**Core Concept:** Chemokines are a family of small cytokines that play a crucial role in the immune system by directing the migration of immune cells to sites of inflammation and infection. They are further classified into four subfamilies: C, CC, CXC, and CX3C, based on the distribution of cysteine residues in their amino acid sequences.

**Why the Correct Answer is Right:** Interleukin-8 (IL-8) is an example of a CXC chemokine. In this case, the "C" in CXC stands for "Cytokine," while the "X" represents the two consecutive cysteine residues. IL-8 is produced by various cell types, including macrophages, endothelial cells, and neutrophils, and is involved in the recruitment and activation of neutrophils at the site of inflammation and infection.

**Why Each Wrong Option is Incorrect:**

A. Interleukin-1 beta (IL-1β) is an example of a C-reactive protein (CRP), which is a different group of acute-phase reactants involved in the inflammatory response. CRPs are proteins produced by the liver in response to inflammation or infection, whereas chemokines like CXC chemokines are cytokines secreted by various cell types.

B. Interleukin-8 is not an example of an alpha chemokine, which are a group of chemokines that have a high affinity for the chemokine receptor CXCR2. CXC chemokines like IL-8 do not exclusively belong to the alpha chemokine group and are found in both alpha and beta chemokine groups.

C. Interleukin-1 beta (IL-1β) is an example of a beta chemokine, which is a group of chemokines that have a high affinity for the chemokine receptor CCR2. Beta chemokines are not the same as CXC chemokines like IL-8.

D. Interleukin-8 is not an example of a delta chemokine, which are a subgroup of chemokines that have a high affinity for the chemokine receptor CXCR1.

**Clinical Pearl:** Chemokines play a critical role in the recruitment and activation of immune cells to the site of inflammation or infection, thereby facilitating the immune response. Different chemokine subtypes target specific chemokine receptors, which helps to fine-tune the immune response and prevent excessive inflammation. Understanding the classification of chemokines (alpha, beta, delta, gamma, etc.) is crucial for understanding the role of chemokines in the immune system and their interactions with chemokine receptors.