T and B cells, Cytokines and Dendritic cells

Question 1

Describe Cytokines

Answer 1

They are usually small polypeptides released by cells in response to an activating stimulus. They can behave like autocrine, paracrine or endocrine manner.

Question 2

Describe chemokines

Answer 2

A class cytokines that has chemoattractant properties (induces cells to migrate towards the source)

Question 3

What are the two main groups of chemokines?

Answer 3

CC and CXC

Question 4

Describe features of interleukin 8

Answer 4

It is a chemotatic factor, secreted by monocytes and macrophages and activates and recruits neutrophils and T cells to the site of infection.

Question 5

Describe features of interleukin 2

Answer 5

It is released by T cells and activates T cells, causing them to multiply and expand in numbers

Question 6

Describe features of interleukin 4

Answer 6

It is released by T cells and activates B cells, causing them to switch to producing IgE, therefore important in allergy.

Question 7

Describe features of interferon gamma

Answer 7

Activates strong cell mediated responses. For example it causes the up regulation of MHC class 1 and 2

Question 8

Describe features of TNF alpha (Tumor necrosis factor alpha)

Answer 8

It is a main pro inflammatory cytokine. It activates vascular endothelium, increases vascular permeability.

Question 9

Describe features of Interleukin 12

Answer 9

Activates NK cells and induces the differentiation of CD4 cells into TH1 cells.

Question 10

How can neutrophils access infection sites?

Answer 10

Diapedesis (passage of cells through intact vessel walls). This can be encouraged by IL8

Question 11

Describe when TNF alpha is good and when is it bad

Answer 11

Good - when involved in a local pro-inflammatory reaction. Bad - when it becomes systemic as this increases endothelial permeability and multiple organ failure.

Question 12

Describe how T cells induce self proliferation

Answer 12

Naive T cells express low affinity IL-2 receptors, then activated T cells express high affinity IL-2 receptors and secrete IL-2. The binding of the IL-2 to its receptors sends a signal to the cell to proliferate

Question 13

Describe what CD4 cells differentiate into

Answer 13

T helper cell 1 (TH1 cell) and T helper cell 2 (TH2 cell

Question 14

What are TH1 cells involved in?

Answer 14

Macrophage (mainly) and B cell (slightly) activation. (activating immune response cells)

Question 15

What are TH2 cells involved in?

Answer 15

Secretion of cytokines and chemokines to activate B cells to make antibodies

Question 16

What do TH1 and TH2 secrete?

Answer 16

TH1 - interferon gamma. TH2 - secretes IL4

Question 17

What does TH17 cells secrete?

Answer 17

Secretes interleukin 17 which becomes raised in a number of autoimmune conditions

Question 18

What is the function of dendritic cells?

Answer 18

Professional antigen presenting cells that sit at the interface between the innate and adaptive immune response

Question 19

What are the other names for dendritic cells?

Answer 19

Langerhan cells in skin and follicular dendritic cells (LDC) in lymphnodes

Question 20

Why have FDC been found in lymph nodes holding onto antigens for long periods of time?

Answer 20

They can sit here for a long period of time so they can provide a long term stimulus and contribute to making a memory response. Agtigen ready in case you need to re stimulate an immune response

Question 21

Affinity maturation is driven by?

Answer 21

The interactions of the FDC

Question 22

How can dendritic cells determine what is foreign?

Answer 22

They express Patter Recognition Receptors (PRR) which have the ability to detect what is self or non self.

Question 23

What are the main PRRs?

Answer 23

Toll-like receptor (TLR) family

Question 24

Give an example of a TLR and what it detects

Answer 24

TLR4 - detects lipopolysaccharides and heat shock proteins