1. Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – 422222, India

2. OC-SBT052-U01-04 Introduction Programmes and Courses  SEP – SBT052 – Unit 01

3. 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 arunmesh@hotmail.com

4. 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 40-60 minutes during Face-To-Face counseling.  Discussion about students difficulties or tutorial with assignments should follow the lecture for about 40-60 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.

5. 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 development of suppressor T cells. Describe development of Dendritic cells. Describe roles of Suppressor and Describe Dendritic cells in immunological responses.

6. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.6 Introduction  This presentation is about Dendritic cells. Suppressor cells B-Lymphocytes Functions of each of them Activation of B lymphocytes Interaction of APC and B lymphocytes.

7. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.7 Cells of Immune System  Suppressor T Lymphocytes  They possess CD8 surface antigens.  Suppressor T Cells control the proliferation of T cytotoxic and T-helper Cells.  Activity of suppressor cells is controlled by T T regulatory cells(cd4+cd25+ ).  CD4+CD25+ regulatory cells prevent activation of T cells and production of IL-2.  CD4+CD25+ cells recognize self antigens and they express Foxp3 antigens.  Foxp3 convert naive Cd4+ T cells into TR (T regulatory cells i.e. CD4+CD25+ cells).

8. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.8 Dendritic Cells-1  They are macrophages type immature cells in peripheral tissues.  Dendritic cells possess several receptors such as mannose receptors, receptors for complements, scavenger receptors, Toll like signaling receptor(TLR-4) and class II MHC molecules.  TLR-4 receptor recognizes LPS of Gram positive bacteria.  They are capable of acquiring and activating T- Lymphocytes after present the foreign antigens to them.

9. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.9 Dendritic Cells-2  Antigenic stimulation to Dendritic cells lead to Expression of more MHC class II and B7 molecules on their cells surface.  Such activated cells then travel to regional lymph nodes to interact with other immune cells.  They are most active and effective antigen presenting cells.  Dendritic cells can take up wide varieties of antigens.  They are long lived and possess mitochondria.

10. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.10 Dendritic Cells-3  Four types of Dendritic Cells are as follow.  Myeloid dendritic cells  Langerhans cells  Interstitial dendritic cells and  Follicular dendritic cells.  Myeloid, Langerhans and Interstitial type of dendritic cells arise in bone marrow  Except follicular dendritic cells, all type of dendritic cells share same characteristic features

11. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.11 Dendritic Cells-4  Follicular Dendritic Cells They do not arise in bone marrow These cells do not possess MHC class II molecules on their surfaces. They reside in lymph follicles and Possess numerous receptors for antibodies,  because of which they can clear antigen-antibody complexes from tissues.

12. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.12 Cells of Immune System-1  B-Lymphocytes  They developed and mature in bone marrow and acquire their characteristic Ig surface markers.  They lack the receptors for the sheep's R.B.C.  They are usually arrange in the white pulp of spleen and cortex region of lymph nodes.  Their main immunological function is to carry out antibody production.  B cells possess B Cell Receptor(BCR) which is divalent in nature which are unique for their corresponding antigenic determinant.

13. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.13 Cells of Immune System-2  Maturation of B Lymphocytes Maturation of B lymphocytes occurs in bone marrow. Maturation of B lymphocytes is stimulated by Interleukin-7 produced by stromal cells of bone marrow. In maturation of B cells, there is generation of large proportion of functional B cells antigen receptors on these cells. In bone marrow, then there is selection of only those B lymphocytes which come to possess the functional antigen receptors molecules on their surfaces.

14. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.14 Cells of Immune System-3  On B cells, B cell receptors are associated with Ig- alpha and Ig-beta complex.  B cells posses IgG, IgM and IgD molecules embedded into their membrane and act as surface receptors for foreign antigen.  On activation B cells loose its IgD receptors.  B cells also act as antigen presenting cells.  B cells exhibit two types of mechanism of their activation to mount immune responses:  T cells dependent immune response.  T cells independent immune response.

15. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.15 Cells of Immune System-4  Activation of B cells by T-cells-dependent and T-cell- independent antigens:-

16. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.16 Cells of Immune System-5  Activation of B cells by Th2 lymphocytes

17. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.17 Cells of Immune System-6  T cells Dependent Immune Response T cells dependent immune response  In T cells dependent immune response, antigen bind to IgM receptor and engulfed processed and presented to T lymphocytes.  Activated T cells secrete cytokines which activate cells division and its differentiation into antibody secreting plasma cells.  The antigen which activate the B cells via intervention of T lymphocytes are called as T cells dependent antigen.  The binding of CD40 receptors with its ligand on the T cells result into the class switching to IgM to IgG producing B cells and production of memory B cells.

18. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.18 Cells of Immune System-7  T Cells Independent Immune Response T cells independent immune response,  In T cells independent immune response, B cells get directly activated to secrete IgM antibodies.  The antigens which activate the B cells to mount such T cells independent immune response are called as T cells independent antigens.  T-cells independent antigens possess numerous epitopes which are mainly polysaccharide in nature and can bind multiple B cell receptors activating the B cells directly without the help of T lymphocytes.  However since there is no involvement of T cells in the activation of B cells, immunoglobulin class switching do not occur and therefore the B activated by T cells independent antigens produce only IgM antibodies and there is no generation of B cell memory cells.

19. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.19 What We Learn…..  Development of B cells, suppressor cells and dendritic cells.  Immunological roles of each of these cells.  What are the mechanism of maturation and selection of B cells.  Activation of B cells.  Interaction between APC and B lymphocytes.

20. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.20 Critical Thinking Questions  Why B cells mount fast immune response to T- independent antigens?

21. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.21 Tips for Critical Thinking Questions  Differences in the mechanisms of mounting immune responses to T-dependent and T-independent antigen.

22. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.22 Study Tips  Book Title:Roitt’s Essential Immunology, 10 th ed. Title:Roitt’s Essential Immunology, 10 th ed. Author: Roitt I.M. Publication: Publication: Blackwell Science 2001.  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; 357:1777-1789.

23. End of the Presentation Thank You !