Which of the following is/are Type I interferon? a. NOD-receptors b. IFN-gamma c. TLR4 d. cytokines e. IFN-beta
The correct answer and explanation is:
Correct answer: e. IFN-beta
Explanation (300 words):
Interferons (IFNs) are a group of signaling proteins (cytokines) made and released by host cells in response to the presence of pathogens, such as viruses, bacteria, parasites, or tumor cells. They play a crucial role in the immune response by interfering with viral replication and modulating the immune system.
There are three main types of interferons:
- Type I interferons, including IFN-alpha and IFN-beta
- Type II interferon, which is IFN-gamma
- Type III interferons, such as IFN-lambda
Type I interferons are primarily involved in antiviral defense. They are produced by almost all nucleated cells in response to viral infections. IFN-beta, specifically, is a Type I interferon produced mainly by fibroblasts and epithelial cells. It helps limit viral spread by inducing antiviral proteins in infected and nearby cells, thereby creating an antiviral state.
Let’s now briefly analyze the other options:
- a. NOD-receptors: These are NOD-like receptors, a type of intracellular pattern recognition receptor (PRR) that detects microbial components inside the cell. They are not interferons.
- b. IFN-gamma: This is a Type II interferon, produced mainly by T cells and NK cells. It is important for activating macrophages and coordinating adaptive immunity, but not a Type I interferon.
- c. TLR4: This is Toll-like receptor 4, a membrane-bound PRR that recognizes lipopolysaccharide (LPS) from gram-negative bacteria. It can stimulate the production of interferons but is not an interferon itself.
- d. Cytokines: This is a broad term referring to all signaling molecules like interferons, interleukins, and tumor necrosis factors. While Type I interferons are cytokines, the term “cytokines” itself is not specific to Type I interferons.
Therefore, the only correct and specific Type I interferon listed is e. IFN-beta.