Exam 1: Ch 50, 51, 52, 53 Flashcards
agglutination
clumping effect occurring when an antibody acts as a cross-link between two antigens.
antibody
Is a large protein, called an immunoglobulin, that consists of two subunits, each containing a light and a heavy peptide chain held together by a chemical link composed of disulfide bonds. Each subunit has one portion that serves as a binding site for a specific antigen and another portion that allows the antibody molecule to take part in the complement system.
antigen
substance that induces the production of antibodies
antigenic determinant
the specific area of an antigen that binds with an antibody combining site and determines the specificity of the antigen-antibody reaction
apoptosis
programmed cell death that results from the digestion of deoxyribonucleic acid by endonucleases.
B cells
Cells that are important for procuring a humoral immune response
Cellular immune response
the immune system’s third line of defense, involving the attack of pathogens by T cells
Complement
series of enzymatic proteins in the serum that, when activated, destroy bacteria and other cells
Cytokines
generic term for non-antibody proteins that act as intercellular mediators, as in the generation of immune response.
Cytotoxic T cells
lymphocytes that lyse cells infected with virus; also play a role in graft rejection.
Epitope
any component of an antigen molecule that functions as an antigenetic determinant by permitting the attachment of certain antibodies.
helper T cells
lymphocytes that attack foreign invaders (antigens) directly
Humoral immune response
the immune system’s second line of defense; often termed the antibody response
Immune response
the coordinated response of the components of the immune system to a foreign agent or organism
Immune system
the collection of organs, cells, tissues, and molecules that mediate the immune response.
Immunity
the body’s specific protective response to a foreign agent or organism; resistance to disease, specifically infectious diseases.
Immunopathology
study of diseases resulting in dysfunctions within the immune system.
Immunoregulation
complex system of checks and balances that regulates or controls immune responses
Interferons
proteins formed when cells are exposed to viral or foreign agents; capable of activating other components of the immune system
Lymphokines
substances released by sensitized lymphocytes when they come in contact with specific antigens
Memory Cells
cells that are responsible for recognizing antigens from previous exposure and mounting an immune response.
Natural killer (NK) cells
lymphocytes that defend against microorganisms and malignant cells.
Null lymphocytes
lymphocytes that destroy antigens already coated with the antibody.
Opsonization
The coating of antigen-antibody molecules with a sticky substance to facilitate phagocytosis.
Phagocytic cells
cells that engulf, ingest, and destroy foreign bodies or toxins
Phagocytic immune response
the immune system’s first line of defense, involving white blood cells that have the ability to ingest foreign particles
Stem cells
precursors of all blood cells; reside primarily in bone marrow
suppressor T cells
lymphocytes that decrease B-cell activity to a level at which the immune system is compatible with life
T cells
cells that are important for producing a cellular immune response.
Immune function is affected by a variety of factors such as:
central nervous system integrity general physical and emotional status medications dietary patterns stress of illness, trauma, or surgery
Immune memory is:
a property of the immune system that provides protection against harmful microbial agents despite the timing of re-exposure to the agent.
Disorders of the immune system may stem from:
- excesses or deficiencies of immunocompetent cells
- alterations in the function of these cells
- immunologic attack on self-antigens
- inappropriate or exaggerated responses to specific antigens
Autoimmunity
normal protective immune response paradoxically turns against or attacks the body, leading to tissue damage
Hypersensitivity
body produces inappropriate or exaggerated responses to specific antigens
Gammopathies
Immunoglobulins are overproduced
Primary immune deficiencies
deficiency results from improper development of immune cells or tissues; usually congenital or inherited
Secondary immune deficiencies
Deficiency results from some interference with an already developed immune system; usually acquired later in life
The major components of the immune system include:
central and peripheral organs, tissues, and cells: Adenoids/Tonsils Thymus Bronchus-associated lymphoid tissue Axillary lymph nodes Spleen Intestine Peyer's patches Appendix Inguinal lymph nodes Bone marrow (B cells and T cells)
Bone marrow
WBCs involved in immunity are produces in the bone marrow.
Lymphocytes are generated from stem cells.
2 types of lymphocytes: B cells and T cells
B cells: mature in the bone marrow then enter circulation
T cells: move from the bone marrow to the thymus, where they mature into several kinds of cells with different functions.
Lymphoid tissues
Lymph nodes, spleen, blood, and lymph
- Spleen: red/white pulp; acts as a filter. Red pulp is site where RBCs are destroyed. White pulp contains concentrations of lymphocytes.
- Lymph Nodes: remove foreign material from the lymph system before it enters the bloodstream. They also serve as centers for immune cell proliferation.
- Remaining lymphoid tissues contain immune cells that defend the body’s mucosal surfaces against microorganisms.
The basic function of the immune system is to:
remove foreign antigens such as viruses and bacteria to maintain homeostasis.
There are 2 general types of immunity:
- natural (innate) immunity-present at birth
2. acquired (adaptive) immunity-develops after birth
Natural immunity
- Is nonspecific
- provides broad spectrum of defense against and resistance to infection
- first line of host defense following antigen exposure, because it protects the host “without remembering” prior contact with an infectious agent.
- co-coordinates the initial response to pathogens through the production of cytokines and other effector molecules.
- cells involved include macrophages, monocytes, dendritic cells, NK cells, basophils, eosinophils, and granulocytes.
- the early events in this process are critical in determining the nature of the adaptive immune response.
Natural immune mechanisms can be divided into two stages:
Immediate: occurring within 4 hours
Delayed: occurring between 4 and 96 hours after exposure
White Blood Cell Action
-WBC’s or leukocytes, participate in both the natural and the acquired immune responses.
Granulocytes fight invasion by foreign bodies or toxins by releasing cell mediators, such as histamine, bradykinin, and prostaglandins, and engulfing the foreign bodies or toxins.
-Granulocytes include neutrophils, eosinophils, and basophils.
Neutrophils
are the 1st cells to arrive at the site where inflammation occurs.
Eosinophils and basophils increase in number during
allergic reactions and stress responses.
Monocytes function as
phagocytic cells, engulfing, ingesting, and destroying greater numbers and quantities of foreign bodies or toxins than granulocytes do.
60-70% of lymphocytes in the blood are
T cells
10 to 20% of lymphocytes in the blood are
B cells
The inflammatory response is a major function of the natural immune system that is elicited in response to
tissue injury or invading organisms.
Chemical mediators assist in the inflammatory response by:
minimizing blood loss walling off the invading organism activating phagocytes promoting formation of fibrous scar tissue regeneration of injured tissue
Physical surface barriers include:
intact skin
mucous membranes
cilia of the respiratory tract
Chemical barriers
mucus acidic gastric secretions enzymes in tears and saliva wax sweat
If an immune response fails to develop and clear an antigen sufficiently, the host is considered to be:
Immunocompromised or immunodeficient
If immune regulation is overtly robust or misdirected, the following may result:
allergies
asthma
autoimmune disease
Most microbial infections induce an inflammatory response mediated by:
T cells and cytokines, which, in excess, can cause tissue damage.
The acquired immune response is broadly divided into two mechanisms:
- the cell-mediated response, involving T-cell activation
2. effector mechanisms, involving B-cell maturation and production of antibodies.
Active acquired immunity
refers to immunologic defenses developed by the person’s own body. This immunity typically lasts many years or even a lifetime.
Passive acquired immunity
is temporary immunity transmitted from a source outside the body that has developed immunity through previous disease or immunization.
When the body is invaded or attacked by bacteria, viruses, or other pathogens, it has 3 means of defense?
- the phagocytic immune response
- the humoral or antibody immune response
- the cellular immune response
1st line of defense
The phagocytic immune response, primarily involves WBCs, which have the ability to ingest foreign particles and destroy the invading agent
2nd protective response
Humoral immune response (sometimes called the antibody response), begins with the B lymphocytes, which can transform themselves into plasma cells that manufacture antibodies. These antibodies are highly specific proteins that are transported in the bloodstream and attempt to disable invaders.
3rd mechanism of defense
The cellular immune response, also involved T-lymphocytes, which can turn into special cytotoxic (or killer) T cells that can attack the pathogens.
The structural part of the invading or attacking organism that is responsible for stimulating antibody production is called an:
antigen (or an immunogen)
There are four well-defined stages in an immune response:
recognition, proliferation, response, and effector.
Recognition stage of an immune response
- recognition of antigens as foreign, or non-self, by the immune system is the initiating event in any immune response.
- it involves the use of lymph nodes and lymphocytes for surveillance
Proliferation stage of an immune response
- the circulating lymphocytes containing the antigenic message return to the nearest lymph node
- once in the node, these sensitized lymphocytes stimulate some of the resident T and B lymphocytes to enlarge, divide, and proliferate.
- T lymphocytes differentiate into cytotoxic (or killer) T cells, whereas B lymphocytes produce and release antibodies.
Response stage of an immune response
- the differentiated lymphocytes function in either a humoral or a cellular capacity.
- this stage begins with the production of antibodies by the B lymphocytes in response to a specific antigen
- the cellular response stimulates the resident lymphocytes to become cells that attack microbes directly rather than through the action of antibodies. These transformed lymphocytes are known as cytotoxic (killer) T cells.
Viral antigens induce a _________ response.
Cellular.
-This response is manifested by the increasing number of T lymphocytes seen in the blood tests of people with viral illnesses such as infectious mononucleosis.
Effector stage of an immune response
- either the antibody of the humoral response of the cytotoxic (killer) T cell of the cellular response reaches and connects with the antigen on the surface of the foreign invader.
- This initiates activities involving interplay of antibodies, complement, and action by the cytotoxic T cells.
Humoral immune response
Is characterized by the production of antibodies by B lymphocytes in response to a specific antigen.
Antigen recognition
- B lymphocytes recognize and respond to invading antigens in more than one way.
- B lymphocytes respond to some antigens by directly triggering antibody formation; however, in response to other antigens, they need the assistance of T cells to trigger antibody formation
- with the help of macrophages, the T lymphocytes are believed to recognize the antigen of a foreign invader
- Memory cells are responsible for the more exaggerated and rapid immune response in a person who is repeatedly exposed to the same antigen.
Humoral Responses (B cells)
- bacterial phagocytosis and lysis
- anaphylaxis
- allergic hay fever and asthma
- immune complex disease
- bacterial and some viral infections
Cellular responses (T cells)
- transplant rejection
- delayed hypersensitivity (tuberculin reaction)
- graft-versus-host disease
- tumor surveillance or destruction
- intracellular infections
- viral, fungal, and parasitic infections
Role of antibodies
- Defend against foreign invaders in several ways, and the type of defense used depends on the structure and composition of both the antigen and the immunoglobulin.
- The antibody molecule has at least two combining sites, or Fab fragments.
- antibodies promote the release of vasoactive substances, such as histamine and slow-reacting substances, two of the chemical mediators of the inflammatory response.
- antibodies do not function in isolation; rather, they mobilize other components of the immune system to defend against the invader.
Immunoglobulins
- The body can produce 5 different kinds
- IgA, IgD, IgE, IgG, and IgM
- classification is based on the chemical structure and biologic role of the individual immunoglobulin
IgG
- 75% of total immunoglobulin
- appears in serum and tissues (interstitial fluid)
- assumes a major role in bloodborne and tissue infections
- activates the complement system
- enhances phagocytosis
- crosses the placenta
IgA
- 15% of total immunoglobulin
- appears in body fluids (blood, saliva, tears, breast milk, and pulmonary, gi, prostatic, and vaginal secretions)
- protects against respiratory, gi, and gu infections
- prevents absorption of antigens from food
- passes to neonate in breast milk for protection
IgM
- 10% of total immunoglobulin
- appears mostly in intravascular serum
- appears as the 1st immunoglobulin produced in response to bacterial and viral infections
- activates the complement system
IgD
- 0.2% of total immunoglobulin
- appears in small amounts in serum
- possibly influences B-lymphocyte differentiation, but role is unclear
IgE
- 0.004% of total immunoglobulin
- appears in serum
- takes part in allergic and some hypersensitivity reactions
- combats parasitic infections
The portion of the antigen involved in binding with the antibody is referred to as the:
antigenic determinant
The most efficient immunologic responses occur when the antibody an antigen fit like:
a lock and key.
Cross-reactivity
-Poor fit can occur with an antibody that was produced in response to a different antigen
-This phenomenon is known as cross-reactivity
Ex: strep and heart valve damage
Cellular Immune Response
- T lymphocytes are primarily responsible for cellular immunity
- stem cells continuously migrate from the none marrow to the thymus gland, where they develop into T cells
- despite partial degeneration of the thymus gland that occurs at puberty, T cells continue to develop here.
- T cells attack foreign invaders directly rather than by producing antibodies.
Types of T Lymphocytes
- T cells include effector T cells, suppressor T cells, and memory T cells.
- The two major categories of effector T cells are helper T cells and cytotoxic T cells; they participate in the destruction of foreign organisms
Helper T cells
- Are activated on recognition of antigens and stimulate the rest of the immune system.
- When activated, they secret cytokines, which attract and activate B cells, cytotoxic T cells, NK cells, macrophages, and other cells of the immune system.
- They also produce lymphokines, one category of cytokines
Cytotoxic T Cells
- Killer T cells
- attack the antigen directly by altering the cell membrane and causing cell lysis and by releasing cytolytic enzymes and cytokines.
- Lymphokines can recruit, activate, and regulate other lymphocytes and EBCs.
- these cells then assist in destroying the invading organism.
Suppressor T cells
-have the ability to decrease B-cell production, thereby keeping the immune response at a level that is compatible with health.
Memory cells
are responsible for recognizing antigens from previous exposure and mounting an immune response.
Null Lymphocytes
- along with NK cells, are other lymphocytes that assist in combating organisms.
- These cells are distinct from B cells and T cells and lack the usual characteristics of those cells.
- Null lymphocytes are a subpopulation of lymphocytes and destroy antigens already coated with antibody.
- antibody-dependent, cell-mediated cytotoxicity.
Complement
- circulating plasma proteins, known as complement, are made in the liver and activated when an antibody connects with its antigen.
- plays an important role in the defense against microbes.
Destruction of invading or attacking organisms or toxins is not achieved merely by the binding of the antibody and antigens….
It also requires activation of complement, the arrival of killer T cells, or the attraction of macrophages.
Complement has 3 major physiologic functions:
- defending the body against bacterial infection
- bridging natural and acquired immunity
- disposing of immune complexes and the byproducts associated with inflammation
The complement cascade
- the proteins that comprise complement interact sequentially with one another in a cascading effect
- the cascade is important to modifying the effector arm of the immune system
- activation of complement allows important events, such as removal of infectious agents and initiation of the inflammatory response, to take place.
The complement cascade may be activated by any of three pathways:
Classic: triggered after antibodies bind to microbes or other antigens and is part of the humoral type of adaptive immunity.
Lectin: is activated when a plasma protein binds to terminal mannose residue on the surface glycoproteins of microbes.
Alternative: triggered when complement proteins are activated on microbial surfaces; this pathway is part of natural immunity.
Interferons have
antiviral and antitumor properties
Interleukin-5 (IL-5)
Stimulates the growth and survival of eosinophils and basophils.
Stem cell factor and IL-3
Serve as stimuli for multiple hematopoietic cell lines
Assessment of the Immune System
- begins during the health history and physical examination
- areas to assess include nutritional status, infections and immunizations, allergies, disorders and disease states, surgeries, medications, blood transfusions.
Vitamin D deficiency has been associated with
- increased risk of common cancers
- autoimmune diseases
- infectious diseases
Autoimmune disorders
-are the 5th leading cause of death by disease in females of reproductive age.
Agammaglobulinemia
Disorder marked by an almost complete lack of immunoglobulins or antibodies
Angioneurotic edema
Condition marked by development of urticarial and an edematous area of skin, mucous membranes, or viscera.
Ataxia
Loss of muscle coordination
Ataxia-telangiectasia
Autosomal recessive disorder affecting T-and B-cell immunity primarily seen in children and resulting in a degenerative brain disease
Hypogammaglobulinemia
lack of one or more of the five immunoglobulins; caused by B-cell deficiency
Immunocompromised host
Person with a secondary immunodeficiency and associated immunosuppression
Panhypoglobulinemia
General lack of immunoglobulins in the blood
Severe combined immunodeficiency disease (SCID)
Disorder involving a complete absence of humoral and cellular immunity resulting from an x-linked or autosomal genetic abnormality
Telangiectasia
vascular lesions caused by dilated blood vessels
Thymic hypoplasia
T-cell deficiency that occurs when the thymus gland fails to develop normally during embryogenesis; also known as DiGeorge syndrome
Wiskott-Aldrich syndrome:
Immunodeficiency characterized by thrombocytopenia and the absence of T and B cells
Immunodeficiency disorders may be caused by :
-a defect in or a deficiency of phagocytic cells, B lymphocytes, T lymphocytes, or the complement system
Regardless of the underlying cause, the cardinal symptoms of immunodeficiency include:
- chronic or recurrent and severe infections
- infections caused by unusual organisms or by organisms that are normal body flora
- poor response to standard treatment for infections
- chronic diarrhea
Primary immunodeficiencies
- the majority are diagnosed in infancy, with a male-to-female ratio of 5 to 1.
- To date more than 120 immunodeficiencies of genetic origin have been identified.