Cell-mediated Immunity

Chapter 7 The third line of defense in the human body is adaptive immunity, which consists of lymphocytes and antibodies. Unlike innate immunity and inflammation, adaptive immunity is inducible and develops more slowly. It is highly specific to the infecting microbe and provides long-term protection through memory. The innate and adaptive immune systems are interactive and complementary, working together for complete protection against infectious disease. Bullet points Cell-mediated immunity  Effector T cells include Tc cells, Treg cells, and T lymphokine-producing cells  Tc cells destroy abnormal cells  Tc cells induce target cells to undergo apoptosis  Th1 cells activate M1 macrophages for phagocytic and microbial killing functions  Th2 cells activate M2 macrophages for healing and tissue repair  Th17 cells recruit phagocytic cells Pediatric Considerations: Age-Related Factors Affecting Mechanisms of Self-Defense in the Newborn Child  Neonates often have transiently depressed inflammatory function  The T cell-independent immune response is adequate in the fetus and neonate  The T cell-dependent immune response develops slowly during the first 6 months of life  Maternal IgG antibodies protect the neonate for the first 6 months Geriatric Considerations: Age-Related Factors Affecting Mechanisms of Self-Defense in the Elderly  Elderly persons are at risk for impaired wound healing, usually due to chronic illnesses  T-cell function and antibody production are somewhat deficient in elderly individuals  Elderly individuals tend to have increased levels of circulating autoantibodies Course Objectives: Explain the process of infection, including transmission, colonization, and invasion. Infection occurs when harmful microorganisms, like bacteria or viruses, enter the body and start to multiply. These microorganisms can be transmitted from one person to another through direct contact, contaminated surfaces, or droplets in the air. Once inside the body, they can colonize specific areas, such as the respiratory tract or digestive system. From there, they can invade deeper tissues, causing damage and triggering the immune response. Compare bacterial, viral, fungal, and parasitic infections, including manifestations. Bacterial infections are caused by bacteria and can result in symptoms such as fever, cough, and skin infections. Viral infections are caused by viruses and can cause symptoms like runny nose, sore throat, and body aches. Fungal infections are caused by fungi and can lead to symptoms such as itching, redness, and rashes on the skin. Parasitic infections are caused by parasites and can cause symptoms like abdominal pain, diarrhea, and fatigue. Define and differentiate antigenic drift from antigenic shift. Antigenic drift is a gradual change in the antigenic properties of a virus due to genetic mutations over time, while antigenic shift is a rapid and major change in the antigens of a virus caused by the reassortment of genetic material from different strains. Explain how bacterial resistance to antibiotics occurs. Bacterial resistance to antibiotics occurs when bacteria develop mechanisms to withstand the effects of antibiotics, making the drugs ineffective against them. These mechanisms can include genetic mutations that prevent antibiotics from reaching their target, enzymes that inactivate antibiotics, or pumps that remove antibiotics from the bacteria. Differentiate between active immunization and passive immunotherapy. Active immunization involves the stimulation of the immune system to produce a long-lasting response by introducing a weakened or killed pathogen or its antigens, while passive immunotherapy involves providing preformed antibodies to individuals to confer immediate, but temporary, protection.