Lymph node and spleen

Question 1

What drains where?

Answer 1

Question 2

Sentinel lymph node significance ?

Answer 2

The first lymph node (or group of lymph nodes) to which cancer cells are most likely to spread

• identified by dye or radioactive isotopes

Question 3

Lymph node anatomy

Answer 3

• Node is surrounded by connective tissue CAPSULE
• AFFERENT LYMPHATICS penetrate the capsule and drain into SUBCAPSULAR SINUS
• Lymph from subcapsular sinus percolates THROUGH THE NODE
• Cell traffic, interactions for immune response
• Allows antigenic material to interact with fixed lymphoid tissue
• Lymph enters MEDULLARY CORDS and SINUSES
• Sinuses merge at HILUM and form EFFERENT LYMPHATICS
• Lymph rejoins extranodal lymphatic circulation

Question 4

Lymph node microarchitecture

Answer 4

CORTEX
Nodules of B lymphocytes arranged in follicles (primary / secondary)

PARACORTEX
Mainly T lymphocytes
Forms interfollicular tissue which surrounds follicles and extends out and merges with medulla

MEDULLA
Cords and sinuses draining into hilum

Question 5

Primary vs secondary follicles in lymph nodes

Answer 5

Primary (sleeping)
- Small quiescent lymphocytes
- Unstimulated
- No germinal centre

Secondary (reactive)
- Activated follicles
- Reactive
- Germinal centre

Question 6

Role of follicular dendritic cells ?

(not to be confused with dendritic cells)

Answer 6

• Provide architectural support to germinal centres
• Facilitates debris removal through secretion of bridging factor
• Macrophages come and gobble up debris
• Antigen capture for memory B cells
• Mesenchymal origin

Question 7

What happens in a follicle?

Answer 7

Quiescent B cells are activated in response to antigenic challenge
Antigen-antibody complexes are captured by follicular dendritic cells (FDCs)
FDCs are specialised antigen-presenting cells
They are mesenchymal and form meshworks through the germinal centre

Antigens on the FDCs are presented to naive B cells
T helper cells assist

Question 8

Centroblast =

Answer 8

Proliferating B cell in dark zone

Differentiates into a centrocyte

Question 9

Positively selected B cells go one of three ways:

Answer 9

1. Reenter dark zone and keep proliferating (and expressing cMyc to regulate GC formation)
2. Differentiate into plasma cells
3. Differentiate into memory B cells

Question 10

4 types of tonsils

Answer 10

Question 11

Where does interaction occur in tonsils?

Answer 11

Crypt lined with epithelium

Question 12

When caseous necrosis is present, assume ________ until proven otherwise

Answer 12

Mycobacterial infection (due to TB)

Question 13

Lymphomas

Answer 13

Non Hodgkin’s Lymphomas (NHL)
Most common form of lymphoma
A diverse group of diseases
B cell lymphomas
- Most common form of NHL
- Low-grade forms
- High-grade forms
T cell lymphomas
- Less common
- More complex classification

Hodgkin’s lymphomas
Less common than NHL
Different types – classical and nodular lymphocyte-predominant
Also of B cell origin
Usually has a very good prognosis