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Food related allergies and intolerances Immunology
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Lecture notes of all the lectures of the immunology part with extra information/notes
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Lectures Food Related Allergies and Intolerances30-10-2023
Lecture basics and early life immunology
8 most common allergens:
- Milk
- Egg
- Fish
- Peanuts
- Shellfish
- Tree nuts
- Soybeans
- Wheat
General concept
1. Hypersensitivity
a. Undesirable effect against foreign stimuli
b. Stimuli are usually tolerated/nonharmful
2. Allergy
a. Immune mediated hypersensitivity
b. Intact immune system
3. Intolerance (non-allergy)
a. Non-immune mediated hypersensitivity
b. Lactose intolerance (enzyme deficiency)
4. Hyperreactivity (non-allergy, not immune system that
reacts on it)
a. Excessive irritability
b. Physical stimuli: smoke, dust, perfume, cold air
The players in immunity to infection and allergy
The good…
- Innate immune cells (aangeboren afweercellen):
o Macrofages
o Granulocytes
o Mast cells
o NK cells
o Dendritic cells
- Adaptive immune cells (aangeleerde afweercellen)
o Lymfocytes
o T cells
o B cells
The good, bad and ugly
- Bacteria
- viruses
- Parasites
- Allergens
,Anatomy of the systemic and mucosal immune system
1. NALT (Nasopharynx-associated lymphoid tissue) → Represents immune
system of nasal mucosa (=a type of tissue that lines the nasal cavity) and is
a part of mucosa-associated lymphoid tissue (MALT)
2. BALT (Bronchus-associated lymphoid tissue) → cells of BALT protect the
bronchial regions of the lower respiratory tract
3. GALT → GALT cells defend the lining of the gut
4. GERALT
Hematopoiesis
= formation of blood cellular components
Function of the immune system: discriminate between SELF and
NON-SELF
- Non-self = infection, bacteria, viruses
- Modified Self = tumour (produced in the body by own cells)
The immune system should react on non-self organisms and protect the body
Lymphoid organs
- Remove foreign material in lymph, are lookouts in immune system
o Lymphoid tissue
▪ Common in gastrointestinal tract and respiratory tract
o Lymph nodes
▪ Balls of lymphoid cells and proteins
▪ Found in neck, armpit and in the intestinal walls (peyers patches)
Dendritic cells detect an antigen or other external component → in the lymph nodes the dendritic
cells present the antigen to the B-cells that come across → B cells are a type of lymphocyte that
produce antibodies
Circulating T-cells → move between the lymph nodes and blood on the lookout for pathogens and
infected/ abnormal cells that are tagged with antibodies
What is immunity?
- A well balanced immune response to threats such as infection and allergy
- Excessive immune responses lead to allergy and inflammation (relevant for all age related
non-communicable diseases)
- Inadequate immune response lead to infections
- Immunity can be influenced by diet, microbiota, age, genetic make-up and environmental
exposures
A balanced immune response is a crucial for immune health
- Inadequate immune response (not work good enough)
o Cancer
o Infection
o Immunodeficiency
- Excessive immune response (works to much)
o Autoimmunity
, o Allergy
o Inflammation
Genetic, diet, microbiota, environment → can influence the balance (immune regulation)
Interaction between the innate and adaptive immunce cells
- Macrophages, DC, Monocytes, NK cells, Neutrophiles, Eos
o Immediate response
o No immune memory (second time same response)
o Limited specificity
o PRR (pattern recognition receptors)
- B and T cells
o Delayed response
o Immune memory
o High specificity → very specific receptor
▪ Immunoglobulins
▪ T cell receptors
Timing of immune responses: innate vs adaptive
When you are infected (first time) by a virus the phagocytes are activated (in the first 2 days)
The T-cells has a slower activation (the first time of infection)
Antibodies are only produced 6 days after infection
Pathogens are recognized by the innate immune system using pattern recognition receptors (PRR),
most notably the Toll like receptors (TLR)
➔ When a pathogen reaches the physical barrier the innate immune system provides an
immediate but non specific response
o The response is most of the time triggered by microbes which are identified by
pattern recognition receptors (PRR)
▪ PRR’s are sensor machines which can detect molecules typical for pathogens,
they detect specific parts of a bacteria/parasite/virus
- Membrane, bound Toll like receptors
o Gram positive bacteria → TLR1, TLR2:TLR6, TLR3
o Gram negative bacteria → TLR4
o All flagellated bacteria → TLR5
- Intracellular Toll like receptor → recognise viruses and other intracellular pathogens
- Other types of PRR:
o RLR
o NLR
o CLR
, Function of CD4 and CD8 T-cells in clearance of pathogens
- Helper T cells (CD4) = recognizes complex of antigenic peptide with MHC class II and
activates B cell
- Cytotoxic T cell (CD8) = recognises complex of viral peptide with MHC class I and kills infected
cells
Antigen uptake and processing, and presentation
1. Binding
2. Uptake
3. Processing and presentation
MHC-restricted recognition of peptide by TCR
T-cell subsets
There are different T-cells → they are different in the way they are activated and when they become
activated they produce different cytokines
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