Introduction To Immunity PDF

Dr. Sanaa Atef Abdallah  Provide students with the terminology of immunology  Define the normal immune system.  Define immune response.  Explain the protective role of the immune system against microbial infections (adaptive immunity).  Intended learning outcomes:- After this topic the stude...

Dr. Sanaa Atef Abdallah  Provide students with the terminology of immunology  Define the normal immune system.  Define immune response.  Explain the protective role of the immune system against microbial infections (adaptive immunity).  Intended learning outcomes:- After this topic the student should be able to:-  Define immunology, immune system and immune response  Explain types of immune response  Define tolerance,hapten and antigenic epitopes  Define antigen and enumerate types of antigen  Explain characters of antigen  Differentiate between Humoral immune response and cell mediated immune response Lecture outlines:- Immunology Immunity Immune response Tolerance  Antigenic Epitopes  Characters of antigen  Types of antigen  Humoral immune response  Cell mediated immune response(CMI)  Immunology:  is the study of the processes by which the body defends and maintain itself against invasion by foreign agents  Immunity Adaptive Innate Humoral CM  Immune response Ag Humoral Ab Cell mediated Tolerance  Immune response Humoral Cell-mediated Antibodies Special Immunoglubulins cells Tolerance Tolerance (immune unresponsiveness), on the other hand, is an essential protective mechanism that prevents the immune system to attack its normal body components. In many ways, the immune system might be illustrated as an organized city in which foreigners are expelled and good citizens are tolerated, but those who "deviate" are also eliminated. City of this type usually requires an identification system so that foreigners are detected and dealt with. Antigenic Epitopes: Antigenic Epitopes: Immune cells do not interact with or recognize foreign molecule except if there is/are discrete sites on the immunogen called epitopes or antigenic determinants.  An epitope serves as the smallest unit of an antigen that is capable of eliciting an immune response.  One antigen may have several identical or different epitopes, for example a protein molecule has many different antigenic epitopes.  Hapten Low molecular weight Simple biochemical structure Hapten No Immune response but if unite with protein in IR against both the body   Characters of antigen Large molecular weight (protein) Complex biochemical structure Foreign Route of administration Dose  Types of Antigen Heterophile antigen   IR against it and another antigen Example: Streptococcal tonsilitis, the immune response will be against Streptococcus and against myocardium  Causing rheumatic fever  Human antigens (graft) Auto Ag Graft Iso Ag Identical twins Allo Ag Non-Identical twins (Homo) Xeno Ag Human (Animal) Cells of the Immune Response Bone Marrow STEM CELL WBCs RBCs Platelets  WBCs Granulocytes Agranulocytes Neutrophils Monocytes Eosinophils Lymphocytes Basophils Neutrophils Acute infection Eosinophils Allergy Basophils Allergy Monocytes Lymphocytes Dendritic Humoral immune response  TH TH Cell mediated immune response(CMI) TH Effector Tc (CD8) kill target cells by one of two ways: 1. The perforin pathway Binding of Tc to the target cell triggers the releasing of perform and granzymes. Perforins form pores in target cells allowing the granzymes to enter the cell, where they induce programmed cell death (apoptosis). 2. The Fas-FasL Pathway: Activated Tc has a protein called Fas ligand on its surface which interact with the Fas on the target cell surface causing cell death. Antigen  MHC (HLA): Human Leukocyte Antigens are cell surface expressed molecules that play a major role in presentation of antigens and play a critical role in the success or failure of transplants MHC located on the short arm of chromosome 6. Three of these genes are known.  MHC (HLA): 1. Class I MHC genes: Expressed on he surface of all nucleated cells. The major function of it, is presentation of antigens to TC cells 2. Class II MHC genes Expressed on Antigen presenting cells. The major function of it is presentation of antigens peptides to TH cells 3. Class III MHC genes Encode various secreted proteins that have immune functions as complement C4, C2 and inflammatory cytokines as TNF and HSP  MHC ( HLA) complex MHC Class I Class II Class III Class C2 C4 Region A B C DP DQ DR TNF On All Nucleated Cell On APC T Cell TC TH TH2 TH1 Primary LO T lymphocytes B lymphocytes TR LD MALT Secondary LO  Class I VS Class II MHC Points of Class1 MHC Class-II MHC comparison Types They include: A,B,C They include: DP, DQ, DR Found on certain cells e.g. Site Found on all nucleated cells T-cells &APCs Complexes with the Ag on target cells Complexes with antigen on Function (virus infected cell, tumor cell & graft APC to stimulate TH. cell) to stimulate Tc  InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. The innate and adaptive immune systems. [Updated 2020 Jul 30]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279396/ Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. The major histocompatibility complex and its functions. Available from: https://www.ncbi.nlm.nih.gov/ books/ NBK27156. Silverstein, Arthur M. (2009). A History of Immunology (2nd ed.). Academic Press. p. 293. ISBN 9780080919461. For any questions feel free to contact me mail [email protected] Dr. Sanaa Atef Abdallah Lecturer of microbiology & immunology