Question

What are interferons?

Answer 1

Interferons are a group of proteins that play a major role in the immune system during the first line of defense (innate immunity), primarily against viral infections. Interferons are of two types;

• Type I Interferons, that include interferon-alpha and interferon-beta are produced by virus-infected cells, thereby signaling to the immune system about the viral infection and need for action.
• Type II Interferons, including interferon-gamma, is produced by specific activated T-cells or NK (Natural Killer)-cells.

Interferons have multiple functions in the immune system,

• Alert the immune system and the neighboring cells when a cell gets infected by the virus.
• Interferons increase the expression of class I MHC molecules and thus promote recognition by cytotoxic T-cells. Interferons also activate NK-cells.
• Interferons also increase the expression of class II MHC molecules on the antigen presenting cells, thus promoting the activity of helper T-cells.
• Interferons also activate functions of macrophage to resist viral infection and to kill the infected cells.