Chapter 7 Week 3 Immunity copy 2 (dragged).pdf

Adaptive Immunity Chapter 7 Third Line of Defence: Adaptive Immunity Often called the immune response or immunity. Consists of lymphocytes and serum proteins known as antibodies. Develops slower than inflammation; takes 7 - 14 days to respond. Adaptive immunity is specific. The lymphocytes &...

Adaptive Immunity Chapter 7 Third Line of Defence: Adaptive Immunity Often called the immune response or immunity. Consists of lymphocytes and serum proteins known as antibodies. Develops slower than inflammation; takes 7 - 14 days to respond. Adaptive immunity is specific. The lymphocytes & antibodies induced in response to infection are specific to the infecting microbe. - Our immune response has a memory, will act faster if reinfected again. Both our innate & adaptive immunity work together and are essential for complete protection against disease. Definitions (1/2) Antigens: the molecular targets of antibodies and lymphocytes T lymphocytes (T cells): thymus derived lymphocyte. Develop into various other cells that can identify & kill a target, regulate immune response, or suppress inappropriate immune responses. B lymphocytes (B cells): bone-marrow derived lymphocyte. Will develop into plasma cells that become factories for producing antibodies. Memory Cells: both T & B cells differentiate into memory cells, which are rapidly activated when a second infection occurs Definitions (2/2) Humoral Immunity: Antibodies circulate in the blood and defend against extracellular microbes and microbial toxins Cellular Immunity: T cells circulate in the blood and tissues and defend against intracellular pathogens (viruses) Active (acquired) Immunity: develops in response to antigens, and the individual develops antibodies to antigens (infection or vaccines) Passive (acquired) Immunity: happens when there is exposure to an infectious agent without having a pre-existing vaccine-induced immunity; another example is a newborn receiving maternal antibodies via the placenta or breast milk. Immunoglobulins (Antibodies) These terms are interchangeable; immunoglobulin is general, whereas antibody is more specific 5 classes of Immunoglobulins: - IgG: most abundant in the blood, most protective; crosses placenta & protects newborns for the first 6 months of life - IgA: found in the blood and bodily secretions - IgM: largest; first antibody produced during the initial response to antigens - IgE: specialized as a mediator for allergic responses and defence against parasitic infections - IgD: antigen receptor on the surface of early B cells Secretory (Mucosal) Immune System Lymphoid tissues that protect the external surfaces of the body. Antibodies present in tears, sweat, saliva, mucus, and breast milk. IgA is the dominant immunoglobulin. Primary and Secondary Responses Primary Response Secondary Response Initial exposure Subsequent exposure Latent period or lag phase More rapid B-cell differentiation is occurring Larger amounts of antibody are produced After 5 to 7 days, an IgM antibody for a specific antigen is detected Rapidity is the result of memory cells that require less further differentiation An IgG response equal or slightly less follows the IgM response IgM may be transiently produced, but IgG is produced in considerably greater numbers Pediatric and Geriatric Considerations Pediatric Immunity Sufficient IgM but deficient IgG & IgA responses Maternal antibodies provide protection within the fetal circulation and during the first months of life Geriatric Immunity Decreased T-cell activity (Thymus size is 15% of its maximum size) Thymic hormone production drops, as does the organ’s ability to mediate T-cell differentiation Decreased antibody response to antigens