DSA Intro to Immune System Flashcards
What are antigens?
are non-self substances (cells, proteins, lipids, DNA, polysaccharides) that are recognized by receptors on immune cells, thereby eliciting the immune response.
The _____ located on the membrane of immune cells interact with small portions of those antigens, designated as antigenic determinants or _____.
- Receptors
- Epitopes
What are epitopes
small portions of those antigens, designated as antigenic determinants
ANTIBODIES (also known as abs) are protiens that _____________________________________.
- abs
- appear in circulation after infection or immunization
Antibodies are _____ and are ___________. They are generically designated as ________.
- soluble
- present in irtually all body fluids
- immunoglobulins
Humoral Immunity
immune responses mediated by soluble effector molecules
The response to the first exposure to antigen is called the ________. Subsequent encounters with the same antigen lead to responses called _________. This usually are more ___________________ than primary responses.
- primary immune response
- secondary immune responses
- rapid, larger, and better able to eliminate the antigen
Secondary responses are the result of activation of _________. Define the latter.
- Memory cells
- long lived cells that were induced during the primary immune response
What does immunology memory do?
optimizes the ability of the immune system to combat persistent and recurrent infections, because each exposure to a microbe generates more memory cells and activates previously generated memory cells. Immunologic memory is one mechanism by which vaccines confer longlasting protection against infections.
Natrual immunity
- develops when a person is exposed to a live pathogen,
- develops the infection
- recovers from the disease, and becomes immune to this pathogen as a result of the immune response resulted from the primary infection.
- It takes several weeks to develop natural immunity, but it provides a long lasting protection.
Artificial immunity
- can be achieved by an artificial exposure to killed or attenuated pathogenic microorganisms without contracting an infection.
- Artificial immunity provides a long lasting protection. It takes several weeks and sometimes several doses of a vaccine to develop an artificial immunity.
- Artificial immunity is used only for prophylactics of infectious diseases. It cannot be used for therapeutic purposes, i.e. treatment of the ongoing infections.
Passive immunity
- Passive immunity occurs when the patient is given someone else’s Abs (usually from individuals who had recently survived an infection caused by the same pathogens) as a therapeutic treatment of the ongoing infection.
- When these Abs are introduced into the person’s body, the “loaned”
- Abs help prevent or fight certain infectious diseases. The protection offered by passive immunization is short-lived, usually lasting only a few weeks or months, but it helps protect right away.
Innate immune response provides the ___________________. Most of microorganisms that enter the body on the daily basis _________. are eliminated within minutes or hours by defense mechanisms mediated by innate immunity. An innate immune response consists of both ____ and _____ compoents.
- the first line of defense against infectious disease.
- An innate immune response consists of both cellular and humoral components.
Define cell mediated innate immune response:
include multiple cell types that use a set of specific receptors to recognize and remove pathogens and cellular debris.
Define humoral innate immune response
consists of complement, acute-phase proteins, and natural Abs which are generated against Ags derived from normal gastrointestinal microflora rather than being produced in response to an infection
What are the three properties of innate immunity
- present from birth and consist of nonspecific components available before the onset of infection
- Innate immune recognition uses preformed effector molecules to recognize broad structural motifs that are highly conserved within microbial species.
- Activation of innate immune responses results in an ACUTE INFLAMMATION ensuring that invading pathogens remain in check while the specific immune response is either generated or upregulated.
What are neutrophils, monocytes and macrophages? And what branch of immunity are they in?
- Cell mediated innate immunity
- they are phagocytes
Neutrophils, monocytes, and macrophages
are PHAGOCYTES. They can kill a wide variety of microorganisms and malignant cells. Killing can occur intracellularly after phagocytosis of bacteria or extracellularly by secretion of factors from the phagocytes that are harmful to the foreign cell.
Mast cells, basophils, and eosinophils are in what branch of immunity?
- cell mediated innate immunity
- they are essential components of host defenses against multicellular parasites but also play a pathogenic role in allergy.
NK cells play a key role in what?
- are used in cell mediated innate immunity
- play a key role in the elimination of infected and malignant cells. NK cells can identify virus-infected and malignant cells and cause their destruction by apoptotic mechanisms.
Humoral innate immunity
What are infammatory mediators and what branch of the immune response are they used in?
soluble molecules that are involved in innate immune responses.
Acute phase protiens
- proteins that rise in concentration that increases during an infection.
- one example is C-reactive protein
C reactive protien
- CRP
- The term CRP comes from its ability to bind to the C protein of pneumococci.
- OPSONIZATION with CRP promotes the uptake of pneumococci by phagocytes.
-Molecules such as antibodies and CRP that promote phagocytosis are said to act as ________.
Opsonins
Complement System
The complement system is a group of about 20 serum proteins whose overall function is the control of inflammation by several mechanisms
- Components of the complement system can lyse many bacterial species
- Complement fragments released in this reaction attract phagocytes to the site of the reaction.
- Complement components opsonize the bacteria for phagocytosis.
Activation of immune cells includes transcriptional activation, synthesis, and secretion of ______ and _____ .
cytokines and chemokines
Cytokines
represent a large group of soluble molecules involved in signaling between cells.
chemokines
are a large group of chemotactic cytokines that direct the movement of immune cells around the body, from the blood circulation into the tissues and to the appropriate location within each tissue.
ADAPTIVE IMMUNE SYSTEM
The adaptive (also called acquired) immune response accounts for highly-specific recognition of foreign antigens by receptors on the surface of B and T lymphocytes.
B cell receptor
- is the surface immunoglobulin that bind specific antigens.
- There are thousands of identical copies of BCR present on the surface of a single cell.
- B-cell activation occurs upon interaction of the BCR with antigen, leading to cell activation and differentiation into plasma cells, which secrete soluble immunoglobulins, or antibodies.
- B cells and antibodies together make up the HUMORAL IMMUNE RESPONSE of adaptive immunity
T cell receptors
- TCR also recognizes specific antigenic determinants (epitopes).
- T cells control the CELL-MEDIATE IMMUNE RESPONSE.
- Unlike the Ab, the TCR is present only on the surface of T cells but not a secreted form. On a single T cell, all TCRs are identical.
The process of T-cell activation requires a third group of cells called ______________.
Antigen Presenting Cells
What do APCs contain?
Major hisotcomaptabiity complexes.
_____ form a regulated pathway to present foreign antigens to T cells for subsequent recognition and triggering of specific responses to protect against disease.
Together the MHC and APC cells
Which cells are professional APC?
Macrophages, macrophage-related cells called dendritic cells, and B cells are the professional APCs.
Describe the activation of T cells.
- deliver activating ACCESSORY SIGNALS to T cells engaged in antigen recognition, both in the form of soluble mediators called cytokines and in the form of signals delivered by cell-cell contact via engagement of co-stimulatory molecules.
- During an infection, a small number of B cells and T cells bind to the antigen with high affinity and then undergo activation, proliferation, and differentiation.
- As a result, single B cell or T cell generates many identical clones of the original antigen activated cell. This process is called CLONAL SELECTION or CLONAL EXPANSION.
Autoimmunity
stimulate a response and the body’s own structures are attacked as if they were foreign
Hypersensitivity
Sometimes the result of specific memory is that re-exposure to the same stimulus, as well as or instead of eliminating the stimulus, has unpleasant or damaging effects on the body’s own tissues
Immunosuppression
Autoimmunity, hypersensitivity and, above all, transplant rejection sometimes necessitate the suppression of adaptive immune responses by drugs or other means. Transplanted cells or organs from another individual usually survive innate resistance mechanisms but are attacked by the adaptive immune response, leading to rejection
