Basic Immunology
BSc in Physiotherapy
Weeks 1-15
Wednesdays 10-12
F.402
www.immunology.unideb.hu
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Password: download
Esther Bokhobza
estherbokhobza@gmail.com
Immunitas = freedom from (Latin)
What is the function of the immune system?
How does it recognize, eliminate and remember pathogenic
microorganisms?
Immunitas = freedom from (Latin)
How does it differentiate between harmful and harmless?
How does it differentiate between self and non-self?
Keep in mind!
Harmful self- tumors
Harmless non-self- normal flora
What about its specificity?
What about flexibility? (Influenza)
Speed?
Is there room for failure? (Immunodeficiency)
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?
Virus
PATHOGENS
3 hours
Bacteria
Viruses
3 hours
Multicellular parazites (helminths)
Monocellular parazites
Cells of human body: 90% microbes, 10% human
Gut bacteria: 1014
Human cell population: 1013
DEFENCE MECHANISMS
Microbiological barriers
The normal flora
A 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
Stomach
 pH of 3-4
 Pepsin
Skin





Tight junctions
Keratin layer
Antibacterial peptides; Defensins
pH of 5.5
Fatty acids
Burns and susceptibility to infections!
Eye
 Tear film (Oils, lactoferin, mucin and lyzosyme)
Vagina
 pH of 3.8-4.5
 Lactobacillus  Lactic acid
Respiratory tract
 Cilliary movement
 Coughing, sneezing
Impaired cilia movement (CF)!
!!
LYMPHOID ORGANS
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)
Bone marrow
Red bone marrow  The site of hematopoiesis
The bone marrow of a 65kg person weights 2.6kg and
produces around 500 billion cells per day
Hematopoietic cells leave the central cavity
and drain to a central vein
Thymus
Thymocytes from the bone marrow arrive at
the thymus and mature into T cells
Thymocytes
Epithelial cells
Dendritic cells
Macrophages
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
Secondary lymphatic tissues
MALT
 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
GALT
Kripta
GALT
• The Lamina propria contains lymphatic tissue
underlying the gastrointestinal tract connective tissue
• 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).
Intra-epithelial lymphocytes
GALT
• The large intestine contains isolated lymphoid
follicles and the appendix
• Antigens arising from Peyer’s patches and Lamina Propria travel to T cell areas in
the GALT or Mesenteric lymph nodes.
NALT
 Guarding the gastrointestinal entrance
  Waldeyer’s ring: Pharyngeal, Tubal, Palatine and Lingual Tonsils
Tonsilitis
Supplementary material
FIRST VACCINATION
Edward Jenner 1796
The induction of immunity/protection from smallpox (cowpox)
Louis Pasteur 1880
Immunization with attenuated pathogens against rabies
Ilya Mechnikov
1883
Probiotics
Phagocytosis
Paul Ehrlich
1900
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
Protective humoral
factors
Antibodies in serum
bound to relevant pathogens
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)