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Antigen
Foreignness-must be foreign substance to elicit and immune response (non-self)
-High molecular weight
-*Chemical structural complexity- More complex, more immunogenic it will be
----Mostly proteins and some polysaccharides
Dosage, route and timing of exposure
Epitopes
Antigen determinants- regions of antigen that specifically bind
1st= Barriers
2nd= Inflammatory Response and Phagocytosis
With the non-specific/innate immune system, what is the 1st and 2nd line of defense?
1st line of defense
Barriers: skin, mucous membranes, and secretions (tears, saliva, sweat, gastric acid)
2nd line of defense
Inflammatory response and phagocytosis
A breach of the body's physical barriers stimulates the innate immune system.
Characteristics of the Innate Immune System
Present from birth
No memory
Dominant system of defense in most organisms
Nonspecific response (acute inflammation): Certain cells (Neutrophils, macrophages, Natural Killer cells, etc), Phagocytosis, complement system, and fever
Acute inflammation
This is a VASCULAR response characterized by edema, redness (erythema) and pain
Neutrophil (Polymorphonucleocyte or PMN)
First cells to respond BOARD ALERT
Most numerous WBC
Described as first line defenders (the immune response cannot proceed without the initiation of the inflammatory response by these)
These are phagocytes-capable of engulfing and absoring bacteria
Collagenase and elastase
Neutrophils or PMNs release powerful enzymes and cytokines. What are they?
Chemotactic factors (emigration)!
Neutrophils or PMNs migrate in response to?
Diapedesis
What allows PMNs to squeeze through endothelial cells to relocate into connective tissue?
Acute Inflammation
This migration by the neutrophils causes extravasation of a few red blood cells resulting in the hallmark erythema and edema associated with?
Periodontal disease
When something is wrong with neutrophil function, what results? BOARD ALERT
3 main functions of Macrophages
Phagocytosis, cytokine production, and is an antigen presenting cell
Phagocytes
Engulf and digest bacteria
Cytokines
Hormone-like messengers which allow for cell-to-cell communication
Macrophages! BOARD ALERT
What transports, processes and presents antigens to lymphocytes?
Natural Killer (NK) cells
Destroy tumor cells and virally infected cells
Non-specific killers that destroy their target's cell membranes while enhancing the inflammatory response-they are NOT phagocytes!!
Kill without antibody
Active without prior exposure to antigen!
Mast cells
Are common at sites in the body that are exposed to external environment and are found in close proximity to blood vessels
Degranulation-Release of cytoplasmic granules is stimulated by traumatic or microbial injury
The location of mast cells allows them to regulate vascular permeability and effector cell recruitment through?
Histamine
When mast cells release this and leukotrienes, capillaries dilate and vascular permeability is dramatically increased leading to edema. BOARD ALERT
Interferons
Secreted by host cell when a cell becomes infected with a virus
Stimulate healthy cells to produce proteins that interfere with the synthesis of viral proteins
Complement system (Complement cascade)
Is a group of 20+ proteins that circulate in the blood and serve to complement or assist other defensive mechanisms (Inflammation, phagocytosis, pathogen lysis)
Once this is activated, it goes through several steps until neutralization is achieved. If one component foes not function properly, the whole system fails
IgG and IgM
What are the two antibodies capable of activating the complement system?
Pyrogens
When macrophages detect and attack microbes, they release these chemicals into the bloodstream that cause the brain to reset the thermostat to a higher temperature
Less hospital to most pathogens
Increases the metabolic rate of body cells
What are the benefits of a fever?
Affect the shape and function of some bodily proteins
A fever of over 100 degrees that lasts longer than 2 days requires medical attention
What are the downsides of a fever?
Specific/adaptive Immune System
If the innate immune system is unsuccessful in destroying the pathogens, this sets in. It takes longer to start to work but is much more accurate.
It remembers antigens and reacts quicker on subsequent exposures
T cells
Derived from bone marrow-mature in the Thymus
Recognize infected cells and destroy and eliminate from the body
Stimulate B cells
B cells
Derived from bone marrow-mature in bone marrow
Receptor sites for antigens
Differentiate into plasma cells- producing antibodies
Stimulate T cells to allow immune response to grow
B cells and plasma cells
What cells are responsible for producing antibodies (immunoglobulins)? BOARD ALERT
IgE
What is the primary antibody involved in Type 1 hypersensitivity and causes release of histamine from mast cells and basophils?
Penicillins
What is the most likely antibiotic to produce anaphylactic shock?
Type II cytotoxic reaction
Antigen/antibody complex is fixed to circulating blood cell-resulting in lysis
EX: Rh and Transfusion reactions
IgG
What is the only immunoglobulin to cross the placental barrier? BOARD ALERT
Type III Immune complex reaction
The interaction of an antigen and antibody produces an immune complex that ordinarily activates complement allowing for phagocytosis. Tissue damage presents in autoimmune diseases
Type IV delayed hypersensitivity
T lymphocytes and macrophages are involved in this hypersensitivity reaction
The T cells release cytokines which activate phagocytosis leading to tissue inflammation and injury.
EX: Contact dermatitis cause by topical application of a drug
