rather than antibodies, kill invaders directly or indirectly with chemical mediators
Antigen
Substances that mobilize immune system and provoke an immune response
Nonself
Ultimate targets of all immune responses are mostly large, complex molecules, not normally found in the body
Immunogenicity
Ability to stimulate proliferation of specific lymphocytes and antibody production
Reactivity
Ability to react with products of activated lymphocytes in the antibodies released in response to them
Which is the strongest antigen?
Protein
Complete antigen
When the whole thing is an antigen
properties: immunogenicity and reactivity
example: foreign proteins, nucleic acid, some lipids, polysaccharides
Haptens
Incomplete antigen
Ex: detergents, cosmetics, dander, poison ivy
Antigenic determinants
is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells
Major histocompatibility complex (MHC)
Two classes
Proteins that mark a cell as “self”
Class I MHC proteins
Class II MhC proteins
Class I MHC protein
Found in virtually all body cells
T cytotoxic cells Check the proteins if it is not a self protein it kills it
Class II MHC protein
Found on certain cells in the immune response
T Helper checks and macrophages kill the nonself cells
T cell maturation
In the thymus under negative and positive selection pressure
Positive selection
“Selects for” T cells capable of interacting MHC They become both immunocompetent and self tolerant
Others die by apoptosis are engulfed by macrophages this takes place in the thymic cortex
Apoptosis
Programmed cell death
Negative selection
After they pass positive selection the thymocytes enter the medulla. They are again presented with self antigen in complex with MHC molecules on antigen presenting cells. Thymocytes that interact to strongly with the antigen receive an apoptotic signal
Immunocompetence
B or T cells.
Display a unique type of receptor that respond to a distinct antigen
Become immunocompetent before they encounter antigens that may later attack
What determines which foreign substances are immune system will recognize and resist
Genes not antigens
A naïve cell
Antigen that may later attack
B cell maturation
Less understood, become immunocompetent and self tolerant in bone marrow
Anergy
Self reactive B cells are inactivated
Clonal deletion
Kills self reactive B cells
Receptor editing
B cells undergo a rearrangement of their antigen binding receptors
Antigen presenting cells APCs
Major role is to engulf foreign antigens and present fragments of these antigens on their own surfaces where they can be recognized by Tcells
How did B cells work
B cell -> clone -> plasma cell -> antibodies and memory cell
Plasma cells
Most clone cells become antibody secreting
Memory cells
Close that do not become plasma cells become these. immediate response to subsequent exposure of the same antigen
Antibodies
Bind to free antigens, Mark antigen for destruction by specific or nonspecific mechanisms
Do antibodies kill bacteria?
No
Naturally acquired active immunity
Response to a bacterial or viral infection
Artificially acquired active immunity
Response to a vaccine
Naturally acquired active immunity
From the mother to the fetus via the placenta
Artificially acquired passive immunity
From the injection of a serum such as a gamma globulin
Immunoglobulins
Constitute the gamma globulin portion of blood proteins, Are soluble proteins, Activated B cells and plasma cells in response to an antigen, capable of binding specifically w/ that antigen
IgG
Only one that can cross the placenta, main class of antibodies most abundant, Most diverse
IgA
Mostly in tears, milk, mucous, saliva. Prevent pathogens from attaching to epithelium
IgM
Large macromolecule, antibody of ABO blood types
IgE
Associated with basophil and mast cells, causes the cells release of histamine and other inflammatory chemicals. elevated in patients allergies or internal parasites
IgD
Found on B cell membrane, function as an antigen receptor of B cell found in many species, but not well understood
Variable reason vs constant region
Each chain has a variable (v) region at one end and a constant (c) region at the other
Somatic recombination
Gene segments are shuffled and combined in different ways by each B or T cell as it becomes immunocompetent; info of the newly assembled gene is expressed as B and T cell receptors as antibodies
Plan of attack
Defensive mechanisms used by antibodies Precipitation Lysis Agglutination Neutralization
Precipitation
Soluble molecules are cross-linked into large insoluble complexes (IgM IgG IGA) clumped antigen easier for phagocytes to engulf
Lysis
Activates (MAC) Membrane attack complex bores holes in bacterial membrane (IgM, IgG)
Agglutination
Antigen, antibodies reaction causes microbes to stick together IgM is strong, IgA is week
Neutralization
Antibodies bind to block specific sites on viruses or exotoxins thus preventing these antigens from binding to receptors on tissue cells
Monoclonal antibodies
Pure antibody preparation, specific for a single antigenic determinant, produced from descendants of a single cell
Hybridomas
All hybrids made from a fusion of a tumor cell to a B cell have desirable properties of both parent cells - indefinite proliferation as well as the ability to produce a single type of antibody
How do T cells work
Recognize self and nonself
Cytotoxic T cell
Destroy cells harboring foreign antigens attack cells infected by viruses
Helper T cell
Stimulate growth and differentiation of B and T cells they’re like generals and tell what to do
How do cytotoxic T cells and natural killer cells destroy their target cells
They both used perforin to bore holes into target cells
MALT vs GALT
MALT- Mucosal immune system- GI tract, respiratory tract, urogenital tract, mammary glands
GALT-gut associated lymphoid tissue peyers patch, appendix, tonsils and adenoids
What are privileged sites and why do we have them
The uterus, testees and anterior chamber of the eye.
are isolated from adaptive immune system
after puberty our bodies change protects reproductive so we can create life.
Prevents the eye from being attacked by the foreign matter that lands on the eye
What are compromised individuals
They have impaired resistance
Young- Immune system not developed
Elderly- cell mediator response in decline
Season- In June T cell at lowest level
PoOr nutrition- impairs antibody synthesis
Excessive exercise- Depressed immune system
Pregnancy- Cell mediated immunity decreases
Traumatic injury- Tissue repair competes for proteins
Autographs
Grafts transplanted from one site of the body to another in the same person
Isografts
Grafts between identical twins
Allografts
Transplants between individuals that are not identical twins but belong to same species
Xenografts
Grafts taken from another animal species
Immunodeficiencies
Congenital and acquired conditions in which function or production of an immune cells phagocytes or complement is abnormal
