Difference Between Type I and Type II Interferon

The key difference between type I and type II interferon is that type I interferon binds with a cell surface receptor called interferon-α/β receptor (IFNAR) while type II interferon binds with a specific receptor called IFN-γ receptor (IFNGR) complex.

Interferons are cytokines which are produced as a result of viral infections. This name was given since they have the ability to interfere with the viral replication within the host cells. Moreover, interferons cause direct and indirect effects during the infections of bacteria, parasites and fungi. There are two types of interferons as type I and type II interferons based on the type of receptors. They are short glycoproteins. When a virus infects cells, production of interferons is induced. Then, interferons stimulate the synthesis of antiviral proteins in the cell. These antiviral proteins inhibit the multiplication of viral particles. An absence of either the receptor for interferons results in increased susceptibility to virus infection, including increased virus replication and reduced survival.

CONTENTS

1. Overview and Key Difference
2. What is Type I Interferon
3. What is Type II Interferon
4. Similarities Between Type I and Type II Interferon
5. Side by Side Comparison – Type I vs Type II Interferon in Tabular Form
6. Summary

What is Type I Interferon?

Type I interferon is a glycoprotein secreted by infected cells. These type I interferons bind with the common cell surface receptors called interferon-α/β receptor (IFNAR). There are two main types of type I interferons as IFN-α and IFN-β.

There are 13 to 14 subtypes of type I interferons. They are secreted by many cell types, including lymphocytes (NK cells, B-cells and T-cells), macrophages, fibroblasts, endothelial cells, osteoblasts and others The genes coding for type I interferons are located in the chromosome 9 of humans.

What is Type II Interferon?

Type II interferons are the second class of interferons produced predominantly by natural killer cells (NK cells) during the antiviral innate immune response. They are also produced by T helper cells. Type II interferons bind with the IFN-γ receptor (IFNGR) complex.

There is only one type of type II interferons: IFN-γ. IFN-γ is an important component of the innate antiviral response. Genes located on the chromosome12 code for type II interferons.

What are the Similarities Between Type I and Type II Interferon?

• Both type I and type II interferons are short glycoproteins which are cytokines.
• They possess indirect antiviral properties.
• Viral infections trigger the production of interferons.
• They also can elicit immunological responses in the organ.
• Interferons mediate signalling cascades in living organisms.

What is the Difference Between Type I and Type II Interferon?

Based on the receptors they bind, there are two classes of interferons as type I and type II interferons. Type I interferon binds with interferon-α/β receptor (IFNAR) while type II interferon binds with IFN-γ receptor (IFNGR) complex. Thus, this is the key difference between type I and type II interferon. IFN-α and IFN-β are the two types of type I interferon while IFN-γ is the only type of type II interferon.

The below infographic tabulates side by side more differences between type I and type II interferon.

Summary – Type I vs Type II Interferon

Interferons are short glycoproteins/cytokines secreted by infected cells. They possess antiviral, anti-proliferative and immunomodulatory effects. They inhibit virus replication. Moreover, they enhance immune responses. There are two main types of interferons; type I and type II. IFN-α, and IFN-β are type I interferons while IFN-γ is the only type II interferon. Type I interferon binds with a common cell surface receptor called interferon-α/β receptor (IFNAR) while type II interferon binds with a specific receptor called IFN-γ receptor (IFNGR) complex. So, this is the summary of the difference between type I and type II interferon.

Reference:

1. Ivashkiv, Lionel B, and Laura T Donlin. “Regulation of Type I Interferon Responses.” Nature Reviews. Immunology, U.S. National Library of Medicine, Jan. 2014, Available here.
2. Lee, Amanda J., and Ali A. Ashkar. “The Dual Nature of Type I and Type II Interferons.” Frontiers, Frontiers, 21 Aug. 2018, Available here.

Image Courtesy:

1. “1AU1 Human Interferon-Beta01” By Nevit Dilmen – Self created from PDB entry with Cn3D Data Source (CC BY-SA 3.0) via Commons Wikimedia

2. “1HIG Interferon-Gamma01” By Nevit Dilmen – Self created from PDB entry with Cn3D Data Source (CC BY-SA 3.0) via Commons Wikimedia