The fluid exudate precedes cellular exudate. Bacterial breakdown products may act as chemo-tactic agents. All inflammatory cells are derived from bone marrow precursors. In the case of macrophages the immediate precursor is the blood monocyte. IL-1 contributes to the development of pyrexia.
Macrophages are able to phagocytose bacteria and cell debris.
Elastase and collagenase, amongst other proteolytic enzymes, are produced by macrophages. A neutrophil leucocytosis develops. CRP levels increase. CRP is an acute phase reactant. Plasma viscosity increases in the acute phase reaction.