Foundations of Immunology Flashcards
List the major cells involved in the innate and adaptive immune response system
Innate - epithelia barriers, phagocytes, dendritic cells, complement, NK cells
Adaptive - B lymphocytes - antibodies, T lymphocytes - Effector T cells
Describe the main role of the innate immune system
- Distinguishes between human cells and pathogens but not between pathogens
- Fast and immediate - first to come into play
- No memory: will produce same response
Describe the functions of natural killer cells
track down, engulf and destroy bacteria, other pathogens as well as own damaged or dead cells
Describe the process of phagocytosis and intracellular killing
- Movement of the phagocytes toward the microbe
- Attachment of microbes to phagocyte surface
- Endocytosis of microbe and formation of phagosome
- Fusion of microbe with lysosome
- Killing of microbe through digestion by enzyme
- Discharge of waste material
Define the primary and secondary lymphoid organs and their functions
Primary lymphoid organs - where blood cells are produced and recieve “early training” - require ability to interact with antigen
- bone marrow
- thymus
Secondary lymphoid organs - site of lymphocyte activation by antigen
- lymph nodes
- spleen
- mucosal immune system
- tonsils
Describe the fundamental properties of an adaptive immune response
- distinguishes between different pathogens based on shapes on the surface - antigens
- slower- can take a few days to develop
- immunological memory: cells remember
Describe the role of B-lymphocytes in immunity
activation and production of antibodies (Abs)
- involved in humoral immunity
- antibodies directed against antigens
- B cells produced and bone marrow is where they mature
- B cells express B cell receptors
- on activation differentiate into plasma cells with help of T helper cells
Describe the function of Antibodies
Neutralization - antibodies bind to surface structure of microbes preventing and blocking the entry or attachment of microbes to host cell surfaces (IgA)
Opsonization - antibodies also facilitate uptake of microbes by phagocytes including macrophages so they facilitate phagocytosis
Complement - component of the innate immunity which eventually leads to the direct lysis and destruction of the microbes, proteins activated in cascade which takes place on target cells
- occurs in 1 of 3 pathways: classic, alternative, lectin
- leads to production of membrane attack making a hole in target cell, eventually leading to direct lysis and destruction of these targets
Describe the different classes of antibodies
IgM- 1st the be produced
IgA - protects mucosal surfaces resistant to stomach acid
IgE - defends against parasites that cause allergies
IgD - unkown function
IgG - main type of antibody binds many kinds of pathogens ie. viruses, bacteria, fungi, protects body from infection
Describe the function of T-Lymphocytes
responsible for cell mediated immunity and assisting B cells
Cytotoxic T cells - with CD8+ receptors, killing by binding to infected cell, perforin makes holes in infected cell’s membrane and enzyme enters, infected cell is destroyed
Helper T cells - with CD4 + receptors, stimulate B cells to produce antibodies, cannot kill infected cells or pathogens
Describe the role of T helper 1 and T helper 2 lymphocytes in controlling the immune response
T helper 1 (MHC class 1) - found on virtually all nucleated cells, presents “virtually induced” peptides to CD8+ T cells and triggers cytotoxic response by binding to peptides or antigens
T helper 2 (MHC class 2) - found only on ‘professional antigen presenting cells’ - macrophages, presents exogenously produced Ag to CD4+ T cells by binding to specific components of peptides or antigens
Describe the complement system and its main function
- Direct lysis of cells (holes produced in pathogen)
- increase blood flow and act as chemo-attractants and recruit other immune cells to the site of infection to enhance the immune response (inflammation)
- facilitate and enhance phagocytosis (opsonisation)
Describe the role of cytokines as chemical messengers within thew immune system
- group of small proteins that are produced and secreted by immune and non immune cells in response to stimulus, pathogen
- communicate with other cells by binding to specific receptor
- effects are impaired in innate and adaptive immune response: ie differentiation, activation of phagocytes, chemotaxis, enhancing the cytotoxic activity of immune cells, many different types of cytokines with different biological effects
Describe the function of the lymphatic system
- removal of the extra fluid accumulated in tissues and bringing it back top the circulation (drainage of tissues)
- absorbs and transports fatty acids and fats to the circulatory system
- lymph picks up any pathogens in the tissue and passes them to the lymphoid organs where these pathogens interact with the suitable lymphocyte to induce immune response against this particular pathogen
