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Autoimmunity PowerPoint Presentation

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Description : Check out this medical PowerPoint presentation titled "Autoimmunity" by Dr Puneet Kumar Gupta.

This medical PowerPoint presentation talks about autoimmunity. Autoimmunity is a condition in which the immune system, which normally defends the body against foreign invaders such as viruses and bacteria, mistakenly attacks the bodys own healthy tissues. In other words, the immune system fails to recognize "self" from "non-self" and targets normal cells, tissues, or organs as if they were foreign invaders.

This can lead to a wide range of autoimmune diseases, such as rheumatoid arthritis, lupus, multiple sclerosis, type 1 diabetes, and many others. These diseases can affect various parts of the body and have a wide range of symptoms, depending on which tissues or organs are being attacked.

Tags : Autoimmunity, immune system, autoimmune diseases, rheumatoid arthritis, lupus, multiple sclerosis, type 1 diabetes

Published on : Mar 16, 2023 | Views : 925 | Downloads : 1

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Autoimmunity For MBBS (28/11/2017) By: Dr Puneet Kumar Gupta Assistant Professor, Microbiology 1
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Tolerance and Autoimmunity 9
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What is tolerance? Mechanisms to protect from potentially self reacting lymphocytes. Central tolerance: In primary lymphoid organs (BM & Thymus) Peripheral tolerance: Secondary Lymphoid tissue 10
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Mechanism of Central tolerance Negative selection (by apoptosis) Receptor Editing (Antigen receptor gene rearrangement) 12
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Mechanism of peripheral tolerance Ignorance: Never encounter Self Ag Anergy: unresponsiveness Self reactive T cell interact with APC but co-stimulatory signal blocked Immunomodulatory molecules like CTLA4 binding instead of CD 28 on T cell Phenotypic skewing: after activation via APC (with Self Ag)---Non pathogenic cytokines release Activated self reactive Tcell---Upregulation of Fas Ligand---apoptosis Regulatory T cells (TREG Cells)-can down regulate self reactive T cell (by IL-10, TGF-b) Sequestration of self Ag: lens protein 14
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Antigen can be Tolerogen or Immunogens Co-stimulatory molecules play an important role Tolerance is antigen specific 16
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Failure of tolerance Autoimmunity Failure of Tolerance to protect host from self-reacting lymphocytes Destruction of self proteins, cells, and organs by auto-antibodies or self-reactive T cells 3% to 8% of individuals in the industrialized world 17
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Factors responsible for promoting tolerance High dose of antigen Persistence of antigen Route of administration Adjuvents Low level of co-stimulators Presentation of antigen by immature/unactivated antigen-presenting cells (APCs) 18
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All together Autoimmunity may be due to immunological, Genetic, Viral, Drug induced, & hormonal mechanisms Number of immunological mechanism  all leading to abnormal B or T-cell production. Most instances Diseases by multiple mechanism  difficulty in Rx 21
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Mechanisms Antigenic alteration Sequestered Ag Cross reacting foreign Ag Molecular mimicry Polyclonal activation of B cell Forbidden clones Altered T or B cell function 24
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Antigenic alteration Neoantigen formation Physical- Irradiation, photosensitivity, cold allergy Chemical- Drug induced anemia, Lecopenia, thrombocytopenia Biological injury-Viral infection (infectious mononucleosis etc) intracellular pathogen 25
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Sequestered Ag Sequestered Ag: Self Ab present in closed system not accessible to immune system Lens protein Immunological tolerance not established during foetal life Penetrating injury---leak of lens protein—immune response—injury to other eye 26
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Sequestered Ag Sperm Ag—Puberty Mumps---damage to BM seminiferous tubules—immune response---Orchitis 27
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Cross reacting foreign Ag Similary b/w some foreign & Self Ag Indivisual Nerve tissue damage-antirabies immunization of human with neural vaccine of infected sheep brain Streptococcal M protein—heart ms—Heart damage Nephritogenic strain streptococcus-- GN 28
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Molecular mimicry Identical peptide sequence in epitopes b/w microorganism & Self Ag HLA B27- Arthritogenic strain of S. flexneri Joint membrane- M. tuberculoisis Myocardium- Coxsackie B virus 29
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Polyclonal activation of B cell Ag--- corresponding B cell activation Polyclonal activation of B cells: Chemical (2 ME) Bacterial product (PPD, LPS) Enz (Trypsin) Antibotics (Nystatin) Infection (Mycoplasma, EBV, Malaria) 31
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Forbidden clones Breakdown of immunological homeostasis lead to cessation of tolerance & emergence of forbidden clones of immunocompetent cell----immune response against self Ag Injection of Self Ag with Freunds’s adjuvant 32
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Altered T or B cell function Enhanced Helper T cell ↓↓ Suppressor T cell function Defect in thymus Stem cell development Macrophage function Idiotype-antiidiotype network defect 33
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Hemocytolytic autoimmune Ds Autoimmune Hemolytic anaemia Cold autoAb—IgM Ab—agglutinate RBC at 40C Following syphilis, 10atyptical pneumonia, Malaria, Trypanosomiasis Warm AutoAb-IgG Ab-Non agglutinating Drugs-sulphonamide, antibiotics, alpha methyldopa RBC coated with Ab—destroyed in spleen 40
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Hemocytolytic autoimmune Ds Autoimmune Thrombocytopenia—ITP Autoimmune Leucopenia- Non agglutinating Antileucocyte Ab serum of patient with SLE, RA 41
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Localised Organ Specific Ds 42
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SLE Biological False +ve STS Variety of AutoAb Nuclei Intracytoplasmic cell constituents Thyroid & other organs LE cell- Neutrophils containing LE Bodies (large pale homogenous body) almost filling cytoplasm Antinuclear Ab (ANA)—Sensitive but not specific Pattern: homogenous, Peripheral, speckled, nucleolar Anti DNA Ab- ds, ss, both Anti-ds DNA Ab & Anti sm Ab---specific for SLE 47
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THANK YOU 60