Macrophages are found in -

Ans. is 'c' i.e., Late phase of inflammation Cells in acute inflammation Neutrophils predominate in the early phase of inflammation (the phase occuring within 24 hrs) whereas macrophages enter the area in late phase of inflammation ie. after 24-48 hrs. Neutrophils remain predominant cells for upto 72 hrs, after which the macrophages take over as predominant cell. Lymphocytes and plasma cells are also seen along with macrophages in the acute inflammatory response. Mast cells may also involve in acute inflammation. There are exceptions to this pattern of cellular reaction :- Pseudomonas infection - Neutrophils predominate over 2 to 4 days. Viral infection --> Lymphocytes are the first cells to arrive. In some hypersensitivity reactions --4 Eosinophils predominate. Why neutrophils are replaced by macrophages ? Neutrophils can not regenerate their lysosomal enzymes, so these cells are not capable of sustained activity. On the other hand macrophages can regenerate their lysosomal enzymes and are capable of sustained activity. So, macrophages become the predominant cells after 48-72 hrs to sustaine inflammation. Cells in Chronic inflammation The macrophage is the dominant cellular player in chronic inflammation. Other cells present in chronic inflammation include lymphocytes, plasma cells, Eosinophils, mast cells. Although neutrophils are characteristic of acute inflammation, many forms of chronic inflammation continue to slow large number of neutrophils e.g., in chronic bacterial osteomyelitis, and in the chronic damage induced in lungs by smoking & irritant stimuli. Cell of acute inflammation Neutrophils (major cells) Macrophage Lymphocyte Plasma cell Mast cells o Eosinophils (in some hyper sensitivity reactions) Cells of chronic inflammation o Macrophages (major cells) o Lymphocyte o Plasma cell o Eosinophils o Mast cells