Transcript
ASSESSMENT
• Continuous assessment:• Quizzes 10%• Mid Semester Exam 30%• Final Semester Exam 60%
Team Teaching
• Prof Dr Zauyah Yusuf• Madam Mahani Mahadi• Madam Shamima Abdul Rahman
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Synopsis Basic immunology includes topics and themes
considered essential for basic understanding of immune system. It covers the structure, organization and function of the immune system together with the mechanism of normal immune response. The immunopathology of diseases caused by an abnormal immune response and the basis of immunological tests used in the diagnosis of certain diseases are also introduced.
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References• Mark P, Diego V. 2009. Basic and Clinical Immunology.
Second Edition. Elsevier Churchill Livingstone.• Roderick N and Matthew H. 2004. Immunology for
Medical Students. Elsevier Mosby. • Stites DP, Terr Al and Parslow TG. 2001. Medical
Immunology. 10th Edition, Appleton & Lange, Prentice-hall International Inc.
• http://www.microbiologybytes.com/iandi/2b.html• http://www.wellesley.edu/Biology/Concepts/Html/ant
ibody.html• http://faculty.ccbcmd.edu/courses/bio141/lecguide/u
nit5/index.html#abystructure
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Introduction to Immune System
Pn Mahani Mahadi
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Learning Outcomes:
• At the end of this lecture, student should be able to :
• Identify and differentiate cells of immune system
• Identify tissues of immune system • Explain roles of each cells and tissues
of immune system.
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What is immunology?
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• Immunity or latin words immunis mean ‘free from burden’ or defined as a resistance to disease caused any microorganism.
• Immune system is a collection of cells, tissues and molecules that mediate resistance to infections.
• Immunology is the study of the immune system and its responses to invading pathogens.
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Role of The Immune System:1.Defense against infections2.Recognizes and responses to tissue
grafts and newly introduced proteins3.Defense against tumors4.Produce antibodies ( highly specific
reagents for detecting any class of molecules)
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Types of Immunity
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Cells of Immune System
• Bone marrow is the source of the precursor cell that give rise to the cellular constituent of immune system.
• Production of immune cells or all blood cells lineage is known as haemopoiesis process.
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• Immunology concentrates upon the roles of white blood cells in host defense included granulocytes :
• (neutrophils, eosinophils and basophils), monocytes and dendritic cells and lymphocytes.
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Monocytes•When they enter extravascular pool and become resident in the tissues known as macrophages MQ (mature form of monocytes)•They are larger than neutrophil and lymphocytes, have a single nucleus and abundant granular cytoplasm.•Special MQ exists in different tissues- Kupffer cells (liver), mesangial cells (kidney), microglial cells (brain) and osteoclast (bone). •Dendritic cells -> very small population , derived from bone marrow and specialized function in activation and priming of lymphocytes.
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Lymphocytes•B lymphocytes differentiate in bone marrow b4 released into the circulation. Role as recognition of macromolecules (antigen) thro surface receptors (antibody).•May mature into plasma cells remain fixed in the tissues and acts as secretors of soluble antibody.•T lymphocytes derived from thymus, pivotal cell in immune response, able to recognize and destroy infectious agents and foreign tissues.
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Tissues and Organ of Immune System
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• The tissues of immune system consist of the generative ( primary) lymphoid organs in which B and T lymphocytes mature and become competent and peripheral (secondary) lymphoid organs which adaptive immune response are initiated.
• Primary lymphoid organs composed of thymus and bone marrow. Sites of development and maturation of immune response cells.
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Tissues and Organ of Immune System
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MALT
GALT
• The bone marrow and the thymus constitute the primary lymphoid organs.
• Both B-lymphocytes and T-lymphocytes are produced from stem cells in the bone marrow. B-lymphocytes mature in the bone marrow while T-lymphocytes migrate to the thymus and mature there.
• After maturation, both B-lymphocytes and T-lymphocytes circulate through and accumulate in secondary lymphoid organs.
1) Bone Marrow:• All immune cells derived from stem cell in the
bone marrow.• Site of origin of red blood cells, white blood
cells (immune cells) and platelet.
2) Thymus: • Lymphoid cells undergo a process of
maturation and education prior to release into the circulation.
• allows T cells to develop the important attribute known as self tolerance.
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Primary and Secondary Lymphoid organs
Thymus• grows rapidly during first year,
then stays same size through adulthood. Decreases in size after 60 years.
• No reticular fibers: internal network formed by epithelial cells with long processes.
• Cortex (numerous lymphocytes) and medulla (fewer lymphocytes)
• Site of maturation of T cells: many T cells produced here, but most degenerate. Those that remain can react to foreign substances, but not to healthy body tissue.
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• Secondary lymphoid organs.a)Which consist of the lymph nodes, the spleen,
mucosa-associated (MALT) and gut-associated (GALT) lymphoid tissue.
b)Have 3 major functions: 1.residence of variety of lymphoid cells, 2.traps for antigen, 3.anatomical site in which immune responses are
initiated.
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Lymph Nodes• Superficial (near skin) and deep.• Organized into cortex and medulla
with dense connective tissue capsule surrounding. Trabeculae extend within. Reticular fibers form supporting network.
• Only structures to filter lymph• Afferent and efferent vessels• Substances removed by
phagocytosis or stimulate lymphocytes to proliferate in germinal centers.
• Cancer cells often migrate to lymph nodes, are trapped there, and proliferate. Can move from lymphatic system to circulatory system spreading cancer through body.
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3 Regions of Lymph Nodes
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2) Spleen• act as part of the immune system and as a filter. • located in the upper left quadrant of the
abdomen.• two distinct components of the spleen, the red
pulp and the white pulp.Red pulp: consists of large numbers of sinuses and
sinusoids filled with blood1)is responsible for the filtration function of the
spleen. 2)facilitate removal of old or damaged red blood
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White pulp consists of aggregates of lymphoid tissue and is responsible for the immunological function of the spleen
• contains T cells, B cells and accessory cells• purpose is to mount an immunological response to
antigens within the blood.• Surrounds the splenic arteries, forming a
periarteriolar lymphoid sheath (PALS) populated mainly by T lymphocytes.
• Clusters of B lymphocytes in the White Pulp form primary follicles occupying a more peripheral position.
• Upon antigenic challenge, these primary follicles develop into characteristic secondary follicles containing germinal centers.
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Functions of the SpleenThe immune functions include:
proliferation of lymphocytes production of humoral antibodies removal of macromolecular antigens from the
blood
The hematopoietic functions include:formation of blood cells in fetal life removal and destruction of senile, damaged
and abnormal RBCs and platelets retrieval of the iron from hemoglobin
Spleen
Spleen
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• lymphoid tissue is also found at other sites, mostly in the gastrointestinal tract, respiratory tract (tonsillar, naso-pharyngeal, bronchial) and urogenital tract.
• Peyer patches large aggregates of lymphoid tissue found in the small intestine.
• facilitate the generation of an immune response within the mucosa. Function similar to bone marrow.
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Gut-Associated (GALT) Lymphoid Tissue
Mucosa-Associated (MALT) Lymphoid Tissue.
Lymphocyte Recirculation.• Total number of lymphocytes in a healthy
adult is about 1012 of which 0.1% are renewed daily.
• They do not reside in any single organ• They re-circulate between the blood, tissues
and lymphoid organ. • Complete cycle of circulation in 1-2 days.• It is a process of immune surveillance and
controlled according to cell type and anatomy.
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• Circulation - virgin lymphocytes move from the primary to secondary lymphoid tissue via the blood activated lymphocytes move from the spleen, lymph nodes and MALT into the blood and
• hence to other lymphoid and non-lymphoid tissues antigen presenting cells such as macrophages and dendritic cells may carry antigen back to lymphoid tissues from the periphery.
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Overview of the Lymphatic
System
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Thank You
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