Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – , India

OC-SBT052-U01-05 Introduction Programmes and Courses  SEP – SBT052 – Unit 01

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.3 Credits  Academic Inputs by Arun Punaji More. M.Sc. (Microbiology) Experience: 11 Years

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.4 How to Use This Resource  Counselor at each study center should use this presentation to deliver lecture of minutes during Face-To-Face counseling.  Discussion about students difficulties or tutorial with assignments should follow the lecture for about minutes.  Handouts (with 6 slides on each A4 size page) of this presentation should be provided to each student.  Each student should discuss on the discussion forum all the terms which could not be understood. This will improve his writing skills and enhance knowledge level about topics, which shall be immensely useful for end exam.  Appear several times, for all the Self-Tests, available for this course.  Student can use handouts for last minutes preparation just before end exam.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.5 Learning Objectives  After studying this module, you should be able to: Describe the Roles of Natural Killer cells in immunological responses and Describe the roles of cytotoxic cells in immunological responses.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.6 Introduction  This presentation is about Natural Killer cells and their immunological functions. Cytotoxic cells and their immunological functions Activation of Natural killer cells. Activation of cytotoxic cells.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.7 Natural Killer Cells-1  Unlike T and B cells, natural killer cells are large and granular.  They constitute 5% to 10% of the total lymphocytes population in the peripheral blood.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.8 Natural Killer (NK) Cells-2 NK cells mount non specific immune responses against pathogen infected cells. They are filled with potent anti pathogen granules. NK cells nonspecifically kill virus infected cells and cancer cells and MHC –mismatched bone marrow graft. NK cells can directly lyse their target cells mentioned above. NK cells are early producer of INF-gamma.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.9 Natural Killer Cells-3  They recognize the target cells because of reduced density of MHC class I molecules on virus infected or cancer cells.  The another mechanism which NK cells employ to attack their target cells is by interaction between their CD16 receptors for carboxyl-terminal end of IgG molecules or Fc region of the IgG.  Thus if antibodies are produced against the changed receptors on the surface of virus infected cells or cancer cells and get reacted with such change antigens then NK cells recognize these changed Ag+Ab complex on surface and attach to such cells and kill them. (antibody dependent cell mediated cytotoxicity)

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.10 Natural Killer Cells-4 virus infected cells,cancer cells expressed very few MHC class-I molecules than the normal self cells; NK cells recognize the cells with such low molecule of MHC class-I and bring about their lysis after stimulation by cytokines. virus infected cells,cancer cells expressed very few MHC class-I molecules than the normal self cells; NK cells recognize the cells with such low molecule of MHC class-I and bring about their lysis after stimulation by cytokines. The NK cells get attached to the infected cells or cancer cells and ingest potent lethal chemical into such cells killing them. The NK cells get attached to the infected cells or cancer cells and ingest potent lethal chemical into such cells killing them. NK cells can also kill antibody coated target cells. NK cells can also kill antibody coated target cells.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.11 Natural Killer Cells-5 Functions of NK cells:

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.12 Cytotoxic T Lymphocytes-1 They recognize Ag+MHC class I molecules expressed on the infected cells and They destroy pathogen infected cells specifically by the process of apoptosis. These cells insert perforins into infected cells; cytoplasmic granules granzymes are then pump into the cytoplasm of the target cells, this activate caspase enzyme which induce DNA fragmentation and apoptosis.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.13 Cytotoxic T Lymphocytes-2 They expressed unique surface antigen known as CD8+. They are recognized as immune cells of adaptive immune responses. Cytotoxic lymphocytes kill virus infected cells. Cytotoxic cells are stimulated by the IL-2 secreted by Th1 ( T helper ) cells.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.14 What We Learn…..  Natural Killer cells.  Immunological functions of Natural killer cells.  The mechanism of killing infected or cancer cells by NK.  Cytotoxic cells.  Mechanism of mounting immune response by cytotoxic cells.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.15 Critical Thinking Questions  Why Natural killer cells are recognized as cells of Innate immune system?

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.16 Tips For Critical Thinking Questions  Mechanism of killing pathogen by Natural killer cells.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.17 Study Tips  Book Title:Cellular and Molecular Immunology Essential Immunology, 5 th ed. Title:Cellular and Molecular Immunology Essential Immunology, 5 th ed. Author: Abdul K. Abbas & Andrew H. Lichman. Publication: Publication: Elsevier Inc,  Journal Article Title:An Overview Of The Immune System. Title: An Overview Of The Immune System. Author:Parkin J, Cohen B. Author: Parkin J, Cohen B. Publication: Publication: Lancet 2001; 357:

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