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Esther Bokhobza estherbokhobza@gmail.

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Basic Immunology

BSc in Physiotherapy

Weeks 1-15Wednesdays 10-12

F.402

Immunitas = freedom from (Latin)

What is the function of the immune system?How does it recognize, eliminate and remember pathogenic

microorganisms?

How does it differentiate between harmful and harmless? How does it differentiate between self and non-self?

What about its specificity? What about flexibility? (Influenza)Speed? Is there room for failure? (Immunodeficiency)

Keep in mind!Harmful self- tumorsHarmless non-self- normal flora

Immunitas = freedom from (Latin)

We live in a potentially hostile world filled with infectious agents of diverse shape, size and composition which would

very happily use us as rich sanctuaries…

…had we not developed a series of defense mechanisms.

WHY IS THE IMMUNE SYSTEM SO IMPORTANT?

Viruses

Multicellular parazites (helminths)

Monocellular parazites

Virus

3 hours

3 hours

Bacteria

PATHOGENS

Cells of human body: 90% microbes, 10% human

Gut bacteria: 1014

Human cell population: 1013

DEFENCE MECHANISMS

Microbiological barriers

The normal floraA microbial community that inhabits the skin and mucosal membranes of mouth, gut and vagina. Symbiotic, non-pathogenic microbes, living in „peaceful” commensalisms.

In this ecosystem, the fittest survive and there is a competition over nutrients with pathogenic organisms. (Bacteria, Fungi, Protozoa, Viruses and Helminthes).

Physical and chemical barriers

pH of 3-4 Pepsin

Stomach

Skin

Tight junctions Keratin layer Antibacterial peptides; Defensins pH of 5.5 Fatty acids

Burns and susceptibility to infections!

pH of 3.8-4.5 Lactobacillus Lactic acid

Vagina

Eye Tear film (Oils, lactoferin, mucin and lyzosyme)

Respiratory tract

Impaired cilia movement (CF)!

Cilliary movement Coughing, sneezing

Primary lymphoid organs:

- Bone marrow- Thymus

Secondary lymphoid organs:

- Spleen- Lymphatic vessels- Lymph nodes- Adenoids and tonsils- MALT (Mucosal Associated Lymphoid Tissue) GALT (Gut Associated Lymphoid Tissue) BALT (Bronchus Associated Lymphoid Tissue) SALT (Skin Associated Lymphoid Tissue)

NALT (Nasal Associated Lymphoid Tissue)

LYMPHOID ORGANS!!

Bone marrow

Hematopoietic cells leave the central cavity and drain to a central vein

The bone marrow of a 65kg person weights 2.6kg and produces around 500 billion cells per day

Red bone marrow The site of hematopoiesis

Thymocytes

Epithelial cells

Dendritic cells

Macrophages

Thymus

Thymocytes from the bone marrow arrive at the thymus and mature into T cells

Spleen

Weights 150g, in the upper left abdomen. The

spleen filters the blood and serves as a secondary lymphoid organ

Spleen

Lymphocyte aggregations similar to the lymph node only that cells and pathogens enter from the blood

Red pulp- filters the blood; from antigens, microorganisms and worn-out RBCs

Lymphatic vessels

Lymphatic nodes

Lymph node

Secondary lymphatic tissues

Lymphatic tissues that are more diffused are generally known as MALT (Mucosa associated lymphatic tissue). Similar microanatomy as the lymph nodes and spleen

• Most of the pathogens get into human body through mucosa • A thin, huge surface, dinamic structure• Intense and active immune surveillance mechanisms ensure the

protection

• Mucus contains glycoproteins, proteoglycans, special enzymes• Anti microbial peptides provide biological defence mecanism

against intection• Most of the lymphocyte reside arround the mucosal surface

Secondary lymphatic tissues

MALT

Kripta

GALT

• The small intestine contains lymphoid nodules; the

Peyer’s patches and isolated lymphoid follicles.

• Pathogens are delivered across the mucosa to APCs by specialized mucosal epithelial cells are called the M cells (microfold cells).

• The Lamina propria contains lymphatic tissue underlying the gastrointestinal tract connective tissue

GALT

Intra-epithelial lymphocytes

GALT

• Antigens arising from Peyer’s patches and Lamina Propria travel to T cell areas in the GALT or Mesenteric lymph nodes.

• The large intestine contains isolated lymphoid follicles and the appendix

Guarding the gastrointestinal entrance

Waldeyer’s ring: Pharyngeal, Tubal, Palatine and Lingual Tonsils

Tonsilitis

NALT

Supplementary material

Edward Jenner 1796

The induction of immunity/protection from smallpox (cowpox)

FIRST VACCINATION

Louis Pasteur 1880

Immunization with attenuated pathogens against rabies

Ilya Mechnikov1883

Probiotics

Paul Ehrlich1900Phagocytosis

Pathogen recognition by special receptor, clonal proliferation to multiply cells that are able to

recognize the pathogen

Koch Laboratory, Germany 1890

Diphteria and Tetanus toxin

Emil Behring Shimbasaru Kitasato

1. Many diseases occur only once (natural protection)

2. Some diseases can be prevented by vaccination

3. The blood contains anti-bacterial activity (anti-toxins, serum therapy)

Protective humoral factors

Antibodies in serumbound to relevant pathogens