|(T/F) an antigen encountered in the gut will cause IgA to be released in the saliva against that antigen.||True|
|Intraepithelial Lymphocytes (IELs)|| lymphocytes found in the epithelium. They exclude the MΦ and dendritic cells.|
» Exclusively T-cells expressing CD3 (CD3⁺)
» Most (85-95%) are CD8⁺ (cytotoxic/suppressor)
» Higher proportion of the γ/δ TCR.
|Mucosa Associated lymphoid tissue (MALT)|| D-MALT - Diffuse MALT |
O-MALT - Organized MALT
|GALT||Gut associated lymphoid tissue|
|BALT||Bronchus associated lymphoid tissue|
|(T/F) <i>Monomeric</i> IgA is produced by plasma cells of lymph nodes.|| True|
Plasma cells of <b>lamina propria</b> only produce polygenic IgA.
|The ___________ is where most of the secretory IgA (SIgA) is produced.||lamina propria|
|(T/F) the epithelial cells of mucous membranes also express class II MHC molecules and may participate in antigen presentation.|| True|
These are the same epithelial cells that participate in the secretion of IgA into the lumen. the process is called <b>transcytosis</b>
|Transcytosis|| a process in which endothelial cells pick up droplets of fluid on one side of the plasma membrane by pinocytosis, transport the vesicles across the the cell, and discharge the fluid on the other side by exocytosis. This is done by epithelial cells. |
PlgA → SlgA
|The <i>immune</i> cells scattered within the epithelial layer as well as the lamina propria constitute the:||Diffuse mucosa associated lymphoid tissue or D-MALT|
|What is the central feature of O-MALT?|| » lymphoid follicle within a germinal center. |
» No capsule surrounding it
» from outside → inside; germinal center, the follicle proper, a para-follicular region and a dome region.
e.g. peyer's patches, tonsils
|The __________ is the area between the follicle proper and the epithelium.|| |
Dome region or corona
|What is the main Ab expressed by B-cells in the parafollicular regions and the corona region?|| |
IgM surface isotype
* In the germinal layer most B cells swithced to IgA isotype
| _______ cells are found in corona, whereas ______ cells are more abundant in the parafollicular regions.|
a. CD4⁺ T
b. CD8⁺ T
CD4⁺ T cells are found in corona, where as CD8⁺ T cells are more abundant in the parafollicular regions.
|Follicle-associated-epithelium of FAE|| |
the epithelium overlying the follicle
This is where you can find the <b>M cells</b>.
|M cells|| » found in the Follicle-Associated-Epithelium (10% of FAE)|
» they have small folds on the luminal surface
» Express HLA-D molecules
» Basal Beside has a pocket, dendritic cells, MΦ, T-cells,
» <u>Function</u>-<i> antigen transport from lumen to the antigen presenting cells (APCs) on the basal surface. (do not process Ag)</i>
| Which of the following is not found in the epithelium layer of the tonsils?|
a. M cells
b. Memory cells
c. Langerhan's cells
| a. M cells|
b. Memory cells ✓ → found in the mantle zone which is the underlying layer to epithelium.
c. Langerhan's cells
|Between the mantle zone of adjacent follicles is the _____________.|| extrafollicular zone. |
This is where antigen is presented to T cells.
|In which part of the tonsils, the Ag is presented to the T-cells?||in the extrafollicular zone|
|B cells constitude ___% of the total lymphocyte population in the palatine tonsil and are found in mantle zone as well as in the crypt epithelium.|| 52%|
Only 2% of the total cells in the palatine or nasopharyngeal tonsils are plasma cells.
|(T/F) Antigen is endocytosed by M cells or by FAE.||true|
|(T/F) The B cells in the peyer's patch are signaled to produced IgA by antigen.|| False|
Antigen signals the cells to swtich isotype but not to secrete it yet.
|After cells are activated in the peyer's patch, where do they go?||they leave the peyer's patch and migrate to the mesenteric <b>lymph nodes</b>, where they <u>proliferate</u>. → enter the systemic circulation → migrate back to the original mucosa. (in this case, lamina propria of the gut)|
|Most of the B cells of the lamina propria are commited to production of which antibody?||IgA|
|(T/F) Many of the cells in the germinal centers are found to contain IgA and J chain, but little Secretory IgA (SIgA) is released by the tonsil.|| T|
It releases more IgA than lymph nodes, but still most of the immunolgobulin released by the tonsil is IgG.
|most of the immunoglobulin released by the tonsils is:||IgG|
|Most of the SIgA in the oral cavity is released by:||major and minor salivary glands.|
|describe the monomeric IgA structure|| » 2 heavy chains and 2 light chains|
» NO J chain
» Secreted by plasma cells in bone marrow
| which one is the major form in the blood and is secreted by B cells or plasma cells in the bone marrow?|
|structure of pIgA|| » Usually but not always a dimer|
» in its dimeric form it consists of 4 heavy chains, 4 light chains and a <b>J chain. </b>
|(T/F) pIgA can only be produced in the producing cell. not in the extra cellular fasion.||true|
| Which is the minor form in the blood?|
|SIgA||» Secretory IgA|
» 4 light, 4 heavy + J + S component (5 pieces)*
* binds to the J chain and is the remnants of the polyimmunoglobulin (pIg) receptor which is expressed on the basal side of the epithelial cell. During transcytosis, the receptor is cleaved, leaving the secretory component with the pIgA molecule. the secretory component RETARDS degredation by protease.
| Which one of this has interference with microbial adhesion as their primary function?|
| a. IgA|
c. SIgA ✓
SIgA also facilitate microbial killing by activating lysozyme in an indirect way. both SIgA and lysozyme bind to mucin and therefore if a bacteria bind to SIgA, it will be more susceptible to lysozome because it is also bound to mucin.
|Explain how SIgA facilitate microbial killing||SIgA also facilitate microbial killing by activating lysozyme in an indirect way. both SIgA and lysozyme bind to mucin and therefore if a bacteria bind to SIgA, it will be more susceptible to lysozome because it is also bound to mucin.|
|(T/F) SIgA is very good at neutralizing toxins and viruses.||True|
| Im most people secretion of which isotype dominates?|
| b. IgA1|
however, in the oral cavity, the ratios are nearly equal
|how do some pathogengs such as <i>Streptococcus pneumoniae, Haemophilus influenzae</i>, defend themselves against SIgA1?||They release protease that destroys SIgA1 but not SIgA2|
|Mucin||high molecular weight proteoglycan which <i>traps bacteria and other substances (protein and carbohydrates) non-specifically</i>. ★ It helps blocks microbial adherence.|
|Lactoferrin|| one of the protective components of Saliva which|
1. sequesters Iron from microbes.
2. inhibit the oxidative degredation of mucin.
|Lysozyme||is a muramidase which degrades the cell wall of bacteria.|
|Lactoperoxidase||generates toxic compounds such as hypothiocyante which is toxic to bacteria.|
| The ratio of B cells to T cells in the gingival crevicular fluid is _______ than that seen in blood. |
|What is the major route of entery for leukocytes in the oral cavity?||through GCF|
| which of the following is not present in GCF?|
|they are all present in the GCF but at lower concentrations than serum.|
| What is the major route of entery for IgG and IgM into the saliva?|
a. salivary secretion
| b. GCF|
concentration in saliva ↑ by gingival inflmmation.
|Which component of complement system is found in the GCF?||C3|