Transcript PPT4 - Ycmou

Online Counseling Resource
YCMOU ELearning Drive…
School of Architecture, Science and Technology
Yashwantrao Chavan Maharashtra
Open University, Nashik – 422222, India
OC-SBT052-U01-04
Introduction
Programmes and Courses
 SEP – SBT052 – Unit 01
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Credits
 Academic Inputs by
 Arun Punaji More.
M.Sc. (Microbiology)
 Experience: 11 Years
 [email protected]
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How to Use This Resource
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Counselor at each study center should use this presentation to deliver
lecture of 40-60 minutes during Face-To-Face counseling.
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Discussion about students difficulties or tutorial with assignments should
follow the lecture for about 40-60 minutes.
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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.
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Appear several times, for all the Self-Tests, available for this course.
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Student can use handouts for last minutes preparation just before end
exam.
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Learning Objectives
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After studying this module, you should be able to:
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Describe development of suppressor T cells.
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Describe development of Dendritic cells.
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Describe roles of Suppressor and
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Describe Dendritic cells in immunological responses.
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Introduction
 This presentation is about
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Dendritic cells.
Suppressor cells
B-Lymphocytes
Functions of each of them
Activation of B lymphocytes
Interaction of APC and B lymphocytes.
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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).
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Dendritic Cells-1
 They are macrophages type immature cells in
peripheral tissues.
 Dendritic cells possess several receptors such as
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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 TLymphocytes after present the foreign antigens to
them.
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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.
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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
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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.
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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.
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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.
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Cells of Immune System-3
 On B cells, B cell receptors are associated with Igalpha 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.
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Cells of Immune System-4
 Activation of B cells by T-cells-dependent and T-cellindependent antigens:-
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Cells of Immune System-5
 Activation of
B cells by Th2
lymphocytes
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Cells of Immune System-6
 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.
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Cells of Immune System-7
 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.
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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.
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Critical Thinking Questions
 Why B cells mount fast immune response to Tindependent antigens?
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Tips for Critical Thinking Questions
 Differences in the mechanisms of mounting immune
responses to T-dependent and T-independent antigen.
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Study Tips
 Book
 Title: Roitt’s Essential Immunology, 10th ed.
 Author: Roitt I.M.
 Publication: Blackwell Science 2001.
 Journal Article
 Title: An Overview Of The Immune System.
 Author: Parkin J, Cohen B.
 Publication: Lancet 2001; 357:1777-1789.
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End of the Presentation
Thank You !