Immunology Flashcards
Sequence of related host defense events beginning when a host encounters a substance as being “foreign” or “non-self” and leading to cellular and chemical defensive actions
Immune Response
What are the 8 various blood cells?
Stem cell Erythrocyte Neutrophil Eosinophil Basophil Monocyte Lymphocyte Macrophage
What are the general functions of lymph nodes and the spleen?
Site of some immune response activities
State the major characteristics of antigens, including the chemical nature and the typical minimal size.
Stimulates an immune response and reacts with antibodies or T-cell receptors.
Chemical Nature: Protein with complex 3-D configuration
Size: Relatively large molecule
The specific part of the immunogen (antigen) that specifies or determines the exact antibody to be produced.
Epitope
Antigen- specific proteins which bind to specific sites on antigens and assist in inactivating the antigen by attaching to it.
Antibody
What is the role of the Fab site? How man Fab is/are there on one immunoglobulin molecule?
Antigen specific binding site (lock and key for specific antigens).
2 Fab sites on outer branches
What are the major characteristics of innate responses?
Innate: non specific, general recognition and response to “foreign” substance.
- Route of transmission or portal or entry and type of microbe determine the nature of innate response.
What are the major characteristics of adaptive responses?
Adaptive: Specific response to “foreign” substance.
- Pre committed cells and tissues respond against the ‘foreign’ substance.
What are the differences between innate and adaptive responses?
Innate:
- Non-specific, general recognition and response.
- Rote, portal, or entry and type of microbe determine the nature.
Adaptive:
- Specific response
- Pre committed cells and tissues respond
Describe the Major Histocompatibility Complex (MHC) protein classes, where each is found, and what are their roles?
Class I: (one amino acid chain) found on virtually every cell in body.
Class II: (two amino acid chains) found only on immunocompetent cells, particularly B-cells and macrophages.
What significant surface molecule are on T-cells and what are their roles?
CD3: Mark mature T-cells
CD28: get the activation co-signal from CD80/86 on APC
CD40 receptor: bonds with B-cell on CD40
LFA-1: adhesion molecule on T-cell
What significant surface molecule are on B-cells and what are their roles?
CD40: Bonds with T-cells (CD40 receptor)
CD19,20, and 21: Used for identification
CD80/86: When B-cell acts as APC (binds with T-cells)
Where do the T-cells mature and where do they concentrate after they mature?
They mature in the thymus and concentrate in the lymph nodes
Where do the B-cells mature and where do they concentrate after they mature?
They mature in the bone marrow and concentrate in the peripheral lymphoid tissue
Bind antigens to specific receptors on the APC surface then place some digested antigen on their MHC-II molecule “present” it to the helper T-cells
Antigen-Presenting Cell
State the different types of Antigen-Presenting Cells and where they are found, significant surface components, and the major roles/ activities of APCs.
Macrophages: Capture antigenic material (whole microbes) via phagocytes
-Found: on Ag on MHC-11
B- Lymphocytes: capture “digested” antigenic material via antigen- specific B-Cell receptors (B-cells are not phagocytic)
-Found: On Ag on MHC-II
Dendritic Cells: little to no phagocytic capacity but process numerous MHC-II (good at capturing and presenting antigens)
- Found: Specific tissues initially then migrate
- Role: initiating antigen- specific T-cell responses
What are the primary cells involved in cell-mediated immunity response?
APC
T-lymphocytes (helper and cytotoxic)
Natural Killer
What are the primary cells involved in humoral immunity?
APC
Activated Helper T-lymphocyte
B-lymphocyte
Describe the key composite and activities of helper T-cells.
- Possess CD4 in addition CD3 and surface proteins
- Recognize antigen bound to MHC-II of APC
Describe the key composition and activities of cytotoxic T-cells.
- Posses CD8 and LFA-1
- Requires IL-2 from activated Helper-T for initial CD8 a activation and proliferation
- Destroy target cells by releasing granules containing toxic substances
A proteoglycan which serves to assemble a complex containing granzymes and perforin
Serglycin
A membrane- penetrating protein which creates an entrance into the target cell
Perforin
Cytotoxic protease molecules which cleave various proteins in the target cell’s cytoplasm thus leading to apoptotic death of the target cell
Granzymes
How are cytotoxic T-cells activated?
- Requires contact between antigen on MHC-1 and TCR
- Requires contact between LFA-1 and ICAM-1 (Intercellular Adhesion Molecule)
- “immunological synapse” between two cells (CTL and Target cell)
Remembers the antigen to which it is COMMITTED to respond QUICKLY
Memory Cells
What is the overall role of the cell-mediated immunity system?
Provide antigen-specific protection against intracellular viruses, intracellular bacteria, parasites, fungi, tumors, and transplanted organs through killing function of activated T-cell and NK
In the humoral response, ________-lymphocytes are activated to differentiate into_______ and produce.
B-lymphocytes
Plasma
The attachment of immunoglobulin molecules to the surface of an antigen (bacteria cell), MARKING the cell for rapid phagocytosis and increasing phagocyte adherence to cell.
Opsonization
IgM
Size: Largest, confined to blood vessels, 10 binding sites
Timing: 5 to 10 days for initial, 30 days production ends
Lifespan: short, 1/2=5 days
Relative concentration: moderate (120mg/dL)
Functions: Provides protection during primary response
Opsonizing effect
Blood stream defense
Activated complement
Which Is can cross the placenta?
IgG
Which Ig activate complement?
IgM and IgG
Which Ig have a potential opsonizing effect?
IgM and IgG
Which Ig provides most of the defense for mucosal areas?
IgA
Which Ig is elected by the parasitic infections?
IgE
Which Ig is produced in the greatest concentration?
IgG
Which Ig is increased during some allergic reactions?
IgE
Which Ig is produced first in sequence from plasma cells?
IgM
Which Ig provides major protection during primary response?
IgM
Which Ig provides major protection during secondary response?
IgG
Describe the function of IgE on mast cells in allergic reactions?
The cell releases histamines and other chemical mediators
What is the overall role of the humoral system?
- Neutralization of toxins
- Immunity to bacteria and some viruses by means of opsonizating immunoglobulins
The events which occur in the host’s immune system following FIRST TIME EXPOSURE to a specific foreign substance.
Primary response
RAPID and highly SPECIFIC response by the host’s immune system against a specific foreign substance which had been PREVIOUSLY ENCOUNTERED.
Secondary response
Primary response memory cells.
Absent
Secondary response time for Ig production.
Short
Primary response time for Ig production.
Lengthy
Primary response major Ig produced.
IgM
Secondary response major Ig produced.
IgG
Secondary response memory cells.
Present
What is Active Immunity?
- Results from direct stimulation of host immune system
- Duration of effects: long-lasting (due to production of memory cells)
- Primed to give secondary response (memory cells produced)
What is Passive Immunity?
- Results from transfer of pre-formed immunoglobulins and/or cells from a donor to the host (host immunize system does not participate)
- Duration of effects: transient, short-lived
- Not primed to give secondary response (no memory cells produced)
IgM relative size and Fab site
Largest, confined to blood vessels, pentamer of 5 basic molecules- 10 binding sites
IgG relative size
Smallest; passes through capillary walls and placenta
IgA relative size and Fab site
Medium; dimmer (two molecules joined) (secretory component facilitates entrance into secretory tissues)
IgE relative size and Fab site
Medium; monomer
IgD relative size
Small; monomer
Timing of production: IgM
- First immunoglobulins to appear in repose to initial exposure to antigen (5-10days)
- Production ends in about 30 days
Timing of production: IgG
- Begins several days after stimulation (10 days) -primary
- Begins very soon after stimulation (1-3 days) -secondary
- Says high for weeks or months
Timing of production: IgA
-Soon after stimulation (no difference in primary and secondary)
Lifespan: IgE
Shortest; T1/2= 1.5 to 2 days
Lifespan: IgA
Short; T1/2= 6 days
Lifespan: IgG
Longest; T1/2= 23 days
Lifespan: IgM
Short; T1/2= 5 days
Relative Concentration: IgE
Lowest of all Igs
Relative Concentration: IgA
Moderate
Relative Concentration: IgG
Highest
Relative Concentration: IgM
Moderate
Functions: IgM
- Primary Response
- Opsonizing effect (enhances of target cells by phagocytes)
- Activates complement
Functions: IgG
- Provides major protection during secondary response
- Highly specific
- Protection against circulating bacteria and viruses
- Small enough to pass through placenta (protection of newborn)
- Activates complement
- Opsonizing effect
Functions: IgA
- Defense through human secretions
- NOT activate complement
Functions: IgD
Surface receptor on B-cell (helps initiate immune response)
Functions: IgE
- Allergic reactions
- Increased production in parasitic infections
- Does not activate complement