Step 1: Concept Overview:
Chemokines are small signaling proteins essential for immune cell movement.
Step 2: In-depth Explanation:
- Cytokines are proteins mediating communication between immune cells.
- Chemokines are a cytokine subfamily that induce cell migration (chemotaxis).
- Immune cells (e.g., neutrophils, macrophages) use chemokine gradients to migrate from blood to infected/inflamed tissues.
- Chemokines are specialized cytokines with chemotactic activity.
Step 3: Conclusion:
Chemokines are best defined as specialized chemotactic cytokines, making option (B) correct.