Lymphoid System Flashcards
Where do B cells mature?
Bone Marrow
Where do T cells mature?
Thymus
What areas are considered Primary Lymphoid Tissue?
Central Bone Marrow
Thymus
What areas are considered Secondary Lymphoid Tissue
- Lymph nodes
- spleen
- tonsils (Waldeyer’s ring)
- epithelio-lymphoid tissue (e.g. in bowel/ skin)
- peripheral bone marrow
What are the functions of the Lymph system?
- return lymph to circulation
- prevents accumulation of fluid in tissue (oedema)
- permits cell traffic
- allows cell trapping (i.e. traps abnormal cells in lymph)
- cells can interact with immune system
When does lymphoedema commonly appear?
post axillary surgery for breast cancer
=> no lymph nodes to drain fluid from arm
=> swelling
What is chylous ascites and when does it occur?
- lipid rich lymph
- accumulates in peritoneum
- due to trauma/obstruction
What major lymph node groups must be visualised radiologically?
Mediastinal
para-aortic
How large can lymph nodes become when swollen?
2.5cm
Describe the passage of lymph through a lymph node
IN = afferent lymph vessel
travel round peripheral sinus
diffuse through parenchyma
to EFFERENT lymph vessel
What type of immune cell links the innate and adaptive immune system?
Antigen Presenting Cells (APC’s)
present antigen to mature B/T cells in lymph node to create memory bank cells and Ab
B Cells accumulate where in lymph nodes?
Germinal Centres
- allows them to differentiate into IgG and memory B cells
Aside from B and T cells, what other cells are found in a lymph node?
Natural Killer Cells (NKCs)
Macrophages
APCs
Dendritic Cells
What surface antigens are used to differentiate B and T lymphocytes on immunophenotyping?
B cell - CD20
T cell - CD3
What are the potential causes of lymphadenopathy?
- local inflammation (e.g. bacterial infection)
- systemic inflammation (e.g. viral infection, autoimmune)
- malignancy (haem or non-haem)
- metastatic disease
OTHERS: sarcoidosis
What percentage of sarcoidosis cases experience lyphadenopathy
15%
Sarcoidosis can potentially hide a malignancy in a lymph node. TRUE/FALSE?
TRUE
- granulomatous disease can make it difficult to identify other pathology in node
How can regional lymphadenopathy be identified on examination?
- red lines may extend from inflamed lesion due to pattern of draining
=> lymphangitis - superficial lymphadenopathy (e.g. first sign of underling cancer e.g. breast)
A predominant B cell response in a lymph node that is enlarged would make you consider what causes?
- autoimmune
- infection
A predominantly phagocytic response in an enlarged lymph node would make you consider what causes?
Drainage of a tumour site
A T cell response in an enlarged lymph node was cause you to consider what pathology?
- viral infection
- drug induced (phenytoin)
GIve an example of a disease during which the spleen is more likely to rupture? How is this prevented?
- glandular fever (EBV)
- encourage patients to not participate in contact sport
What types of tissue make up the spleen and what is found in each?
Parenchyma includes red pulp and white pulp
Red pulp contains sinusoids and cords which have cells in transit
White pulp contains T helper cellls
What is the main function of the spleen?
Filters blood like lymph node filters lymph
