Innate Immunity and Inflammation
Name the two types of immunity
Innate resistance and Adaptive (acquired) immune system
What are the end products of adaptive immunity?
Lymphocytes (T and B cells) and Antibodies: immunoglobulins (Ig)
What is the Fab?
antigen-binding fragment; acts as recognition sites (receptors) for antigenic determinants; binds antigen; has two identical fragments
spleen, lymph nodes, adenoids, tonsils, peyer patches (intestines) and appendix
Occurs during the initial exposure; during the latent period or lag phase, B cell differentiation occurs. After 5-7 days, an IgM antibody for a specific antigen is detected and an IgG response equal to or slightly less follows, thus the immune system is primed
Name the three human defense mechanisms
Second line: inflammation
Third line: adaptive immunity
Describe Clonal selection and cellular interaction of T-helper cells (Th) and APCs
Antigen is processed and presented to immune cells by antigen-presenting cells (APCs)
Results in differentiation of B cells into active antibody-producing cells (plasma cells) and differentiation of T cells into effector cells
Describe the Fc and the polypeptide chains
Fc= crystalline fragment, responsible for biologic function; activates complement and opsonization
Polypeptide chains: two light chains and two heavy chains are held together with disulfide bonds; heavy chains determines the type of antibody
What are NK cells and what do they do?
natural killer cells that are complement to Tc cell mechanisms; they are similar to T cells but do not undergo maturation in the thymus and they lack antigen-specific receptors.
They kill abnormal cells that do not express MHC class l. They perform antibody-dependent cell-mediated cytotoxicity and can attach to the IgG through Fc receptors and activate its normal killing mechanisms
Anamnestic; more rapid than primary response. Larger amounts of antibody are produced. Rapidity is due to the presence of memory cells that do not have to differentiate. IgM is produced in similar quantities to the primary response but IgG is produced in considerably greater numbers.
Describe the difference between mutualistic relationship and opportunistic members of normal microbiome
Mutualistic: living arrangement is beneficial to both organisms (do not usually cause disease, but instead protect us from worse microbes)
Opportunistic: usually provide benefit by fighting off other microbes, but given the opportunity, they can/will cause disease
Describe the difference between humoral and cell-mediated immunity
Humoral includes B cells and circulating anitbodies and causes direct inactivation of a microorganism or the activation of inflammatory mediators; it primarily protects against bacteria and viruses
Cell-mediated immunity differentiates T cells and primarily protects against viruses and cancer.
Work together to provide immunity and memory; respond more rapidly and efficiently on subsequent exposure to same antigen
What are CD1 Molecules, where are they found and what do they do?
Antigen-presenting molecules; found on APCs and thymus cells; and present lipid antigens (mycobacterium tuberculosis and mycobacterium leprae)
What do T-Helper Lymphocytes do and what are the steps?
2.Th cells undergo differentiation
3. Mature Th cells interact with plasma or T-effector cells
BCR can react with soluble antigens (signals originate from BCR complex and other surface co-receptors, antigen-bearing macromolecule is eventually presented on the cell surface and recognized by Th2 cell.
B cells can be activated via complement receptors (Ag activates complement system through alternate or lectin pathways
B cells can be activated directly by antigens (bypassing Th cells) stimulating maturation& differentiation= T-independent antigens
B cells can undergo class-switches based on needs of body; except if they are directly activated
Describe the vascular response
First the blood vessels dilate and immediately constrict thereafter. Then there is increased vascular permeability and leakage of fluid out of the vessel. Then there is WBC adherence to the inner walls of the vessels, and migration through the vessel walls to the site of injury (diapedesis)
Describe Active acquired immunity versus passive acquired immunity
Active: antibodies or T cells produced after either a natural exposure to an antigen or after immunization; long lived
Passive: preformed antibodies or T lymphocytes are transferred from a donor to a recipient; occurs naturally or artificially, temporary or short lived
Describe CD2, CD3, CD4 and CD8 surface markers
CD2 on the cell surface of all T cells
CD3 : TCR accessory molecules that are collectively called CD3 and are expressed
CD4 surface molecules that recognize antigens presented by MHC class ll molecules and develop into Th cells
CD8 surface markers: recognize antigens presented by MHC class l molecules and become mediators of cell-mediated immunity and directly kill other cells (T-cytotoxic Tc cells)
What do Tc lymphocytes do and describe the process
they destroy cancer cells or cells infected with a virus; they induce apoptosis.
Perforin penetrates polymerizes and forms pores in the target cell's plasma membrane. Granzymes enter target cell through the perforin-lined pores, and activate cellular enzymes (caspases) invovled in apoptosis. Direct receptor interactions activate Fas signals the target cell to undergo apoptosis
Describe Antibody function and both mechanisms
Protects against infection.
Direct: Neutralization (Ab inactivates/blocks binding of antigen to receptor on target cell, Agglutination (clumps insoluble particles in suspension), Precipitation (makes soluble antigen into insoluble precipitate)
Indirect: complement and phagocytes
What are the protein systems that provide a biochemical barrier against invading pathogens? What do they all contain?
Complement system, clotting system, and kinin system. Contain inactive enzymes (proenzymes). First proenzyme is converted to an active enzyme and the activation of the first component of a system results in a sequential activation of other components
Tell me all of the antibody (immunoglobulin) classes
IgG: must abundant class, transported across the placenta. Accounts for most of the protective activity against infections. Four classes:IgG1, IgG2, IgG3, IgG4
IgA: two subclasses, IgA1: predominantly in blood, IgA2: predominantly in normal body secretions. Body secretions are dimers anchored by the J-chain and "secretory" piece (may function to protect IgAs against enzyme degradation
IgM: largest of immunoglobulins (pentamer stabilized by J-chain. First antibody produced during primary response to an antigen (synthesized during fetal life)
IgE: least concentrated of the immunoglobulin classes in the circulation; acts as a mediator of many common allergic responses; defends against parasites (large worms)
IgD: information on IgD limited; located primarily on the surface of developing B lymphocytes, functions as. one type of B-cell antigen receptor
B-cell Maturation in DETAIL: where, what do they develop, produce, changes?
develops surface markers: CD45R and the IL-7 receptor (produced by stromal cells and is critical in driving the further differentiation and proliferation of the B cell)
Produce BCR's
Changes in characteristic surface markers: CD21 complement receptor and CD40 adhesion molecule required for later interactions with Th cells
central tolerance
Describe the process of B-cell Activation entirely
It results from the recognition of soluble antigen by BCR's, processing of antigen, and presentation by MHC class ll antigens to Th2 cells. When an immunocompetent B cell encounters an antigen for the 1st time, B cells with specific BCR's are stimulated to differentiate and proliferate--> becomes a plasma cell= a factory for antibody production (single class or subclass of antibody)
Describe Secretory (Mucosal) Immune response entirely
Lymphoid tissues protect external body surfaces with the goal of stopping viral and bacterial invasion before local or systemic disease develops AND prevent to a carrier state; Antibodies present in tears, sweat, saliva, mucus, and breast milk and act locally. IgA is the dominant immunoglobulin and works to prevent attachment and invasion of pathogens through mucosal membranes (small numbers of IgG and IgM are present)