5: IMMUNITY: cytokines and inflammation

Cytokines?

Protein molecules secreted by cells of the immune system

Bind to receptors onto target cell

How are cytokines produced?

More than 1 type of cell and in different tissues

Effects of cytokines upon target cells?

Cell proliferation

Cell differentiation

Haematopoiesis

Give example cytokine xe

interleukin 1

interleukin 6

TNF alpha

Describe effects of interferon on target cell

Cells activate factors that interfere with viral replication

Cells produce Rnase enzymes

Cells downregulate protein translation

Cells upregulate pro apoptotic proteins

Give 3 triggers of inflammation

infections

trauma

foreign bodies

physical and chemical agents

Function cytokines released during inflammation

increase white blood cells numbers

vasodilation

increase capillary permeability

Name 2 cells that cause inflammation

mast cells

macrophages

mast cells?

respond to tissue damage and release histamine

macrophages?

produce cytokines in response to pathogens

give 3 benefits inflammation

isolation damaged area

mobilisation effector cells

healing

give 2 disadvantages of inflammation

allergy

autoimmunity

Extravasation?

During inflammation, endothelial cells act as a gate-keeper by increasing adhesion molecules that let white blood cells stick, cross the vessel wall, and enter tissue

Describe the acute phase response (livers reaction to inflammation due to cytokinesis)

• Local inflammation triggers macrophages to release IL-6.

• IL-6 stimulates the liver to produce acute phase proteins (e.g., complement, C-reactive protein).

• Positive acute phase reactants ↑ increase in level.

• Negative acute phase reactants ↓ decrease in level.

Describe fever

• Part of the acute phase response

• White blood cells (e.g., macrophages) release pyrogens: IL-1, TNF-α, IL-6

• Pyrogens act on the hypothalamus

• Hypothalamus increases body temperature