Macrophages: bodyguards of the joints.
Macrophages are cells specialized in the detection, phagocytosis and destruction of bacteria and other harmful organisms. In addition, they can present antigens to cells and initiate the inflammatory process by releasing molecules (called cytokines), which activate other cells.
We highlight monocyte-derived macrophages, which actively contribute to joint inflammation, and epithelial-type macrophages that restrain the inflammatory response by providing protection through intra-articular tight junctions. This functional diversification among synovial macrophages has important implications for the overall role of this cell type in inflammatory processes. Macrophages thus exist in several subsets, some of which are proinflammatory, while others are anti-inflammatory and aid in tissue repair. This balance of inflammation and anti-inflammation makes them, among other things, the guardians of the joints.
Neutrophils: the recruiters.
They are very important as mediators of inflammation. On the one hand, neutrophils release different substances that contribute to the inflammatory reaction and the recruitment of other immune system cells to the site of infection. They are the most common type of white blood cell. They go to the site of infection and release substances called enzymes to fight invading bacteria or viruses.
Eosinophils: diplomats in the face of hypersensitivity.
They have different functions, of which we highlight:
Defense against parasitic infections. Defense against intracellular bacteria. Modulation of immediate hypersensitivity reactions.
Basophils: special operating group.
Basophils are found in the blood and when they are needed in parasitic infections, they come immediately and settle in the tissues. There, they unfold and release the contents of their granules, small compartments containing substances that facilitate the initiation of the inflammatory process (e.g. histamine) and the elimination of the pathogen.