Lecture 1 Flashcards
What are the two types of immunity?
Innate and Adaptive
This is a substance that induces an immune response
Antigen
Explain Innate Immunity
First Line of Defense of the immune system, it does not display specificity or memory. It recognizes microbes, consists of: 1. skin,epithelial barriers 2. Phagocytic cell, dendritic cells, and macrophages 3. Blood proteins- complement system.
It is the decision maker- tells adaptive what to do
Explain Adaptive Immunity
Displays specificity and memory. Undergoes somatic recombination so very large. Has two subsets of immunity.
What are the two subsets of adaptive immunity?
Cell Mediated and Humoral
Explain what a cytokine is and its function
Large group of secreted proteins with diverse functions and structure which regulate and coordinate many activities of the cells of innate and adaptive. Cytokines aid in growth and differentiation of immune cells, and activate effectors functions of lymphocytes and phagocytes and direct movement of immune cells from blood into tissue.
This is a subset of a cytokine that controls cell migration and movement
Chemokine
Explain Humoral immunity
Mediated by B cells- antibodies principle defense against extracellular microbes. Ab’s recognize microbial antigens and they neutralize infectivity of microbes and target microbes for elimination with the help of helper T cells. In summary : Secretes ab’s that prevents infection and eliminate extracellular microbes
Explain Cell Mediated Immunity
Mediated by T lymphocytes. Work to destroy intracellular microbes/viruses. Destruction of microbes in phagocytes or killing of cells with killer T cells.
What is clonal selection?
A test batch of ab’s are made called BCR and are transported to the surface of a B cell to find its match antigen. When it recognizes a cognate antigen the B cell is triggered to double in size and divide. They develop before and independently of exposure to an antigen.
What happens to the lymphocytes initiated in a response?
They die off in the contraction phase and homeostasis is restored. A few lymphocytes become ag specific memory cells and may last for years after infection.
Father of Immunology?
Dr. Pasteur
Conferred by a host response to a microbe or microbial ag’s– what type of immunity is this?
Active
Conferred by adaptive transfer of antibodies or T lymphocytes specific for the microbe
Passive Immunity
Can active or passive immunity generate memory cells?
Active
What is the role of B lymphocytes?
Recognize soluble Antigens and to become Antibody secreting cells.
What is the role of T Helper Cells
Recognize antigens on the surface of APC’s and secrete cytokines which stimulate different mechanisms of immunity and inflammation.
What is the role of T Killer cells?
Recognize antigens on infected cells and kill them
What is the role of Regulatory T cells?
Suppress and prevent immune responses e.g self antigens
Phagocytes- Name two types and what they do
Neutrophils and Macrophages- ingest and destroy microbes and get rid of damaged tissues
What are the steps of phagocytosis?
- Recruitment of cells to the site of infection
- Recognition of and activation by microbes
- Ingestion of the microbes by phagocytosis
- Destruction of ingested microbes
Phagocytes also secrete cytokines
These types of cells have 3-5 connected lobes known as PMNL’s and are the most abundant wbc in circulation. They mediate the earliest phases of the inflammatory response.
Neutrophils
Neutrophils are stimulated by what?
G-CSF, an adult produces 1x10^11 per day
What cell is programmed for death at the time it enters tissue from blood
Neutrophils
Neutrophils contain what?
Azurophilic granules- lysozymes that contain enzymes and other microbicidal substances
How do neutrophils respond to yeast and fungi?
They bind to yeast and internalize them via phagocytosis and the phagosomes fuse with azurophilic granules.
When neutrophils encounter hyphae, they are not able to internalize them, and azurophilic granules are free to deliver their contents instead into the nucleus, which triggers chromatin decondensation and the
release of NETs.
• NETs contribute to the immobilization and killing of extracellular organisms, but at the cost of some tissue damage
What other types of cells are involved in the innate and adaptive immune responses that also have cytoplasmic granules and can protect against helminths and allergic diseases?
Mast cells, Basophils, Eosinophils
Bone marrow derived cell present in skin and mucosal epithelia with cytoplasmic granules that contain histamine and provide defense against helminths?
Mast Cells
Explain the mononuclear phagocyte system
Consists of specialized phenotypes of macrophages depending on the organ. Circulating monocytes and resident tissue macrophages. Cells of the macrophage lineage arise from commited precursor cells in the bonemarrow driven by monocyte/macrophate CSF, monocytes enter the blood circulation and migrate to the tissues to become macrophages- especially during inflammation
What are dendritic cells?
Cells from myeloid lineage in bone marrow, differentiate into classical DC’s, Plasmacytoid DC and Inflammatory DC - may arise from monocytes in inflamed tissues-Langerhaans cells may develop embryonically
What are APC’s
Antigen presenting cells capture microbial and other antigens and display them to lymphocytes and provide signals that stimulate the proliferation and differentiation of lymphocytes, dendritic cells and langerhans cells
