What is interferon?

What is interferon?

• A. Antibodies secreted by B cells.
• B. Proteins released from infected cells that warn neighboring cells.
• C. Complement proteins that digest pathogens.
• D. Cytokines secreted by macrophages to recruit neutrophils.

Answer: (B)

Interferon is a signaling protein (a cytokine) released by virus-infected cells to warn neighboring cells. When neighboring cells detect interferon, they gear up antiviral defenses, turning on genes that help block viral replication and make them less susceptible to infection. It also helps coordinate the immune response by increasing antigen presentation and activating natural killer cells. This warning-and-defense role is why the correct description is “proteins released from infected cells that warn neighboring cells.” Antibodies secreted by B cells are immune proteins that target pathogens directly. Complement proteins are part of a cascade that helps digest pathogens. Cytokines secreted by macrophages to recruit neutrophils describe chemokines or inflammatory signals that attract immune cells, not interferon.

Interferon is a signaling protein (a cytokine) released by virus-infected cells to warn neighboring cells. When neighboring cells detect interferon, they gear up antiviral defenses, turning on genes that help block viral replication and make them less susceptible to infection. It also helps coordinate the immune response by increasing antigen presentation and activating natural killer cells. This warning-and-defense role is why the correct description is “proteins released from infected cells that warn neighboring cells.”

Antibodies secreted by B cells are immune proteins that target pathogens directly. Complement proteins are part of a cascade that helps digest pathogens. Cytokines secreted by macrophages to recruit neutrophils describe chemokines or inflammatory signals that attract immune cells, not interferon.