MICROANATOMY

Detailed explanation-1: -Once inflammation has begun, the first cells attracted to the site of infection are generally neutrophils. They are followed by monocytes, which differentiate into more tissue macrophages. In the later stages of inflammation, other leukocytes such as eosinophils and lymphocytes also enter the infected site.

Detailed explanation-2: -Monocytes are phagocytic leukocytes of the blood that, in conjunction with tissue macrophages and neutrophils, are important cells involved in first-line defense against pathogenic organisms or foreign cells (Fig. 19.4).

Detailed explanation-3: -The innate immune system is the body’s first line of defense against germs entering the body. It responds in the same way to all germs and foreign substances, which is why it is sometimes referred to as the “nonspecific” immune system.

Detailed explanation-4: -Nonspecific leukocytes include monocytes, macrophages, neutrophils, eosinophils, and basophils. These leukocytes are part of the second line of defense.

Detailed explanation-5: -Monocytes have a direct antimicrobial role at sites of infection and can also, particularly during pulmonary or dermal infections, carry microbial antigens to local lymph nodes, where they can either transfer antigens to classical dendritic cells (DCs)111 or differentiate into monocyte-derived DCs.