Interferons are small polypeptides produced mainly by virus-infected cells. The main functions are of interferon is to interact with uninfected cells and render them resistant to infection by increasing the production of enzymes that digest viral nucleic acids. The interferon can then also cause an increase in MHC (Major Histocompatibility Complex) Class I and II expression on all cells, so if they are infected, the immune system can recognise the infection and take further steps of limiting viral replication. An example is the lysis of the infected cell by [[Blood Cell Overview|cytotoxic T lymphocytes]], or the induction of apoptosis by Natural Killer Cells.
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Interferons are small polypeptides produced mainly by virus-infected cells. The main functions are of interferon is to interact with uninfected cells and render them resistant to infection by increasing the production of enzymes that digest viral nucleic acids. The interferon can then also cause an increase in MHC (Major Histocompatibility Complex) Class I and II expression on all cells, so if they are infected, the immune system can recognise the infection and take further steps of limiting viral replication. An example is the lysis of the infected cell by [[T cells|cytotoxic T lymphocytes]], or the induction of apoptosis by [[Natural Killer cells|Natural Killer Cells]].