The primary function of these mononuclear cells is to phagocytose invading organisms, dead cells, immune complexes, and antigens. To do this, these cells are equipped with powerful lysosomal granules containing acid hydrolases and other degrading enzymes. Macrophages need activation to carry out these functions. These include cytokines, which can bind to IgG: Fc receptors or most importantly (as we shall see later) receptors for bacterial polysaccharides. In addition, they can be activated by soluble inflammatory products such as C5a. In turn, the macrophages can release monokines, such as TNF or IL-1, which increase the inflammation in inflamed tissues.