Immunology lecture 1

White blood cells. Use circulatory system for transport and enter tissues where they function.

• Include:
• neutrophils, basophils, eosinophils, monocytes, lymphocytes

• Produced in bone marrow.
• 50-70% of all blood leukocytes.
• Number changes dramatically during infection.

• Functions:
• Phagocytosis
• Release chemicals involved in inflammation (vasodilators, chemotaxins, etc.)

Produced in bone marrow.

• Functions:
• Carry out functions in blood similar to mast cells.
• Release histamine & other dchmicals involved in inflammation.

Produced in bone marrow.

• Functions:
• Destroy multicellular parasites.
• Participate in immediate hypersensitivity reactions

• Produced in bone marrow.
• Precursor to all tissue macrophages.

• Functions:
• Monocytes circulate in the bloodstream for about one to three days and then typically move into tissues throughout the body. Half of them are stored as a reserve in the spleen in clusters in the red pulp.
• Monocytes which migrate from the bloodstream to other tissues will then differentiate into tissue resident macrophages or dendritic cells.
• Monocytes and their macrophage and dendritic cell progeny serve three main functions in the immune system. These are phagocytosis, antigen presentation and cytokine production.

Mature in bone marrow (B cells and NK cells) and thymus (T cells). Activated in peripheral lymphoid organs.

• Functions:
• Serve as recognition cells in specific immune responses and are essential for all aspects of these responses.

• Functions:
• Initiate antibody-mediated immune responses by binding specific antigent to the B cell's plasma membrane receptors, which are immunoglobulins.
• During activation are transformed into plasma cells, which secrete antibodies.
• Present antigen to helper T cells.

• Functions:
• Bind to antigens on plasma membrane of target cells (virus infected cells, cancer cells, and tissue transplants) and directly destroy the cells.

• Functions:
• Secrete cytokines tha thelp to activate B cells, cytotoxic T cells, NK cells, and macrophages.

Capable of recognizing and responding to virally-infected host cells by killing them.

• Functions:
• Bind directly and nonspecifically to virus-infected cells and cancer cells and kill them.
• Function as killer celle in antibody-dependent cellular cytotoxicity (ADCC).

Produced in peripheral lymphoid organs; differnetiate from B cells during immune responses.

• Functions:
• Secrete antibodies.

• Produced in bone marrow; reside in almost all tissues and organs; differentiate from monocytes.
• Have pseudopods.
• Participate in apoptosis and removal of dead cells.

• Functions:
• Phagocytosis.
• Extracellular killing via secretion of toxic chemicals.
• Process and present antigens to helper T cells.
• Secrete cytokynes involved in inflammation, activation and differentiation of helper T cells, and systemic responses to infection or injury (the accute phase response).

• Produced in almsot all tissues and organs; microglia in the CNS.
• Capable of recognizing and responding to smaller pathogens and their molecular products (ex: viruses).

• Functions:
• Same as macrophages.
• Phagocytosis.
• Extracellular killing via secretion of toxic chemicals.
• Process and present antigensvto helper T cells.
• Secrete cytokynes involved in inflammation, activation and differentiation of helper T cells, and systemic responses to infection or injury (the accute phase response).

Produced in bone marrow; reside in almost all tissues and organs; differentiate from bone marrow cells.

• Functions:
• Release histamine and other chemicals involved in inflammation.

• Secreted protein messengers that regulate host cell division and function in both nonspecific and specific immune defenses.
• Link the components of the immune system together.

Exaggerated specific responses to non-pathogenic environmental allergens.

Any exaggerated specific responses that are tissue damaging.

Specific, exaggerated and destructive responses to self-antigens.

Variable responses to self such as in cancers.

Strong barriers to organ and tissue transplantation.

Intact skin, hair, sweat, saliva, tears, mucus, respiratory tract (cilia, trachea, lungs), GI tract (stomach, intestines, esophagus).

Local response to infection or injury.

• Functions:
• Destroy or inactivate invaders and to set the stage for tissue repair.

• Sequence of Events:
• 1. Entry of bacteria; injury to tissues causes release of chemicals to initiate the following events.
• 2. Vasodilation of the microcirculation in the infected area, leading to increased blood flow.
• 3. Large increase in protein permeability of the capillaries and venules in the infected area, with resulting diffusion of protein and filtration of fluid into the interstitial fluid.
• 4. Chemotaxis: Movement of leukocytes from the venules into the interstitial fluid of the infected area.
• 5. Destruction of bacteria in the tissue either through phagocytosis or by other mechanisms.
• 6. Tissue repair.

• Innate, Non-Specific Defenses:
• Physical and/or chemical barriers
• Mollecular (complement, cytokines, chemokines, acute phase proteins)
• Cellular (phagocytic cells, NK cells)

• Acquired, Adaptive, Specific Defenses:
• Mollecular (antibodies)
• Cellular (lymphocytes: naive, effector and memory lymphocytes)