Immunological functions of the alimentary tract Flashcards
What are the Divisions of the immune system?
Innate and adaptive
What is innate immunity?
Prevents infections and avoids disease
Non-specific
No memory
Mediated by:
- macrophages
- epithelial barriers
- secretions
What is adaptive immunity?
Responds to infections and prevents disease
Highly specific; response to targeted microbe
Memory (B and T memory cells)
Mediated by:
- lymphocytes
- antibodies
Describe the systematic immune response.
Protects the entire body
- Bone marrow
- Spleen
- Thymus
- Lymph system
- Blood circulation
Describe the mucosal immune system.
The immune system that protects internal mucosal surfaces:
- oral surface
- nasal surface
- lacrimal surface
- GI tract
- Bronchial tract
- Genitourinary tract
- Mammary glands
which are the site of entry for virtually all pathogens and other antigens.
What is the Role of secretions at mucosal membranes?
Function to wash away anything that is there
*meaning pathogenic bacteria must try to adhere to these surfaces and not be washed away
What are the Innate mechanisms of mucosal protection?
- Mucin
- Peristalsis
- Antimicrobial peptides and proteins e.g. lysozyme, lactoferrin, phagocytes
What are Adaptive mechanisms of mucosal protection mediated by?
mediated by antibodies (mucosal/secretory immune system)
- IgA/IgM
- IgG
Describe the Sources of Serum, Saliva and Local Antibodies in the Oral Cavity.
-Saliva can protect the tooth. Contains enzymes and antibodies and we push that through into our mouths the whole time
-The gingival tissues constantly have a serum exudate going on to the tooth surface
o The exudate is derived from the blood system
- The exudate contains all the blood components apart from RBCs
- It has WBCs, antibodies and lymphocytes
Give the Three primary routes of infection for a pathogen.
1) Breach of the epithelium
- e.g. a stomach ulcer
2) Squeezing across epithelial junctions
- passively or via Langerhan cells which will carry the pathogen across
3) Peyer’s Patches
- collection of WBCs in the gut, which is the lymph node of the mucosal immune system and samples what is in the gut lumen through a specialised M cell, with the rest of the Peyer’s patch covered by normal columnar epithelium
Name 3 lymphoid cells.
Intra-epithelial lymphocytes
Lymphocytes and macrophages scattered in the lamina propria
Peyer’s patches
What is the M cell?
Sits on top of the Peyer’s patch and samples the gut fluid lumen and sends it down to the lymphocyte underneath
*easiest point of entry for pathogens
Describe the Migration of Immune cells from Peyer’s Patches.
Once a pathogen gets through to the lymphocytes, it triggers an immune response. A B-lymphocyte will start to mature into a B-cell, as it does this it will migrate away from the Peyer’s patch and drain to the local lymph node (mesenteric lymph node-where they continue to mature) and enter back into the lymph circulation back into the blood circulation.
Describe the process of the Common Mucosal Immune System.
- The WBC picks up the antigen and the WBC matures
o The WBC travels through the lymph drainage to the mesenteric lymph node
o It continues its maturation and it travels up through the lymph drainage and gets released into the blood stream
o It travels through the blood stream, goes back to the gut to provide antibodies
♣ However, it also goes to everywhere else in the mucosal immune system
The most interesting thing about a common mucosal immune system is that if you introduce a vaccine to a Peyer’s patch in the gut, you don’t only get a response in the gut, but also in your saliva, breast milk, lacrimal fluid etc.
*encountering an antigen at one mucosal site leads to immunity across all mucosal sites
What are Mucosal antibodies?
Predominantly SIgA (secretory IgA)
Found in all secretions and breast milk
Provides passive immune protection in new-born infants
