Immunity Basics
Define Immunity.
The ability to destroy foreign antigens and prevent future cases of certain infectious diseases.
Describe some characteristics of Innate immunity and list the 3 aspects that are utilized in its function.
-Characteristics- Is nonspecific, Responses are always the same, Does not create memory, Does not become more efficient with repeated exposure.-
-3 Aspects- Barriers, Defensive Cells, and Chemical defenses.
*Keep in mind that all 3 aspects work together and there is some overlap*
Describe Adaptive Immunity.
Characteristics: Is very specific, may involve antibody production, does create memory, often becomes more efficient with repeated exposure.
Is carried out by lymphocytes (T cells, B cells) and macrophages
Two mechanisms: cell-mediated (cellular) immunity and antibody-mediated (humoral) immunity
What are antibodies?
Proteins produced in plasma in response to foreign antigens.
What happens at the body's first exposure to a foreign antigen?
It stimulates antibody production, but they are produced slowly and in small amounts. The person may develop symptoms of clinical disease.
_____ are chemical markers that identify cells. Human cells have their own that identify all the cells in an individual as "self", the HLA types.
Antigens
Name the different parts of the epidermis that act as barriers through Innate immunity.
Stratum Corneum- nonliving, when unbroken is an excellent barrier to pathogens of all kinds.
Microbiota of the skin surface and fatty acids in sebum- limit growth of some bacteria on the skin.
Living cells of the epidermis produce defensins which are antimicrobial chemicals.
This mechanism of immunity does not result in the production of antibodies, but is effective against intracellular pathogens, fungi, malignant cells, and grafts of foreign tissue. Also uses these cells:
Helper T cells and macrophages – recognize antigens
Memory T cells – remember antigen, become active if enters body again
Cytotoxic (killer) T cells – chemically destroy antigens
Cell-Mediated (Cellular) Immunity
See figure 14-7 pg 332
True or False? An antibody can bond with many different types of antigens.
False, Each Antibody is specific to only one antigen.
What happens on the body's second exposure to a foreign antigen?
Memory cells initiate rapid production of large amounts of antibodies- possibly preventing a second case of the disease.
Foreign or "non-self" antigens can be recognized as such and destroyed by stimulating what? Name some examples of foreign antigens.
Antibody production and/or other immune responses/mechanisms
Bacteria, Viruses, Fungi, Protozoa, some Malignant cells
Aside from the epidermis, name at least 2 more examples of barriers considered Innate Immunity
-Subcutaneous Tissues with WBCs, Mucous membranes and areolar CT with WBCs, Ciliated upper respiratory epithelium, Hydrochloric acid of the gastric juices, Lysozyme in saliva and tears
This mechanism of immunity does involve antibody production; is effective against pathogens and foreign cells. These cells used and functions are as follows:
Helper T cells, macrophages, B cells – recognize
Memory B cells – remember antigens and initiate rapid response on second exposure
B cells become plasma cells – produce antibodies for antigen
The antibodies produced bond to an antigen, forming antigen-antibody complex which results in opsonization (meaning the antigen is now labeled "food")
Complement fixation – circulating complement proteins are activated
Antibody-Mediated (Humoral) Immunity
See figure 14-7 on page 332
What is Opsonization?
The labeling of an antigen as "food" for phagocytosis by macrophages or neutrophils.
Define Agglutination.
It means "clumping" This is what happens when antibodies bind to bacterial cells. The bacteria that are clumped together by attached antibodies are more easily phagocytized by macrophages.
What is Herd Immunity, Genetic Immunity, and Acquired Immunity?
Herd-The protection provided for nonimmune persons in a population by the presence of an immune majority.
Genetic- does not involve antibodies, is programmed into DNA
Acquired- Does involve antibodies, can be passive or active. In Passive, antibodies are acquired from another source- Naturally from mother to fetus or thru breast milk, or artificially through injection of antibody after presumed exposure. Active: is the production of one's own antibodies. Naturally- from a recovery from a disease or artificially through a vaccine.
These are defensive cells. How does each group function?
Phagocytes(macrophages, neutrophils)
Langerhans cells and other dendritic cells
Natural killer cells
Basophils and mast cells
Phagocytes – ingest and destroy pathogens
Langerhans- – takes ingested cells to lymph nodes
Natural Killer cells– chemical rupture of cell membranes of invading pathogens
Basophils/Mast cells– produce histamine and leukotrienes.
This cell strongly initiates one or both of the immune mechanisms: cell-mediated immunity and antibody mediated immunity.
Helper T cell
Name the 5 classes of antibodies
IgG, IgA, IgM, IgD, IgE
How does an antibody neutralize a virus?
By bonding to them and preventing their entry into cells.
Immunity has 2 main components. Name them.
Innate immunity and Adaptive Immunity
These are the body's Chemical Defenses. Define and explain the function of each.
Interferons (alpha-,beta-, and gamma-)
Complement
Inflammation
Interferon –are proteins produced by cells infected with viruses and by T cells. It cannot prevent virus entry into cells but does block their reproduction.
Complement proteins – group of 20 plasma proteins. Circulate in the blood until activated. Involved in the lysis of cellular antigens. May stimulate histamine release in inflammation or attract WBC to the site.
Inflammation: the body’s response to damage, vasodilation and increased capillary permeability – tissue fluid and WBCs increase at site. (Purpose: contain damage, eliminate cause, repairs. Signs: redness, heat, swelling, pain )
In this process of Antibody Mediated Immunity, the complement proteins bind to the antigen-antibody complex and lyse cellular antigens or enhance the phagocytosis of noncellular antigens.
Complement fixation
Give the location of each of the 5 classes of antibodies.
(*Review these and see their functions on table 14-1 pg 334)
IgG- Blood and extracellular fluid
IgA- External and internal secretions (tears, saliva, etc)
IgM- Blood
IgD- B lymphocytes
IgE- Mast cells or basophils
How does an antibody neutralize bacterial toxins?
By bonding to them and changing their shape.