Instructions: Make a powerpoint slide for each of the 5 items below and post to the discussion board.
Describe elements and processes of innate and adaptive immunity.
Explain the mechanisms of inflammation.
Characterize immunity, antigens, immunogens, and antibodies.
Compare and contrast B Cells and T Cells.
Compare and contrast the immune function in neonates and geriatric population. APA Style.
Innate and Adaptive Immunity
Innate immunity is the first line of defense against pathogens. It involves physical and chemical barriers like skin and stomach acid as well as sentinel cells that recognize broadly shared molecular patterns in pathogens. If pathogens breach these defenses, inflammation occurs and phagocytes are recruited to destroy invaders (Medzhitov & Janeway, 2000). Adaptive immunity develops later via antigen presentation and clonal selection or expansion of B and T cells. It produces immunological memory allowing faster and stronger responses upon reexposure. Adaptive immunity involves B cells producing antibodies and T cells that directly destroy infected cells or regulate immune responses (Murphy et al., 2008).
Mechanisms of Inflammation
Inflammation is initiated by tissue damage or pathogen presence. Cells release inflammatory mediators like histamine, bradykinin, prostaglandins, and leukotrienes. These cause increased blood flow, vascular permeability, and pain while attracting phagocytes. Cytokines like interleukin-1β (IL-1β), tumor necrosis factor α (TNFα), and interleukin-6 (IL-6) signal the acute phase response and recruit additional immune cells. Phagocytes like neutrophils and macrophages arrive and destroy pathogens through phagocytosis and release of reactive oxygen species and proteolytic enzymes. Resolution involves cytokines that limit inflammation and promote healing (Medzhitov, 2008).
Immunity, Antigens, Immunogens, and Antibodies
Immunity refers to protection against pathogens. An antigen is any substance that triggers an immune response through binding of antibodies or T cell receptors. An immunogen is an antigen capable of eliciting an adaptive immune response with antibody production or immunological memory. Antibodies are Y-shaped proteins called immunoglobulins that are produced by plasma cells. They recognize antigens through their antigen binding sites with high specificity and affinity. Antibodies neutralize pathogens, mark them for destruction by other immune cells, and prevent reinfection by retaining immunological memory (Murphy et al., 2008).
B Cells and T Cells
B cells and T cells are the two major lymphocyte types involved in adaptive immunity. B cells mature in the bone marrow and express immunoglobulin receptors on their surface that allow them to recognize specific antigens. Upon activation, they proliferate and differentiate into either plasma cells that secrete antibodies or memory B cells. Antibodies neutralize extracellular pathogens. T cells mature in the thymus and have T cell receptors that recognize antigen fragments bound to major histocompatibility complex (MHC) molecules on antigen presenting cells. There are cytotoxic T cells that directly kill infected cells and helper T cells that regulate immune responses through cytokine secretion (Murphy et al., 2012).
Neonatal and Geriatric Immunity
The neonatal immune system is relatively naive and relies more on innate immunity. Levels of maternal antibodies wane by 6 months. Vaccination responses are weaker due to an immature adaptive system. In contrast, the aging immune system shows decreased naive T and B cell production, reduced diversity of lymphocyte receptors, chronic antigenic stimulation causing T cell exhaustion, and elevated proinflammatory cytokines. This leads to weaker responses to new pathogens and less effective responses to vaccination (Weiskopf et al., 2009; Shaw et al., 2013). Caregivers should be aware of these differences to best support immune protection.