Lecture 2 - Immune System Tissues

Question 1

What lineage produces members of the innate immune response?

Answer 1

Myeloid/granulocytic make phagocytic ‘troopers/gorgers’

Question 2

What lineage produces members of the adaptive immune response?

Answer 2

Lymphoid/non-granulocytic. Make non-phagocytic antigen speciific,’ generals/directors’

Question 3

What are the three expceptions to the general lineage rule?

Answer 3

Large granular lymphocytes (NK cells, gamma delta T cells, innate). Monocytes (innate but not really granulocytic). Dendritic cells

Question 4

What cells would you find in the peripheral blood through venepuncture?

Answer 4

Neutrophils, lymphocytes, monocytes, eosinophils, basophils

Question 5

What cells would you find in the lymphoid tissue through biopsy?

Answer 5

Lymphocytes, antigen presentic cells (macrophages, dendiritic cells)

Question 6

What cells would you find in non peripheral blood or lymphoid tissue through biopsy?

Answer 6

Plasma cells, mast cells, APCs

Question 7

Whats the difference between primary/central lymphoid organs vs secondary/peripheral lymphoid organs?

Answer 7

Immune cells generated in primary/central LO (BM, thymus, fetal liver) and immune responses are initiated in peripheral/secondary LO (spleen, LN, tonsils, mucosa associated lymph tiss MALT ie appendix, peyer’s patches)

Question 8

What are neutrophils?

Answer 8

Phagocytic WBC. Enter infected tissues in large numbers and engulfs/kills pathogens

Question 9

What are monocytes?

Answer 9

Precursors for macrophages. Bean shaped nucleus

Question 10

What are macrophages?

Answer 10

Phagocytic cells found in most tissues. From monocytes contribute to innate immunity and early nonadapative host defense

Question 11

What are dendritic cells?

Answer 11

Highly functional antigen presenting cells with branched dendrites, most potent stimulators of T cell responses

Question 12

What are natural killer cells?

Answer 12

Lymphoid cells that kill tumor cells and certain virus infected cells

Question 13

What are the two types of T cells?

Answer 13

Helper/CD4 which help B cells make Ig isotypes other than IgM and IgD and help cytotoxic lymphocytes (CTLs) become killer cells. Cytotoxic/CD8 kill virus-infected host cells

Question 14

How do T cells develop?

Answer 14

Lymph progenitors migrate from BM to thymus -> pre T -> double positive thymocytes (CD8 and CD4) which become either CD8 (cytotoxic) or CD4 (helper). They then migrate out of thymus into peripheral lymphoid tissues

Question 15

What are cytokines? What 3 things can they do?

Answer 15

Small secreted proteins that are made by cells that regulate the differentiation, proliferation and/or survival of other cells. Some regulate hematopoiesis (some specific to lineage) and some regulate other aspects of the immune response (eg T and B cell activation and differentiation) some promote inflammatory responses at sites of infection

Question 16

Which cytokine is primarily responsible for T and B cell development? RBC formation? Monocytes and granulocytes?

Answer 16

IL 7 for lymphocytes, EPO for RBCs, M-CSF and GM-CSF for mono and granulocytes

Question 17

What shared protein is utilized by many different cytokine receptors?

Answer 17

Common gamma chain gc

Question 18

Where are immune responses usually initiated?

Answer 18

In draining lymph nodes and/or the spleen.

Question 19

What did the experiment with the thoracic duct cannulation show?

Answer 19

The vast majority of lymphocytes re-circulate (blood-lymph-blood) every 1-2 days so that they continuously come into contact with different sites potentially containing pathogen-associated antigens

Question 20

What are the two ways in which fluids/cells can enter a lymph node?

Answer 20

From skin/peripheral locations enter via afferant lymphatic vessel. Leukocytes in blood enter via high endothelial venules (HEVs)

Question 21

How do cells exit a lymph node?

Answer 21

Via afferent lymphatic vessel which connects to the thoracic duct

Question 22

How are lymphocytes trafficked into lymph nodes?

Answer 22

Express surface proteins (eg L selectin, CCR7) which bind to ligands on HEVs and allow entry into B/T cell zones of the lymph node

Question 23

Describe the morphology of a lymph node

Answer 23

B cell rich zones called follices. T cell rich zones called the paracortex. Whan an antigen enters the LN (usually byway of dendritic cell via afferent lymphatic vessels) lymphocyte activation begins. Dendirtic cells and macrophages migrate to paracortical area to interact with T cells and B cells in their zones can form germinal centers.

Question 24

Describe the morphology of the spleen

Answer 24

T cells surround the central arteriole in the periarteriolar lymphoid sheath (PALS). B cells situated in follices around follicular arterioles and marginal sinus. T and B cell zones make up the white pulp. Red pulp is made of vascular sinusoids filled with RBCs, macrophages and dendritic cells

Question 25

What happens to a blood borne antigen which enters the marginal zone of the spleen?

Answer 25

Encounters specialized splnic macrophages and dendritic cells which clear blood of bacteria and pathogens (and damaged RBCs). Macrophages also clear opsonized bacteria

Question 26

Why are individuals without a spleen susceptible to infection? And with what kind of bacteria?

Answer 26

Lack the specialized slpenic B cells and macrophages. Susceptible to infection with encapsulated bacteria such as pneumococcus and meningococcus which are usually filtered through the marginal zone

Question 27

Where are lymphocytes found in the mucosal immune system?

Answer 27

Peyer’s patches (mostly B), lamina propia and intraepithelial collections (mostly T)

Question 28

What are M cells and what do they do?

Answer 28

M cells lie above Peyer’s patches in mucosal immune system and internalize antigens which are delivered to the peyer’s patches

Question 29

What reaction does oral exposure to angtigens elicit in the mucosal immune system?

Answer 29

B cells make IgA antibodies

Question 30

How do leukocytes invade infected tissues from the blood?

Answer 30

Tissue macrophages recognize microbes and produce cytokines which act on epithelial cells lining small blood vessels and lymphatics. The epithelial cells upregulate expression of adhesion molecules. Circulating monocytes, dendritic cells and neutrophils bind loosely to at first and roll to an area that favors invasion, then form tighter bound with integrins, enter the tissue without disrubting the cell membrane, and chemotax to the site of infection

Question 31

How are antigens in epithlium/connective tissue and blood-borne antigens captured?

Answer 31

Lymph node captures antigens from epithelium/connective tissue. Antigen-presentinc cells in spleen capture blood borne antigens

Question 32

How do we characterize and enumerate cell types?

Answer 32

Flow cytometry. Label cells according to markers