Immunological reactions and immune response ppt

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  • 1. Any substance which introduced parenterally into the body, stimulates the production of an antibody with which it reacts specifically and in an observable manner ANTIGEN

2. 1. Induction of an immune response 2. Specific reaction with antibodies 3. 1. Induction of an immune response 2. Specific reaction with antibodies Complete antigen Hapten 4. The smallest unit of antigenicity is known as epitope Smallest area 4-5 amino acids or monosaccharide residues Specific chemical structure, charge and configuration Antibodies are specific for epitopes 5. Antibodies or Immunoglobulins Immunoglobulin Provides Structural and Chemical concept Antibody Is a biological and functional concept All antibodies are Immunoglobulins, but all Ig may not antibodies 6. Antigen-Antibody Reaction The reaction serve several purposes In vivo In vitro Immunity , Autoimmune diseases Serological reactions 7. Primary Secondary Tertiary 8. The reaction is specific Entire molecule react and not fragment There is no denaturation of Ag or Ab Combination occurs at the surface Combination is firm but reversible Both Ag and Ab participate in the reaction Ag-Ab can combine in varying proportions 9. In terms of MASS(mg nitrogen ) or as units or titer 10. Highly sensitive False negative reactions are absent or minimal Sensitivity Highly specific False positive reactions are absent or minimal Specificity 11. Precipitation reaction Agglutination Complement fixation test Neutralisation test Opsonisation Immunoflurorescence Radioimmunoassay Enzyme Immunoassays Chemiluminescence immunoassay Immunoelectroblot Techniques Immunochromatographic tests Immunoelectronmicroscopic tests 12. Precipitation occurs Electrolyte Antibody Soluble antigen Precipitation reaction 13. Flocculation Medium The amount of precipitation influenced by relative proportion of Ag and Ab Mechanism of precipitation - Prozone - Zone of equivalence - Postzone Precipitation reaction 14. Precipitation reaction Application: Both qualitative and quantitative tests Very sensitive in detecting antigens Forensic application 15. Precipitation reaction Ring test Slide test Tube test Immunodiffusion Electroimmunodiffusion 16. Immunodiffusion 1. Single diffusion in one direction 2. Double diffusion in one direction 3. Single diffusion in two dimension 4. Double diffusion in two dimension 5. Immunoelectrophoresis 17. Radial Immunodiffusion (Mancini) Interpretation Diameter of ring is proportional to the concentration Quantitative Ig levels Screaning sera for Abs to influenza virus among others Method Ab in gel Ag in a well Ag Concentration Diameter2 AgAgAgAg Ab in gel 18. Double diffusion in 2 dimensions 19. First do electrophoretic separation of a mixture of soluble antigens in a gel medium. Individual antigens are detected using an antiserum containing antibodies for all antigens in the mixture diffused at a right angle to the direction of electrophoresis. 20. Antigen applied to wells; Separation by charge Antibody in trough, Protein diffusion in gel Precipitin complex indicating identity and recognition 1 2 3 Example: Human sera probed with rabbit anti-human antibodies AgAg 21. Development of precipitin lines can be speeded up by electrically Various methods A. One dimensional double electroimmunodiffusion Counter immunoelectrophoresis B. One dimensional single electroimmunodiffusion Rocket electrophoresis 22. A. One dimensional double electroimmunodiffusion [Counter immunoelectrophoresis] Clinical application: detecting various Ags; -fetoprotein in serum& specific Ags of Cryptococcus & Meningococcus in the CSF 23. Slide agglutination Tube agglutination Antiglobulin test Passive agglutination Haemagglutination Applications 24. + Patients RBCs Coombs Reagent (Antiglobulin) 25. Patients Serum Target RBCs + Step 1 + Coombs Reagent (Antiglobulin) Step 2 26. The ability of Ag-Ab complex to fix complement is made use of in CFT Looking for evidence of infection. The test requires five reagents and is carried out in two steps. The Wassermann test is one form of complement fixation test: serodiagnosis of syphilis. 27. Based on the concept that antibodies can neutralize biological activity of many pathogens and their toxins Viral neutralisation test Toxin neutralisation test 28. Heat labile substance Heat stable substance Complement Bacteriotropin Opsonin 29. Albert Hewett Coons (19121978) Direct Immunofluorescence test Indirect Immunofluorescence test 30. 1957 Berson and Yalow Application Hormone - Drugs - Tumour markers - IgE - Viral antigens Nobel Prize 1977 31. Sensitivity - Simplicity - Economy - Absence of radiation - Availability of test kit - Facility for automation 32. Includes all assays based on measurement of enzyme labeled antigen, hepten or antibody 2 types Homogeneous EIA Heterogeneous EIA 33. Technique involves the use of an IMMUNOSORBENT Usually done using 96-well microtitre plates suitable for automation Rota virus - Anti -HIV antibody test 34. Refers to a chemical reaction emitting energy in the form of light Chemiluminescent compounds - LUMINOL - ACRIDINIUM ESTERS The method has been fully automated 35. Combine the sensitivity of EIA with much greater specificity Combination of 3 separate procedures Separation Blotting EIA or RIA 36. One step Qualitative - Simplicity - Economy - Reliability HBSAg detection 37. The key is our ability to produce more than 108 distinct antibodies and more than 1012 T-cell receptors 38. The immune system has 2 arms Innate immunity Adaptive immunity 39. 1. Humoral (AMI) 2. Cellular (CMI) 40. Humoral Immune response(AMI) Entry Processing Secretion 41. Lag phase Log phase Plateau or steady state Phase of decline 42. Non- immune phase Phase of immune elimination 43. Immune response to an antigen is brought about by 3 type of cells Lymphocytes APC Effector cells 44. Ranjiths 45. Ranjiths 46. Genetic Age Nutrition Route of administration Size & number of doses Multiple antigens Adjuvants Immunosuppres sive drugs Effect of antibody 47. Specific immune response that do not involve antibodies. Delayed hypersensitivity Immunity in infections Transplantation immunity Immunological surveillance Autoimmune disease Scope of CMI 48. Antigenic stimulus Only T-cell dependant antigens lead to CMI T-cell bears specific receptor on its surface T cells recognize antigens only when presented with MHC molecules Helper T-cells Cytotoxic T-cells 49. Peptide mediators or intracellular messengers which regulate immunological, inflammatory and reparative host responses They are potent hormone like substances Produced by lymphocytes, macrophages, platelets & fibroblasts 50. Interleukins Colony stimulating factors Tumour necrosis factors Interferons Others 51. Macrophages & other cells IL-1 and IL-1 Proliferation & differentiation of T, B and other cells Pyrogenic Induce acute phase proteins Bone marrow cell proliferation Interleukin-1 52. T-cells Powerful modulator of the immune response Promote growth and differentiation of T and B cells Cytotoxicity of T and NK cells Secretions of other lymphokines Interleukin-2[TCGF] 53. Stimulates the growth & differentiation of pleuripotent stem cells in the bone marrow Responsible for adjusting the rate of production of blood cells Treating hematopoietic dysfunctions in infections & malignancies Colony stimulating factors 54. Induce hemorrhagic necrosis in certain tumours TNF and TNF Cachectin is TNF Tumour necrosis factors 55. Originally identified as antiviral agents Interferons