Which cells are primarily involved in the chronic phase of inflammation?

The correct choice is macrophages, as they play a crucial role in the chronic phase of inflammation. During this phase, macrophages dominate the inflammatory response by continuing to clean up debris from tissue damage and facilitating tissue repair. Unlike neutrophils, which are primarily involved in the acute phase and respond quickly to sites of infection or injury, macrophages persist in the tissue for a longer duration and are integral to the transition from acute to chronic inflammation.

Macrophages help maintain inflammation by releasing a variety of cytokines and growth factors that recruit other immune cells to the site and contribute to the healing process. They also play a role in shaping the immune response, promoting either resolution or persistent inflammation depending on the signals they receive and the context of the tissue environment.

In contrast, erythrocytes (red blood cells) are not involved in the inflammatory process; instead, their primary function is to transport oxygen throughout the body. Platelets are primarily involved in blood clotting and the initial response to injury rather than in sustaining inflammation over time. Therefore, the dominance of macrophages in the chronic phase is key to understanding the dynamics of the immune response in the context of ongoing tissue damage and repair.