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Ins and Outs of Immunology

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Ins and Outs of Immunology Powered By Docstoc
					‫‪Introduction to Immunology‬‬
‫מבוא לאימונולוגיה והמטולוגיה‬ ‫יינתן ע"י ד"ר רמית מר )אימונולוגיה( וד"ר יהודית רדנאי‬ ‫)המטולוגיה(.‬ ‫ד"ר רמית מר – שעות קבלה: ימי ד' 03:51 – 03:81 )בנין 212 ק'‬ ‫ג'(‬ ‫ההרצאות באימונולוגיה כבר נמצאות בדף של ד"ר מר באינטרנט‬ ‫(‪.)ZIP‬‬ ‫הבחינה – שאלות ברירה בסריקה אוטומטית!‬ ‫לחייבים גם במעבדה: חובה לקבל ציון עובר במעבדה בקורס זה.‬ ‫קורס זה מהווה דרישת קבלה לקורסים באימונולוגיה ובהמטולוגיה‬ ‫בשנה ג'.‬ ‫עקב הביקוש הגדול מומלץ להירשם ברישום מוקדם; באימונולוגיה,‬

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Introduction to Immunology - Lecture 1:
• A bit of History. • Review of basic definitions. • Fundamental questions in immunology. • Recommended sources:

– Janeway & Travers “Immunobiology” – Roitt “Essential Immunology” – Open University course: ‫תורת החיסון‬

– http://www.ultranet.com/~jkimball/BiologyPages – http://rheumb.bham.ac.uk/teaching/immunology/index.html – http://gsbs.utmb.edu/microbook/ch050.htm

Protection from Pathogens
• Pathogens (= harm-causing agents) constantly attack all organisms. • Organisms have many Non-specific protection mechanisms:
– Skin (mechanical blocking, peeling). – Epithelial cell lining of all tracts open to external environment (e.g. digestive, respiratory, reproductive). – Body fluids: continuous washing, hydrolytic enzymes. – Phagocytic white blood cells.

• Existence of specific immunity has been known since antiquity. • Jenner (1749-1823): use of Vaccination. • Pasteur (1822-1895): proof that microorganisms cause disease; use of weakened microorganisms to immunize. • von Behring (1891): proof of existence of specific serum
antibodies (‫.)נוגדנים‬

The enemy: pathogens and antigens
• Antigens = activators of the immune response; include external pathogens, transplanted tissues, virally-infected or transformed body cells. • Immunogenicity = the ability to cause antibody production. • Antigenic determinant = epitope = the smallest structural unit that can react with the immune system. The response to each antigen is the sum of the reactions to all its epitopes. • Antigenicity (reactivity with immune system components) depends on the antigen’s difference from the self, its size (number of epitopes), and complexity (variability of epitopes).

What do we know about immune responses?
• The system responds to pathogens, but tolerates the self. • There are 2 types of immune responses:
– Primary: on first encounter with Ag. – Secondary: subsequent encounters with the same Ag: a much more rapid and efficient response (memory response).

• Learning & memory are specific: immunity to one disease is specific for that disease. • Stages of the immune response (10 & 20):
– – – – Recognition of the Ag. Decision whether to react, and if so, how. Action (effector function). Learning and memory.

HOW

DOES THE IMMUNE SYSTEM DO THIS?

How the immune system protects the organism against pathogens:
1 The immune system is a distributed system: Cells are created in the bonemarrow and thymus. Mature cells circulate in blood, tissues and lymph. Blood is filtered in the spleen, lymph - in lymph nodes.
Adenoids Tonsils Lymph Nodes

Thymus Spleen Peyer’s Patch on small intestine Appendix Lymphatic vessel Bone Marrow

How the immune system protects the organism against pathogens:
1 The immune system is a distributed system. 2 Immune cells survey the body for pathogens and signs of

damage:
Phagocytic cell

Going for the kill:

E. Coli bacterium

How the immune system protects the organism against pathogens:
1 The immune system is a distributed system. 2 Immune cells survey the body for pathogens & signs of damage. 3 Immune cells meet and interact in lymph nodes and spleen:

How the immune system protects the organism against pathogens:
1 2 3 4 The immune system is a distributed system. Immune cells survey the body for pathogens and signs of damage. Immune cells meet and interact in lymph nodes and spleen. Distributed decision-making: the immune response is the result of activities of all its cell population.

Main cell types of the immune system:
APC (antigen presenting cell) T CELL

CYTOKINES KILLER T CELL HELPER T CELL B CELL ANTIBODIES

The fundamental questions of immunology:
• How does the immune system recognize all antigens in the biological universe? • How does the immune system distinguish self from foreign antigens? • How is the proper mode of action for each pathogen chosen? • How are immune learning and memory achieved?

Immune recognition of all biological antigens:
• Each lymphocyte expresses a specific antigen receptor on its surface (membrane-bound receptors).

Immune recognition of all biological antigens:
• Each lymphocyte expresses a specific surface antigen receptor. • Receptor genes are rearranged from gene segment libraries:

Immune recognition of all biological antigens:
• Each lymphocyte expresses a specific surface antigen receptor. • Receptor genes are rearranged from gene segment libraries. • The result: Combinatorial diversity:
BCR-LC V genes D genes J genes 250 0 4 ~1011 BCR-HC 250-1000 12 4 V-D,D-J TCR 75 0 50 V-J ~1016 TCR 25 2 12 V-D,D-J TCR 7 0 2 V-J TCR 10 2 2 V-D,D-J ~1018

n-diversity TOTAL

• Further fine-tuning through mutation.

The fundamental questions of immunology:
• How does the immune system recognize all antigens in the biological universe? • How does the immune system distinguish self from foreign antigens? – Receptor diversity enables recognition of all proteins in the biological universe. – The system is too good! How does it avoid recognizing and reacting to self-proteins? – The answer is clonal selection: deletion of autoreactive B and T cells during their development.

T cell selection in the thymus

KIDNEY

THYMUS

The fundamental questions of immunology:
• How does the immune system recognize all antigens ...? • How does the immune system distinguish self from foreign...? • How does the system choose the proper mode of action for each pathogen? – Proper action depends on antigen type, quantity, site… – Decision is made on the level of cell populations, using Communication & Control: * Cell-cell contact interaction through membrane-bound molecules (adhesion molecules, co-receptors…). * Cytokines: messenger molecules.

The adaptive immune system at a glance:

The fundamental questions of immunology:
• How does the immune system recognize all antigens in the biological universe? • How does the immune system distinguish self from foreign antigens? • How does the system choose the proper mode of action for each pathogen? • How are immune learning and memory achieved? – Clonal selection of responding cells. – Some responding cells become memory cells. – In B cells: affinity maturation by hypermutation and selection.

Coming up next:
• • • • • Cells and tissues of the immune system. Recognition molecules in the immune system. Humoral and cellular immunity. Tolerance ( ‫ )סבילות‬and self-tolerance ( ‫.)סבילות עצמית‬ Primary and secondary immune responses; immune memory. • Communication and regulation in the immune system. • Immunological problems and diseases.


				
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posted:4/30/2008
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