Immunology Lecture Notes 2024-2025 PDF

Immunology Adaptive Immunity  Adaptive Immunity The Adaptive, or Acquired immunity (specific immune system) : is an immunity that occurs after exposure to an antigen either from a pathogen or a vaccination. This part of the immune system is activated when the innate immune...

Immunology Adaptive Immunity  Adaptive Immunity The Adaptive, or Acquired immunity (specific immune system) : is an immunity that occurs after exposure to an antigen either from a pathogen or a vaccination. This part of the immune system is activated when the innate immune response is insufficient to control an infection. There are two types of adaptive responses: 1- The cell-mediated immune response, which is carried out by T cells, 2- The humoral immune response, which is controlled by activated B cells and antibodies. The Characteristics of Adaptive Immunity. Third line of defense (after surface barriers and innate immunity) Compared to inflammation it is: Slower, more specific, and longer lasting. Acquired after contact with antigens (so also called acquired immunity) Adaptive response usually initiated by cells of innate immune system, primarily phagocytes. Recognizes specific antigens. Provides memory to fight pathogens when they are encountered again. The Components of Adaptive Immunity: Antigen presenting cells (APCs) (macrophages or other phagocytes) process invading pathogens. Present portions of engulfed pathogens to lymphocytes in peripheral lymphoid tissue. Lymphocytes mediate adaptive immune response (primary cells responsible) B lymphocytes - responsible for humoral immunity. T lymphocytes - responsible for cell-mediated immunity. There are two major branches of the adaptive immune responses: humoral immunity and cell-mediated immunity. Humoral Immunity: humoral immunity involves the production of antibody molecules in response to an antigen and is mediated by B-lymphocytes. (Also called antibody mediated immunity) based on antibody activity. Cell Mediated Immunity: CMI involves production of cytotoxic T- lymphocytes, activated macrophages, activated NK cells and cytokines in response to an antigen and is mediated by T-lymphocytes.(Also called cell mediated immunity) based on action of specific kinds of T lymphocytes. The Memory cell: The role of memory cell to prepare the body for further contact with the same Ag. Memory cells recognize Ag and respond by secondary immune response. It is faster cycles of division take short time. It is greater in amplitude instead of one cell in primary response there is a whole clone of cells and so amount of Abs is higher. It is the basis of life – long immunity associated with same infection measles, whooping cough. It is the basis of vaccination.