What structures make up the innate immunity?
Structural and chemical barriers
Where do innate cells arise from?
Myeloid Progeintor cells
What feature of pathogens does the innate immunity system recognize?
Innate cells recognize general features of some pathogens. Usually composed of repeating subunits, peptidoglycans and LPS that are common to many organisms.
What is a PAMP?
PAMP's are Pathogen Associated Molecular Patterns.
What are PAMP's recognized by?
PAMP's are recognized by pattern recognition receptors (PRR's) that are found on a variety of immune cells.
Do innate cells communicate with the acquired immune response?
Yes Lymphokines and antibodies modulate the response of innate cells.
How do innate cells initiate acquired immunity?
Innate cells (macrophages, dendritic cells, ext.) help to initiate acquired immunity by processing and presenting antigens to lymphocytes.
Do innate cells release cytokines?
Innate cells produce cytokines that modulate acquired immune responses.
What immune response acts first, innate or acquired?
innate immune responses control infection until acquired immune responses have developed.
What type of cells mediate acquired immune responses?
Lymphocytes are the cells that mediate the acquired immune responses.
What unique feature of the acquired immunity allows for rapid mobilization of immune responses?
What purpose do lymphokines serve?
Lymphokines supply help to other lymphocytes and they also help to regulate the activities of innate cells (macrophages, NK cells, neurophils)
When lymphocytes encounter an epitope what protein factors are produced?
Lymphokines and Cytokines
What type of cell are all elements of the blood derived from and were would you find this cell?
Pluripotent hematopoietic stem cell (found in the bone marrow) gives rise to two progenitors that in turn give rise to the cells of the immune system
What cells does the myeloid progenitor cell serve as a precursor for? (4)
Granulocytes Macrophages Dendritic Cells Mast Cells
Granulocyte, what is this?
A granulocyte, or polymorphonuclear cell PMN, are groups of cells that are structurally and functionally distinguishable and make up the adaptive immune system
What are the three types of granulocytes?
neutrophils, eosinophils, and basophils
What does a neutrophil do?
A neutrophil is a phagocytic cell that helps activate the bactericidal mechanisms
What does an eosinophils do?
Eosinophils are cells that kill antibody-coated parasites.
What are macrophages?
macrophages, are scavenger cells that have receptors for a variety of structures that are common to infectous agents. *They play an important role in initiation of acquired immune responses.
Where does a macrophage come from?
What type of cell is the most potent stimulator of T cell responses?
What do dendritic cells actually do?
Dendritic cells take up antigens at the site of infection
What do mast cells do?
Mast cells degranulate to release histamine and other active agents that are involved in Type 1 Hypersensitivity reactions.
What cells present antigens to T-Cells?
Macrophages and dendritic cells take up antigens, process the antigen, and present the antigen to niave T-cells to initiate the development of acquired immunity.
What type of receptors do mast cells have on their surface?
Mast Cells have IgE receptors on their surface and their activity is modulated by the acquired immune response.
What are T-Cells and B-Cells derived from?
T cells and B cells are derived from common lymphoid progenitor cells
What is the primary component of the adaptive (acquired) immune system
How do lymphocytes recognize foreign antigens?
Lymphocytes express receptor molecules on their surface that allow them to specifically recognize foreign antigens.
What immune response do Natural Killer cells belong to?
Innate- they do not express antigen-specific cell surface receptors and thus, can not recognize specific antigens.
Where do cells of the immune system circulate?
The lymph system, where they patrol for invaders.
Do both B and T cells mature in the bone marrow?
NO, While both origionate in the bone marrow Only B cells (Bone-marrow derived cells) mature there.
Where do T cells mature?
In the Thymus T Cells = (Thymus derived cells)
What takes place in the peripheral lymphoid tissues?
This is where the adaptive immune response is initiated.
What are the central lymph organs?
Thymus and Bone Marrow
What are the peripheral lymph organs?
Spleen, Lymph nodes, Gut associated lymph tissue (GALT), Bronchial associated lymph tissue (BALT)
What components make up the GALT. And what purpose do they serve?
Tonsils adenoids appendix and Peters patches **They capture antigen from the epithelial surfaces of the gastrointestinal tract.
What are Peyer's Patches?
Peyer's patches are the most important and most highly organized of the GALT tissues. They contain M CELLS that collect antigens along the intestinal mucosa.
Describe the structure of a Peyer's Patch
Peyer's patches have a lymphocyte follicle that consists of a large central dome of B cells surrounded by T cells
Initial immunity to potential pathogens is mediated by __________ ?
Innate immune system
How do phagocytes initiate inflammatory responses?
By producing inflammatory responses ( Cytokines )
What is the purpose of an inflammatory response?
Inflammatory response facilitates uptake of antigen by phagocytes and increase the flow of lymph toward the draining lymphoid tissue. This facilitates antigen transport to secondary lymphoid organs.
What cells secrete antigen specific antibodies.
What serves as the B Cell Receptor?
Surface expressed antibody molecules.
What happens when a B Cell is activated?
Upon activation B Cells produce large quantities of antigen - specific antibodies that can bind to specific antibodies
What is the difference between T Lymphocytes and B Lymphocytes
T Lymphocytes do not secrete their surface receptor molecules upon activation
How are B Cells activated?
Once the B cell receptor binds to its cognate antigen (1st step) the B cell endocytoses the antigen, breaks it into pieces, and presents the antigen to an antigen-specific T helper cell. The helper T cell provides the cytokine signal (2nd step) to the B-Cell which causes proliferation and differentiation to make antibodies.
How are T Cells activated?
T Cells specifically recognize peptide fragments of antigens that are presented to the T cell by an antigen presenting cell (macrophage, dendritic cell, or B cell) 1. Binding of cognate peptide antigen 2. Co-stimulation signal by the antigen presenting cell
What are the antigen presenting cells?
Macrophages, dendritic cells, B Cells
How are antigens presented?
Each antigen presenting cell is able to take up antigen, process it into peptide fragments ( antigen processing) and then present the antigen on their cell surface to T-Cells
Peptide antigens, present on the surface of antigen presenting cells are a bound complex with two types of molecules, what are they?
MHC complex 1 and 2. MHC complex one and two bind very tightly to many different peptides in a non-specific way. **T Cell receptor can only bind to peptides that are presented on MHC molecules.
What do neutralization Ab's do?
Neutralize some pathogen - derived toxins and even some pathogens
What do opsonization Ab's do?
Some Ab's can coat antigens (or pathogens) which facilitates uptake of the antigen by phagocytes or NK cells.
What is complement activation?
some antibodies can coat antigens (or pathogens) serve as a receptor for the 1st component of the classic complement system. Such antibodies are said to "Fix complement" which facilitates destruction of the antigen or pathogen
What type of cells do antibodies activate?
Natural Killer Cells and Mast Cells.
Antibodies play an important role in the activation of natural killer cells for ___________ ?
Antibody- Dependent Cell- mediated Cytotoxicity
What two types of T cells are there?
Ones that express CD8+ on their cell surface and ones that express CD4 on their cell surface.
Which type of T cells recognize peptide antigens presented on MHC class I molecules ?
CD8+ T Cells recognize MHC Class I
Describe how T Cells are converted to Armed Effector CD8+ T Cells
Once Niave CD8+ T Cell has been activated through recognition of cognate peptide MHC class I complex and costimulation by an antigen presenting cell, the CD8+ T cell will proliferate and differentiate into armed effector CD8+ T cells.
What do Armed Effector CD8+ T cells do?
Armed CD8+ T cells are programmed for only ONE purpose: To kill cells that have the cognate peptide:MHC Class I complex on their surface: These cells are also called cytotoxic T lymphocytes or "Killa T Cells"
What do CD4+ T cells differentiate into?
T helper 1 CD4+ or Th1 CD4+ cells
What do T helper CD4+ or Th1 CD4+ cells do?
The primary role of these cells is supply cytokine signals to macrophages; these cells up regulate various activities of the macrophage which increase its ability to kill ingested bacteria to more efficiently present peptide antigens.
Specifically what do Th1 CD4+ cells do?
Promote Ab-mediated immune responses. As a component of this activity these cells sere as helper cells for B cell activation and supply cytokine signals that stumulate B cells to produce Ab's that will eliminate extracellular pathogens.
What are two mechanisms pathogens can use to get around the body's immune responses?
Evasion and subversion of the immune system- pathogens can avoid or alter the the immune response produced by the host. Immunodeficiency disease- Inherited defects in genes for components of the immune system
What is a hypersensitive immune reaction?
An over reaction of the immune system that lead to discomfort , local tissue damage, widespread inflammation. Ex. allergic response
What happens in a graft rejection?
Since most individuals express different MHC molecules on their cells transplanted tissue is seen as non-self by the immune system and is attacked.
What is an autoimmune reaction?
Immune responses to self-tissue
How can you manually manipulate the immune response?
Are antigen presenting cells in the innate immunity or adaptive immunity?
Innate- These cells
What is a clonal section?
When a lymphocyte is stimulated by binding of its receptor to its cognate antigen the lymphocyte is activated to proliferate giving rise to many new lymphocytes that bear an identical antigen-receptor specificity.
What is somatic recombination?
The immunoglobulin genes that code for lymphocyte receptors consist of a series of gene segments that are randomly recombined to generate complete coding regions for antigen-binding portions of the lymphocyte receptor molecules. This random process is called somatic recombination.