What is Innate Immunity?
1) The cellular and biochemical defense mechanisms that are in place even before infection
2) Characterized by rapid response to initial infection
3) Consists of physical and chemical barriers located in the skin, epithelial membranes and blood
What is Adaptive Immunity
1) "adaBT" Also called specific/acquired immunity 2) develops as response to infection
What are the three characteristics of the AdaBTive Immunity?
Specificity; Memory ;Diversity
What is a cytokine?
Cytokines are a large group of secreted proteins that regulate and coordinate activities of both the innate and adab
Name some of the functions of Cytokines (3)
1) Growth and differentiation of immune cells
2) Activation of effector molecules, phagocytes and lymphocytes
3) Directed movement of immune cells from blood to tissues
Individuals become immune to exposure to disease by the transfer of serum or lymphocytes from a specifically immunized individual
What is the process by which a person obtains passive immunity?
The process by which molecules coat antigens and make them easier to be phagocytosed
The part of an antigen that lymphocyes respond to. Determinants
What is Diversity? Which type of immunity is it associated with?
1) Variability in the strucutres of the antigen binding sites of lymphocytes.
2) Associated with Adaptive Immunity
Each exposure to an antigen generates long-lived memory cells specific for the antigen, which are more numerous than the naive lymphocytes.
The process by which lymphocytes bind to an antigen and proliferate
Self tolerance the ability for the immune system to NOT attack cells marked self
The cells that specifically recognize and respond to foreign antigens. (Mediators of humoral and cell mediated immunity)
The only cells capable of producing antiBodies
Recognize extracellular soluble and cell surface antigens
Differentiate into anti-body secreting plasma cells.
The cells of cell mediated immunity
Recognize the antigens of intracellular microbes
Also help Phagocytes to destroy microbes or infected cells
Recognize peptides derived from foreign proteins that are bound to host proteins (MHC)
Call for help "messenger" molecules
Secrete cytokines that stimulate the differentiation of T cells, activate B cells, macrophages, and other leukocytes.
Cytolytic T Lymphocytes
Kill Cells that produce foreign antigens
Regulatory T Cells
Function mainly to inhibit immune responses
Antigen presenting cells. Capture antigens and present them to lymphocytes.
Dendritic Cells. Capture microbial agents (antigens) that enter from the external environment, transport them to lymphoid organs, and present the antigens to naive T lymphocytes to intiate immune responses; most important APC; link innate/adaBTive immune response; phagocytotic; located in lymphoid tissues, mucosal epithelium and organ parenchyma; has a hematopoietic derivation
Mediate the elimination of antigens
What are the two main innate immune responses to microbes?
2) Antiviral defense
1) The process of the recruitment of leukocytes and plasma proteins from the blood, their accumulation in tissues and their activation to destroy microbes
2) Macrophages, cytokines, dendritic cells, monocytes, neutrophils
Consists of a cytokine mediated reaction in which cells acquire resistance to a viral infection and killing of virus infected cells by specialized cells of the innate immune system. Natural Killer cells.
What are the three main strategies the adaptive immune system uses to combat most microbes?
1) Antigens (Bind to pathogen, block them from binding to cells, mark them for destruction)
2) Phagocytosis (Ingest and kill microbes; antibodies and helper T cells enhance microbidicidal abilities of the phagocytes
3) Cytotoxic T lymphocytes kills cells/antigen that antibodies and phagocytes can't.
Function of Dendritic Cells in the Innate Immune System
1) Phagocytose microbes and present their antigens on the plasma membrane
2) Travel to draining lymph nodes where T lymphocytes circulate
3) Also work in the spleen
Functions of Macrophages
1) Ingest and kill microbes, dead and dying host cells
2) Secrete cytokines that act on endothelial cells for recruitment of more monocytes, leukocytes etc.
3) Serve as APCs that displays antigens for T Cell activation
4) Promote repair of damaged tissues via new blood vessel growth (angiogenesis) mediated by cytokines
The process by which cytokines stimulate macrophages to promote tissues remoldeling and repair.
What are some examples or granulocytes? (4)
Capture antigens, present them to lymphocytes and provide signals that stimulate the proliferation and differentiation of lymphocytes
Types of APCs
Dendritic cells; Macrophages and B-lymphocytes (APC for CD4+ helper T cells)
Cytotoxic T-lymphocytes; CD8+ effector cells that recognize antigens on any type of nucleated cell
cells whose function is to eliminate the antigen
cell whose function it is to mediate rapid and enhanced responses to subsequent exposure
What is the importance of cytokines for B/T cell (naive) Survival?
if B/T cells do not get stimulated, they die; (IL-7) promotes survival and low level cycling of naive T-cells
Innate Lymphoid Cells; subset of bone marrow derived cells; lymphoid morphology/effector functions like T-cells; lack T-cell antigen receptors; functions: Early defense, recognize stressed/damaged cells, help eliminate cells.
Natural Killer cells; ILC; secrete IFN gamma; kills infected and damaged cells
What are the peripheral, secondary, lymphoid organs of the B-Cells and T-Cells?
B-Cells (Spleen/Lymph nodes)/ T-Cells (Peripheral organs and tissues)
Site of T-Cell maturation;
Medullary Thymic Epithelial Cells
Plays a special role in presenting self-antigens to developing T cells and cause their deletion (important for self tolerance)
Active vs. Passive Immunity
1) Encounter with antigen is both specific and confers memory. 2) Passive Immunity, serum antibodies from an immune individual. Is specific, but does not confer memory.
What are the three stages of the immune response?
1) Recognition (Activation of innate cells and inflammatory response) 2) Effector (activation of specialized APCs to induce adaptive immunity 3) Regulation (Lymphocytes activated by antigen give rise to clones of Ag specific effector cells.
Where is IL-6 produced by? What effects does it have in the body?
Produced by macrophages in response to interaction with pathogens. Stimulate the liver to release MBL, C-reactive proteins, SP-A, SP-D, Serum amyloid proteins, fibrinogen. MBL and C-reactive protein act as opsonins and activate complement.