Introduction to Immunology PDF

INTRODUCTION TO IMMUNOLOGY VEM-021 (Fundamentals of Immunology) Gerry Joey P. Laurito II, DVM Assistant Professor-I Objectives ü Describe immunity & the different physical barriers ü Describe and differentiate innate and adaptive immunity ü Describe and differentiate antibody and cell me...

INTRODUCTION TO IMMUNOLOGY VEM-021 (Fundamentals of Immunology) Gerry Joey P. Laurito II, DVM Assistant Professor-I Objectives ü Describe immunity & the different physical barriers ü Describe and differentiate innate and adaptive immunity ü Describe and differentiate antibody and cell mediated immunity. Immunity / The Defenders ü Interlinked ü Redundancies ü Regulatory Mechanisms ü Simultaneous responses ü Adaptive Immunity / The Defenders Physical Barriers ü Intact skin ü Commensal organisms/ Microbiota ü Respiratory ü Gastrointestinal ü “Self-cleaning” processes: Coughing Sneezing Vomiting Diarrhea Urine flow Innate Immunity ü Activated immediately/ “on call” ü Responses are generic ü Sentinel cells ü Inflammation ü “Hard-wired” subsystems Adaptive Immunity ü Smart responses ü Ultimate defense of the body ü Not only destroys but retains memory ü Intracellular/ Endogenous vs. Extracellular/ Exogenous invaders ü Long-lived populations of memory T and B cells persist for a long time Adaptive VS. Innate Immunity Adaptive VS. Innate Immunity Cellular-mediated vs. Humoral ü Intracellular/ endogenous invaders ü Body fluids (humor) (intracellular bacteria, viruses, protozoa) ü Extracellular/ exogenous invaders (mostly bacteria, fungi, protozoa, ü T cells helminths) ü Cytotoxic T cells- abnormal cell ü B cells- produces antibodies ü Helper T cells- provide a signal for adaptive immune responses ü Regulatory T cells- regulates immune response Antibody mediated Immunity Antibodies– protective molecules from serum ü Highly specific and bind only to the antigen and ensure its destruction. ü Antibodies bind- “neutralize” the toxin so that it is no longer toxic. Antigen – a foreign substance that stimulates an adaptive immune response ü Animal B cells are stimulated to produce antibodies that bind to antigens and ensure their destruction. Antibody mediated Immunity Antibody mediated Immunity Single-dose toxin ü 1 week lag period ü Corresponding B cells populations grow and begin to produce antibody ü The amount of antibody/ amount of protection conferred during the first primary response is relatively small since there are few antibody B- producing B cells. Antibody mediated Immunity 2nd dose of toxin / 2nd response ü lag period is shorter ü The amount of antibodies rises to a high level before declining slowly ü Months or years – antibody detection ü B cell’s ability to remember previous exposure to antigen. ü “Anamnestic response” Antibody mediated Immunity ü Antibodies produced after repeated injections can better bind and neutralize the toxin than those produced in the early immune response. ü Repeated injections generate memory cells and form the basis of Vaccination. ü A secondary response can also be induced even though the response of the animal to the first antigen was so weak as to be undetectable. Cell mediated Immunity ü Survives only a few days before being rejected and destroyed by the recipient. ü Foreign cells are recognized by the immune system. ü Mediated by cytotoxic T cells- identifies and destroys the abnormal cell Cell mediated Immunity ü Graft rejection, like antibody formation- is a specific adaptive rejection. ü It also involves the generation of long- lived memory cells ü It cannot be transferred from a sensitized to a normal animal by serum. ü Only by living T cells- found in your spleen, lymph nodes or blood. Mechanism of Adaptive Immunity ü Antibody-mediated responses and cell- mediated systems. ü Pass system ü Trapped and processed- Dendritic/ macrophages ü B cells or T cells ü Next time, same exposure, cells will respond faster and with great efficiency. Any questions?