Term
|
Definition
• Is called specific or acquired immunity
– The body’s ability to recognize and defend itself against distinct invaders and their products
– Is a “smart” system whose “memory’ allows it to respond rapidly to a second encounter with a pathogen |
|
|
Term
| Elements of Specific Immunity |
|
Definition
• Is acquired over time
• Immunologists are scientists who study the cells and chemicals involved in specific immunity
• Antigens trigger specific immune responses
• Various cells, tissues, and organs are part of specific immunity
– Includes B and T lymphocytes |
|
|
Term
|
Definition
• Molecules that trigger a specific immune response
• Include components of bacterial cell walls, capsules, pili, and flagella, as well as proteins of viruses, fungi, and protozoa
• Food and dust can also contain antigenic particles
• Enter the body by various methods:
– Through breaks in the skin and mucous membranes
– Direct injection, as with a bite or needle
– Through ingestion or inhalation |
|
|
Term
The Nature of Antigens
Lymphatic System |
|
Definition
• Screens the tissues of the body for foreign antigens
• Composed of lymphatic fluid, vessels and lymphatic cells |
|
|
Term
|
Definition
• Form a one-way system that conducts lymph from local tissues and returns it to the circulatory system
– Lymph is a liquid with similar composition to blood plasma that arises from fluid leaked from blood vessels into surrounding tissues |
|
|
Term
|
Definition
• House leukocytes that recognize and attack foreign antigens present in the lymph
• Concentrated in the cervical (neck), inguinal (groin), axillary (armpit), and abdominal regions
• Receives lymph from afferent lymphatic vessels and drains lymph into efferent lymphatic vessels |
|
|
Term
| Other Lymphoid Tissues and Organs |
|
Definition
• Spleen
– Similar in structure and function to the lymph nodes
– Filters bacteria, viruses, toxins, and other foreign matter from the blood
• Tonsils and mucosa-associated lymphoid tissue (MALT)
– Physically trap foreign particles and microbes that are ingested or inhaled
– MALT includes the appendix, lymphoid tissue of the respiratory tract, and Peyer’s patches in the wall of the small intestine |
|
|
Term
|
Definition
• Arise and mature in the bone marrow
• Found primarily in the Secondary lymphoid tissue: spleen, lymph nodes, bone marrow, and Peyer’s patches
• Small percentage of B cells circulate in the blood
• Major function is the differentiation into plasma cells which secrete antibody |
|
|
Term
|
Definition
• Also called immunoglobulins (Ig)
• Soluble, glycoprotein molecules that bind antigen
• Secreted by plasma cells, which are activated and differentiated B cells
• Considered part of the humoral immune response since bodily fluids such as lymph and blood were once called humors |
|
|
Term
|
Definition
• Antigen-binding sites are complementary to antigenic determinants (epitopes)
– Due to the close fit, can form strong, noncovalent interactions
– Hydrogen bonds, ionic attractions, and hydrophobic interactions are involved |
|
|
Term
|
Definition
• Neutralization (both viruses and toxins)
• Opsonization
• Agglutination
• Activation of complement |
|
|
Term
|
Definition
• A single type of antibody is not sufficient for the multiple types of invaders to the body
• The class involved in the immune response depends on the type of foreign antigen, the portal of entry, and the antibody function needed
• 5 different classes of antibodies |
|
|
Term
Five Classes of Immunoglobulins
B Cell Receptor (BCR) |
|
Definition
• Is an antibody that remains associated with the cytoplasmic membrane
• Each B lymphocyte has multiple copies of a single type of BCR (either IgM or IgD)
• Antigen binding site is identical to that of the secreted antibody for that particular cell
• The randomly generated antibody variable region determines the BCR specificity |
|
|
Term
|
Definition
| • Each BCR on an individual cell is complementary to only one antigenic determinant |
|
|
Term
|
Definition
• Produced in the red bone marrow and mature in the thymus
• Circulate in the lymph and blood and migrate to secondary lymphoid tissue: lymph nodes, spleen, and Peyer’s patches
• Part of the cell-mediated immune response because they act directly against various antigens
– Endogenous invaders
– Many of the body’s cells that harbor intracellular pathogens
– Abnormal body cells such as cancer cells that produce abnormal cell surface proteins |
|
|
Term
|
Definition
• 3 types:
– Cytotoxic T cells
– 2 types of helper T cells (TH1 & TH2) |
|
|
Term
| Cytotoxic T cells (TC Cells) |
|
Definition
• Distinguished by the CD8 cell-surface glycoprotein
• Directly kill certain cells
– Cells infected with viruses and other intracellular pathogens
– Abnormal cells, such as cancer cells |
|
|
Term
| Helper T Cells (TH Cells) |
|
Definition
• Distinguished by the CD4 cell-surface glycoprotein
• Function to “help” regulate the activities of B cells and cytotoxic T cells during an immune response
• Secrete various soluble protein messengers, called cytokines, that determine which immune response will be activated |
|
|
Term
| Helper T Cells (TH Cells) |
|
Definition
• 2 types
– Type 1 helper T cell (TH1):
• Assist development of cytotoxic T cells and macrophage activation.
– Type 2 helper T cell (TH2):
• Assist development of B cells and antibody formation |
|
|
Term
|
Definition
• Soluble regulatory proteins that act as intercellular signals when released from certain body cells
• Immune system cytokines signal among various leukocytes
• The complex web of signals among all the cell types of the immune system is referred to as the cytokine network |
|
|
Term
|
Definition
|
|
Term
|
Definition
| antiviral proteins that may act as cytokines |
|
|
Term
|
Definition
| proteins that stimulate stem cells to divide, maintaining a adequate supply of leukocytes |
|
|
Term
| Tumor necrosis factors (TNFs) |
|
Definition
| Secreted by macrophages and T cells to kill tumor cells and regulate immune responses and inflammation |
|
|
Term
|
Definition
| signal leukocytes to go to a site of inflammation or infection and stimulate other leukocytes |
|
|
Term
| Lymphocyte Editing by Clonal Deletion |
|
Definition
• Vital that immune responses not be directed against self (autoantigens)
• Body “edits” lymphocytes to eliminate any self-reactive cells |
|
|
Term
| Major Histocompatibility Complex (MHC) |
|
Definition
• Group of antigens first identified in graft patients
• Important in determining the compatibility of tissues in successful grafting
• Major histocompatibility class I antigens are glycoproteins found in the membranes of most nucleated cells of vertebrate animals
• Function to hold a peptide fragment from an intracellular protein (endogenous antigen) for presentation to T cells |
|
|
Term
| Major Histocompatibility Complex (MHC) |
|
Definition
• Antigens bind in the antigen-binding groove of MHC molecules
• 2 classes of MHC proteins
– MHC class I
– MHC class II |
|
|
Term
Number of Alleles in Caucasoids:
Antigen Processing |
|
Definition
• T-independent antigen
– Large antigen molecules with readily accessible, repeating antigenic determinants
– B cells can bind and respond to these directly without T cell cytokine help
• Stimulates B cells to differentiate into a plasma cell and produce antibodies |
|
|
Term
|
Definition
• T-dependent antigens
– Smaller antigens with less accessible antigenic determinants
– B cells require involvement from helper T cells to target these antigens
– Helper T cells are assisted by antigen presenting cells that process the antigen and make the antigenic determinants accessible to T cells
• Processing is different based on whether the antigen is exogenous or endogenous |
|
|
Term
| Processing of Exogenous Antigens |
|
Definition
• APC internalizes the invading pathogen and enzymatically digests it into smaller antigenic fragments which are contained within an endosome
• Endosome fuses with a vesicle containing MHCII molecules
• Each fragment binds to the antigen-binding groove of a complementary MHCII molecule
• The fused vesicle then inserts the MHCII-antigen complex into the cytoplasmic membrane so the antigen is presented on the outside of the cell |
|
|
Term
| Processing of Endogenous Antigens |
|
Definition
• Intracellular proteins are broken down into smaller peptide fragments by the proteosome; fragments transported into endoplasmic reticulum (ER)
• Each fragment binds to a MHCI molecule located in the ER
• The membrane is packaged into a vesicle by a Golgi body which is inserted into the cytoplasmic membrane so the antigen is displayed on the cell’s surface |
|
|
Term
Antigen Processing and Presentation
Humoral Immune Response |
|
Definition
• Body mounts humoral immune responses against exogenous pathogens
• Components of a humoral immune response
– B cell activation and clonal selection
– Antibody
– Memory B cells and the establishment of immunological memory |
|
|
Term
|
Definition
• Make up the majority of cells produced during B cell proliferation
• Each plasma cell secretes antibody molecules complementary to one specific antigenic determinant.
• The class of antibody produced is determined by signals from T-helper cells
• Are short-lived cells that produce massive amounts of antibody and then die within a few days |
|
|
Term
|
Definition
• Cells produced by B cell proliferation that do not secrete antibodies
• Cells that have BCRs complementary to the specific antigenic determinant that triggered their production
• Long-lived cells that divide only a few times and then persist in the lymphoid tissue
• Are available to initiate antibody production more rapidly if the same antigen is encountered again |
|
|
Term
| Cell-Mediated Immune Response |
|
Definition
• Responds to intracellular pathogens and abnormal body cells
• The most common intracellular pathogens are viruses but the response is also effective against intracellular bacteria
• Triggered when antigenic determinants of the pathogen are displayed on the host cell’s surface |
|
|
Term
|
Definition
• Specific immunity acquired during an individuals life
• 2 types |
|
|
Term
|
Definition
| immune response against antigens encountered in daily life |
|
|
Term
|
Definition
| response to antigens introduced via medical intervention |
|
|
Term
|
Definition
| products made by the individual (humoral or cell-mediated responses) |
|
|
Term
|
Definition
| passively receive antibodies made by another individual |
|
|
