Definitions 5

Question 1

What is a dendritic cell?

Answer 1

A special type of cell found in tissues that boosts the immune response by showing antigens on its surface to other cells of the immune system.

Question 2

What is a follicular dendritic cell?

Answer 2

Specialized type of antigen-presenting dendritic cells that are largely restricted to lymphoid follicles.

Question 3

What is a naive T cell?

Answer 3

Know what antigen they’re looking for but haven’t encountered it yet (don’t know what to do with it when they find it)

• Have to be activated in lymph node
• Blood > HEV > 2nd lymphoid tissues > efferent lymphatics > blood

Question 4

What is a memory T cell?

Answer 4

A class of T cells that persists after having previously responded to antigenic stimulation

Question 5

What is a T Helper 1 cell?

Answer 5

Respond to intracellular pathogens such as mycobacterium bovis, brucella, leishmania, toxoplasma and viruses.

• Driven by CD4+ T cells (and CD8+ T cells), T FH cells, and B cells
  - CD4+ cells produce: IL-2, TNF-alpha and INF-gamma
  - Induced by production of IL-12 from DC
• Activate macrophages to kill intravesicular pathogens
• Secretion of IL-3 and GM-CSF

Question 6

What is a T Helper 2 cell?

Answer 6

Respond to parasitic helminths
- multicellular, macro pathogens - roundworms and flatworms

• Allergic responses
• Cell types: CD4+ T cells, B cells, eosinophils, macrophages, mast cells

Question 7

What is a T Helper 17 cell?

Answer 7

Aid in maintaining homeostatic conditions
- maintain gut-microbiome balance

• Associated with response to extracellular bacteria and fungi
• Mediated by CD4 (Th17) cells and neutrophils
• Produce IL-17 A/F and IL-22

Question 8

What is a T Follicular Helper cell?

Answer 8

• Will develop under multiple T helper environments
  - supports antibody production
• Driven by IL-6 and IL-21
  - Produce IL-21
  - Found within germinal centers
  - Enhance B cell responses, isotype class switch

Question 9

What is a T regulatory cell?

Answer 9

Suppress responses and prevent autoimmunity
- Natural T reg
- generated in the thymus
- Inducible T reg
- generated in the periphery
- Produce immunomodulatory cytokines

Suppressive mechanisms (target T cells, B cells, and DC)
- inhibit their function via: inhibitory receptors, cytokine production, depriving survival signals, direct killing

Question 10

What is an NK cell?

Answer 10

Natural Killer cell
- effector lymphocyte of the innate immune system
- control several types of tumors and microbial infections by limiting their spread and subsequent tissue
damage

Question 11

What is interferon gamma?

Answer 11

It is the major activator of macrophages through superoxide and nitric oxide production

Augments antigen presentation through both MHC I and MHC II pathways increasing the immunogenicity of tumor cells and enhancing their detection and killing by immune surveillance and effector mechanisms

Question 12

What is IL4?

Answer 12

Anti-inflammatory cytokine that functions by suppressing the pro-inflammatory milieu

Question 13

What is IL12?

Answer 13

An immune cell stimulator that promotes differentiation and proliferation of T cells and enhances the production of interferon gamma

Question 14

What is apoptosis?

Answer 14

Programmed cell death (not inflammatory)

Question 15

What is necrosis?

Answer 15

Non-programmed cell death (inflammatory)

Question 16

What is type 1 interferon?

Answer 16

Cytokines that play an essential role in inflammation, immunoregulation, tumor cell recognition and T cell responses.

Question 17

What is CD3?

Answer 17

A protein complex and T cell co-receptor that is involved in activating both the cytotoxic T cell and T helper cells.

Composed of 4 distinct chains

Question 18

What is CD4 T cell/T helper cell?

Answer 18

• Express a T cell receptor composed of alpha-beta chains
• Recognize antigen in the context of MHC II receptor
• Develop into various effector phenotypes
  - dependent on the type of pathogen encountered and inflammatory signals (cytokines)

Question 19

What is CD8/CTL cell?

Answer 19

Kill virus-infected cells and produce antiviral cytokines such as interferon gamma.