Lymphoid Functional Anatomy. The role of secondary lymphoid organs in trapping antigens For Tuesday Week 6 Practical Workshop, Dunnbook Chapter 10 Comments and Feedback please to the Author, firstname.lastname@example.org. Start/help. Left-click anywhere to continue.
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The role of secondary lymphoid organs in trapping antigens
For Tuesday Week 6 Practical Workshop, Dunnbook Chapter 10
Comments and Feedback please to the Author, email@example.com
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The lymphatics shown here are the superficial ones draining the skin. If all the lymphatics that drain organs were also shown, she would be green all over. Check that you know the difference between “lymphatic” and “lymphoid”. Why is it important to know the routes of lymphatics in cancer patients?
Here is a more detailed view in a child. Note the chains of nodes
Lymphatics and Lymphoid organs, overview
UnderarmLymph Node Chains in Three Body Regions
Try palpating an accessible node: see http://home.teleport.com/~bobh/Nodes.htm ) especially if you or your practical partner has an infection which has caused one to swell
Lymphnode chains in three regions
Compare scale with next slide
Here’s a chance to revise your knowledge of: Anterior, Posterior, Pre-, Supra-, Sub-….Surface Locations of Lymph Node Chainsin Head and Neck
A typical active lymph node, e.g. in an infection
Write a description of the immediate surroundings of the lymph node. The material in which it is embedded here is very typical.
Surface Locations of Lymph Node Chains
It’s pretty important for clinicians to get it right between lymph node enlargement due to an immune response, and to a tumour. That’s part of clinical training, but you could start thinking now how a scientific approach could assist in making the distinctionCancer: enlarged Lymph Node with lymphoma
Pathologists are fond of food metaphors for the very inedible specimens they study. Can you think of other examples?
Compare scale with previous slide
Cut sections of this enlarged lymph node involved with high-grade non-Hodgkin's lymphoma in AIDS reveal a "strawberry sundae" appearance with swirls and globs of red in white.
An enlarged lymphomatous lymph node
Sketch a stick-man schematic to make it clear from which view this X-ray was taken
This illustrates the connections between chains of lymph nodes by lymphatics
What might be the likely biological purpose of arranging lymph nodes in a series of chains like this?
Anything odd in this image?
The Black DeathNecrosis (gangrene) of the tissue caused by plaguefromhttp://www.historique.net/microbes/pestis.htmlPlague
If the history and current status of plague epidemiology interest you, see the recent WHO report
Fleas transfer the bacterial infection (Yersinia Pestis) from rodents by subcutaneous inoculation to various animals and topeople. Initial signs and symptoms may be nonspecific with fever, chills,malaise, myalgia (muscular pain or tenderness), nausea, prostration, sore throat and headache. Commonly a lymphadenitis (inflammation of the nodes) develops in those lymph nodes that drain the site ofthe flea bite, where there may be an initial lesion. This is bubonic plague,and it occurs more often in lymph nodes in the inguinal area and less commonly in the axillary and cervical areas. The involved nodes (“buboes”) become swollen, inflamed and tender and may suppurate (i.e. form or discharge pus). Once it has spilled into the bloodstream, the infection is systemic.
The cells that have taken up the antigen are dendritic cells, shown in green in this higher-power view
Within the inguinal (draining) node the antigen is quite deep below the surface – the arrows mark the border. More on this next class
------------ in leg muscle at injection site ----------
in draining LN
Antigen (adjuvant) – red/orange
Dendritic cell marker (DEC205)- green
In the first couple of hours the antigen is not yet cell associated, but after two days most of it is internalisedAntigen transport by dendritic cells following intramuscular inoculation
Note the scale bar!
What is an “adjuvant”?
Data from Dupuis et al, “Dendritic Cells Internalize Vaccine Adjuvant
after Intramuscular Injection“ Cellular Immunology 186: 18 (1998)
Antigen fate after i.m. injection
Knowledge of functional lung anatomy is essential for clinicians to deal with infections that overwhelm the normal non-specifc immune defences which keep the alveoli normally sterile. Write a checklist of these defences.
From http://anthrax.radpath.org/Pathogen9.htmlInhaled Antigens: the Lung
Pulmonary Lymphoid System comprises
The bacterial disease anthrax is in the news as an inhaled pathogen. It is a toxigenic bacillus whose details you are not required to know. However, the next two pages make the point that the radiology of the lymph nodes can often give the quickest diagnosis, and reveal the role of the lymphoid organs when non-specific defences have been breached
Pulmonary lymphoid system 1
The infection begins with the inhalation of the anthrax spore. The ability to reach the pulmonary alveolus requires a spore size of less than 5 microns. The spore is engulfed by alveolar macrophages, and is transported through the pulmonary lymphatics to hilar and mediastinal lymph nodes.
Spiral CT through chest. Shows enlarged blood-filled lymph nodes (blue arrows) and fluid surrounding both lungs (red arrows). From http://jol.rsna.org/pr/target.cfm?ID=55
Anthrax bacilli after the spores have germinated, completely filling a pulmonary lymphatic (arrow)Anthrax in a postal worker, USA 2001
With a lymphatic vessel filled like that, it isn’t surprising the outcome sadly was fatal
advancedPulmonary lymphoid system in anthrax
CT imaging demonstrates bulky high-attenuation hilar and mediastinal lymphadenopathy which may produce bronchial and vascular narrowing. Large rapidly-progressive pleural effusions are characteristic. The portal of entry is the airway and the organisms are rapidly transmitted via the lymphatics to the intrathoracic lymph nodes and ultimately to the blood stream. Despite the inhalational acquisition of the disease, the lung parenchyma remains relatively uninvolved.From http://anthrax.radpath.org/Summary2.html
Pulmonary lymphoid system 2
You have probably by now mastered the meaning of “lymphadenopathy” since that has appeared a number of times, but what about “lymphadenectomy”?
Pathologies of lymph noders