Leukocytes and organization of the immune system

Question 1

What are the main roles of phagocytes?

Answer 1

Defense against bacteria, fungal infections, and tumors

Question 2

What are alternate names for neutrophils and their lifespan?

Answer 2

Also called polys, pmns, segs; only live for a few hours in peripheral blood

Question 3

Where are eosinophils found and what are their functions immunologically?

Answer 3

They are usually found in the tissues (not systemic circulation) and wage hypersensitive reactions against parasites, allergens, and some tumors

Question 4

Where are basophils found and what are their functions immunologically?

Answer 4

They are predominantly found in tissues and are involved in immediate hypersensitivity reactions and release heparin and histamine.

Question 5

What is the difference between a monocyte and a macrophage and what are their roles?

Answer 5

Monocytes exist in the peripheral blood and macrophages exist in the tissues. Both are involved in ingestion of foreign substances and the presentation to the adaptive immune system. They appear more vacuolated usually than basophils.

Question 6

Where are mast cells found and what are their functions?

Answer 6

Found predominantly in bone marrow, skin, and the mucosal epithelium,, have histamine and powerful affinity for IgE

Question 7

During what stages of differentiation is SCF found?

Answer 7

Pluripotent stem cells

Question 8

During what stages of differentiation is IL-3 found?

Answer 8

From stem cells up to myeloblasts

Question 9

During what stages of differentiation is GM-CSF found?

Answer 9

From progenitor cells through the seg stages

Question 10

During what stages of differentiation is G-CSF found?

Answer 10

From late progenitor cells through the seg stages

Question 11

What is the difference between a circulating seg and a marginating seg?

Answer 11

Marginating cells travel along the edges of the endothelium and enter the tissues readily; stress causes marginating cells to enter the tissue

Question 12

What are the primary lymphoid organs and their roles?

Answer 12

The bone marrow (where B cells mature) and the thymus (where T cells mature)

Question 13

What are the secondary lymphoid organs and to what do they respond immunologically?

Answer 13

Lymph nodes respond to tissue antigens
The spleen responds to blood antigens
MALT responds to mucosal antigens

Question 14

By what means do lymph cells leave the circulation?

Answer 14

Through high endothelial venules

Question 15

What are the afferent and efferent lymphatic pathways?

Answer 15

Afferent pathways enter a lymph node and efferent pathways are the roads back to the circulation via the thoracic duct.

Question 16

What are the primary roles of the lymph vessels?

Answer 16

They ferry blood that enters the tissues from hydrostatic pressure into the bloodstream again; lymphocytes and dendritic cells use lymph vessels to travel to lymph nodes

Question 17

What are the main regions of the lymph node and the relevance of the various domains?

Answer 17

The capsule encloses the node
The subscapular space accepts afferent lymph and is the site of most metastasis
The follicles in the cortex is where B cells mature
The paracortex is where T cells reside
The medullary cord is where plasma cells reside

Question 18

Where are B lymphocytes predominantly found and how much of circulating lymphocytes do they make up?

Answer 18

Exist mostly in the cortex of lymph nodes, the white pulp of the spleen, and in other lymph

Question 19

How to naive B cells apppear and where are they found?

Answer 19

They express both IgM and IgD and can respond and present antigen; they are present in primary lymphatic follicles

Question 20

What are the roles and cell types in a germinal center?

Answer 20

Antigenic activation promotes B cell differentiation. The dark zone is the site of proliferating centroblasts and the light zone is where proliferating centrocytes; selection of self antigens occurs here

Question 21

How does reactive hyperplasia occur?

Answer 21

Germinal centers in a lymph organ overreact to antigen and proliferate excessively

Question 22

What is the role of the red pulp of the spleen?

Answer 22

Filters the blood for antigens by macrophages and for the destruction of RBCs

Question 23

What are the two types of circulation in the red pulp of the spleen?

Answer 23

The open circulation runs through the capillaries into splenic cords to sinusoids and thereafter to veins
The closed circulation is a direct passage from the pencillary arteries to the sinuses and traebecular veins thereafter

Question 24

What are the roles of white pulp?

Answer 24

The white pulp is predominately immunologic in nature with T cell populations and B cell germinal centers. It is demarcated from the red pulp by the peri-areolar lymphoid sheath

Question 25

How can one determine if a patient has a spleen or not?

Answer 25

1) Patient has a predominant risk to bacterial infection

2) Howell-Jolly bodies appear in blood smears, these are nuclear residues left in RBCs

Question 26

What are the embryological origins of the thymus?

Answer 26

The third and fourth pharyngeal pouches

Question 27

What are the main cell populations found in the thymus?

Answer 27

T cells, thymic epithelial cells, macrophages, and dendritic cells

Question 28

What is DiGeorge syndrome?

Answer 28

It is a deletion of 22q11.2; the thymus fails to develop and patients have profound congential immunological deficiencies with respect to T cells

Question 29

What is lymphoblaastic lymphoma?

Answer 29

It is a malignancy of immature T cells with an anterior chest wall mass

Question 30

What is the main antibody produced by MALT?

Answer 30

IgA