ACQUIRED IMMUNITY Overview of the components of acquired

ACQUIRED IMMUNITY - Overview of the components of acquired immunity. - Overview of the different acquired immune responses. - Definition of pathogens and types of antigens and antigenic determinants. Dr. Sultan Alsharif & Dr. Iman Thabet

Acquired Or Adaptive Immunity Specific resistance Acquires during life time Increases with repeated exposures Has memory Dr. Sultan Alsharif & Dr. Iman Thabet

Types of Acquired immunity ACTIVE PASSIVE Dr. Sultan Alsharif & Dr. Iman Thabet

Active Developed as a result of an antigenic stimulus Involves the synthesis of antibodies Production of immunologically active cells Dr. Sultan Alsharif & Dr. Iman Thabet

Passive Resistance that is transmitted to a recipient in a readymade form Preformed antibodies are administered Dr. Sultan Alsharif & Dr. Iman Thabet

Dr. Sultan Alsharif & Dr. Iman Thabet Adaptive immunity mechanisms: • Cell-mediated immune response – T cells – eliminate intracellular microbes that survive within phagocytes or other infected cells • Humoral immune response – B cells – mediated by antibodies – eliminate extra-cellular microbes and their toxins Plasma cell (Derived from B cells , produces antibodies)

Cell-Mediated Immune Response Dr. Sultan Alsharif & Dr. Iman Thabet

What are MHC & APC Major Histocompatibility Complex (MHC) MHC proteins, mark a cell as self The two classes of MHC proteins are: � Class I MHC proteins – found on virtually all body cells � Class II MHC proteins – found on certain cells in the immune response The main function of MHC molecules is to bind to peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T-cells Dr. Sultan Alsharif & Dr. Iman Thabet

Antigen-Presenting Cells �B cells � Dendritic cells � Macrophages Dr. Sultan Alsharif & Dr. Iman Thabet

How do T cells know a cell is infected? Infected cells digest some pathogens and MHC proteins carry pieces to cell surface Antigen Presenting Cell (APC) Alerts Helper T cells infected cell MHC proteins displaying foreign antigens TH cell T cell with antigen receptors Dr. Sultan Alsharif & Dr. Iman Thabet