The Lymphoid System

Question 1

Where do lymphoid cells originate?

Answer 1

Haemopoeitic stem cells in the foetal liver or postnatal bone marrow

Question 2

What are the central (primary) lymphoid tissues?

Answer 2

Bone marrow and thymus

Question 3

What are the peripheral (secondary) lymphoid tissues?

Answer 3

Lymph nodes, spleen, tonsils, epithelia-lymphoid tissues and bone marrow

Question 4

Describe lymph nodes

Answer 4

Small oval bodies up to 2.5cm in diameter located along the course of lymphatic channels

Question 5

Describe lymphatic channels

Answer 5

Blond-ending vascular channels that collect fluid from tissues and return it to the blood stream. Fluid moves passively but there are valves to ensure the correct direction of flow

Question 6

How does lymph enter the lymph node?

Answer 6

Through the afferent channel in to the peripheral sinus

Question 7

Where does lymph drain to?

Answer 7

Through the efferent vessel to the:
cisterna chyli/ thoracic duct
L. jugular, subclavian or bronchomedial trunks
R. jugular, subclavian or bronchomedial trunks

Question 8

Where to arterial and venous vessels enter/exit the lymph node?

Answer 8

Hilum

Question 9

What are the functions of the lymphatic system?

Answer 9

Return lymph to circulation
          Fluid homeostasis
          Prevents oedema
Filter lymph before returning it to circulation
         Cell traffic
         Immunity

Question 10

Where is lymph filtered/

Answer 10

Lymph node parenchyma

Question 11

What type of immune cells are in the lymph nodes

Answer 11

B-lymphocytes
T-lymphocytes (helper and killer)
NK cells
Macrophages, antigen-presenting cells, dendritic cells
Endothelial cells

Question 12

What CD codes are for B cells?

Answer 12

CD20 and CD79a

Question 13

What CD codes are for plasma cells?

Answer 13

CD138

Question 14

What CD codes are for T cells?

Answer 14

CD3

Question 15

What CD codes are for T-helper cells?

Answer 15

CD4

Question 16

What CD codes are for T-cytotoxic cells?

Answer 16

CD8

Question 17

What CD codes are for NK cells

Answer 17

CD56

Question 18

Where in the lymph node are B cells mainly found

Answer 18

peripheral follicles

Question 19

Where in the lymph node are T cells mainly found?

Answer 19

Centrally

Question 20

What can superficial lymphadenopathy be a sign of?

Answer 20

Underlying malignancy

Question 21

What does generalized lymphadenopathy suggest?

Answer 21

Systemic inflammatory process or widespread malignancy (lymphoma or leukaemia)

Question 22

What are the causes of lymphadenopathy

Answer 22

Local inflammation (infection, vaccination, trauma)
Systemic inflammation (infection, autoimmune)
Malignancy (haematological, metastatic)
Sarocoidosis, Castlemans disease, drugs

Question 23

Describe the spleen’s size and location

Answer 23

High in the LUQ

150-200g

Question 24

Describe the 2 key aspects of the spleen

Answer 24

Diaphragmatic surface

Visceral surface- left kidney, gastric fundus, tail of pancreas, splenic flexure of colon

Question 25

What causes splenic rupture

Answer 25

Trauma | Disease

Question 26

Describe the structure of the spleen

Answer 26

Encapsulated organ | The parenchyma contains white and red pulp

Question 27

What does red pulp contain?

Answer 27

Sinusoids and cords

Question 28

Describe splenic sinusoids

Answer 28

Fenestrated, lined by endothelial cells and supported by hoops of reticulin

Question 29

Describe splenic cords

Answer 29

Contain macrophages, fibroblasts and some cells in transit

Question 30

What is the role of the spleen?

Answer 30

Detect, retain and eliminate unwanted/dangerous material | Facilitate immune responses to blood borne antigens

Question 31

What does the white pulp make up?

Answer 31

Peri-arteriolar lymphoid sheath containing CD4+ lymphoid cells

Question 32

What are the features of splenic enlargement?

Answer 32

Dragging sensation in LUQ Discomfort with eating Pain if infarction Hypersplenism

Question 33

What are the 3 features of hypersplenism?

Answer 33

Splenomegaly Fall in one or more cellular components of blood Correction of cytopenias by splenectomy

Question 34

What are the causes of splenomegaly

Answer 34

Infection:- EBV, malaria, TB, brucellosis, leishmaniasis Portal Congestion:- hepatic cirrohosis, portal/splenic vein thrombosis, cardiac failure Haematological Disease:- lymphoma/leukemia, haemolytic anaemia, ITP, myeloproliferative disorders Inflammatory:- RA, SLE Storage diseases:- Gaucher's, Niemann-Pick disease Miscellaneous:- Amyloid, tumours, cysts

Question 35

What are the causes of hyposplenism?

Answer 35

Splenectomy, coeliac disease, sickle cell disease, sarcoidosis, iatrogenic

Question 36

What are the red cell features of hyposplenism?

Answer 36

Howell-Jolly Bodies | Other abnormalities