Which of the following is a non-antibody protein that regulates the immune process?

Cytokines are a broad category of non-antibody proteins that play a critical role in regulating the immune response. They act as signaling molecules that enable communication between cells, driving the immune system's response to pathogens and injury. Cytokines include various types of proteins that can modulate the activity of immune cells, influence the production of antibodies, and promote the inflammatory response.

While monokines, interleukins, and interferons also fall under the umbrella of cytokines, they represent specific subsets or types within that broader category. Monokines are cytokines produced by monocytes, while interleukins serve specifically as signals between leukocytes (white blood cells). Interferons are a group of cytokines that are particularly involved in the antiviral response but are also considered a specific type of cytokine. Thus, the primary term that encompasses all these functions and classifications in a general sense is cytokines, which underscores their diverse roles in immune regulation.