Macrophages seek out foreign invaders in the , while neutrophils, at least initially are on patrol in the .

Macrophages seek out foreign invaders in the TISSUES, while neutrophils, at least initially are on patrol in the BLOODSTREAM.

Explanation:

Macrophages are one type of white globules that intervene to defend the organism against strange substances and pathogen agents. These cells are the principal actors in the immune response. Macrophages have several functions. They are the principal phagocytes of tissues, capable of recognizing different strange molecules that penetrate the organism, such as bacterias, parasites and, viruses. Macrophages phagocyte these substances and eliminate them, a process known as phagocytosis. When macrophages are active they release cytokines that favor inflammation response, which is used to neutralize the pathogen agent and the migration of other immune cells to the affected area. Macrophages also have the capability of inducing an adaptative immune response.  

Neutrophil: Phagocytic Leucocytes polymorphonuclear found in the peripheric blood. Compose the first defense line against bacterial and fungal infections. Product of the medulla and transported to the blood. They are the first to arrive at the affected tissue, followed by lymphocytes and macrophages.    

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