Exam II - Cutaneous & Mucosal Immune Flashcards
What components make up the mucosal immune system? Give specific examples.
Give specific examples. GALT (including peyers patches and tonsils), BALT, genitourinary tract, mammary gland, conjunctiva, salivary glands.
How does Ag reach the Peyer’s Patches?
Antigen transport to the Peyer’s Patches from the lumen is carried out by the M cells (microfold). Luminala antigens and micro-organisms are transcytosed into M cell pockets that contain T and B lymphocytes, FDC, and macrophages, and then to the organized mucosal lymphoid tissue under the epithelium.
(M cells ARE NOT APCs)
Where are M cells located?
They are located in inductive sites along the mucosa that lies over organized lymphoid follicles
Which isotype of Ab are produced in response to mucosal Ag primarily?
IgA
By which route do B cells activated in the mucosa reach the bloodstream?
They migrate via efferent lymphatics to the regional lymph nodes and thoracic duct into the bloodstream.
What form is sIgA found in? How are the units connected? Why is this form important?
sIgA is found in dimeric form, with a receptor polypeptide attached so that it is protected from the proteolytic enzymes in the lumen.
Which receptor does IgA bind to on the basolateral surfaces of mucosal epithelial cell?
pIgR (poly-Ig receptor, mucosal transport receptor)
What is the receptor peptide called after it is bound to IgA?
What is its function?
The secretory component
It functions to protect the IgA from proteolytic enzymes in the lumen.
Which are the innate immune components of the gi tract? What is the primary Ab produced there?
Low pH of the stomach, peristaltic movement, proteolytic enzymes, bile acids, pancreatic secretions, and normal flora. SIgA is the most abundant Ig produced there.
What substance lines the teat canal?
Keratin
How does keratin interact with bacteria?
Keratin binds 1x106 bacteria, and is also shed at milking which helps to prevent binding of bacteria to teat canal and flushing to remove it. It also contains dissolved fatty acids which is bactericidal.
Why should cattle be fed directly after milking?
In order to keep them standing for as long a period as possible, to give time for the teat canal to contract. (normally stays dilated for 2 hours after milking)
Explain the significance of the citrate/lactoferrin ratio
Lactoferrin and citrate both bind iron, though while bacteria can utilize citrate, they cannot use lactoferrin. Binding of iron to citrate competes with chelation of iron by lactoferrin, this a high molar ratio of citrate to lactoferrin enhances bacterial growth.
What is the consequence of having a low somatic cell count in the mammary gland?
A low somatic cell count predisposes the udder to infection by opportunistic pathogens.
Explain the roles of glycogen & lactobacillus in immune protection of the vagina.
Lactobacillus produces large quantities of lactic acid when utilizing the glycogen released during desquamation, which provides a more acidic environment for the vagina, preventing invasion.
