Which term describes cytokine signaling that targets nearby cells?

• A. Paracrine (cytokine action)
• B. Autocrine (cytokine action)
• C. Endocrine (cytokine action)
• D. Juxtacrine (cytokine action)

Answer: (A)

Paracrine signaling describes cytokine signaling that targets nearby cells. In this mode, a cell releases cytokines into the local environment and these signaling molecules diffuse a short distance to bind receptors on neighboring cells, triggering a response in those nearby cells within the same tissue. This contrasts with autocrine signaling, where the same cell that releases the cytokine is also the one that responds to it; endocrine signaling, where signals travel through the bloodstream to distant targets; and juxtacrine signaling, which requires direct cell-to-cell contact via membrane-bound signals or gap junctions. So for signaling that affects nearby cells, paracrine is the term.