IMMUNOLOGY

Detailed explanation-1: -Phagocytosis. The ability of neutrophils to ingest and subsequently kill invading microbes is essential for the maintenance of host health. Neutrophils remove bacterial and fungal pathogens through a process known as phagocytosis.

Detailed explanation-2: -Neutrophils provide the first line of defense of the innate immune system by phagocytosing, killing, and digesting bacteria and fungi.

Detailed explanation-3: -While normally found in the blood stream, neutrophils migrate rapidly to sites of infection in tissue. The neutrophils trans-endothelial migration (TEM) process can occur by migration of neutrophils either directly through individual endothelial cells (the transcellular route) or between them (the paracellular route).

Detailed explanation-4: -Abstract. Neutrophils are an important component of the innate immune system and provide a front line of defense against bacterial infection. Although most bacteria are killed readily by neutrophils, some bacterial pathogens have the capacity to circumvent destruction by these host leukocytes.

Detailed explanation-5: -Mast cells can indirectly recruit neutrophils to a site of infection through the production of tumour necrosis factor (TNF)75 or a tryptase76, both of which promote chemokine production from tissue cells. Mast cells also directly recruit neutrophils through the production of leukotrienes such as LTB4 and LTC477.

Detailed explanation-6: -Phagocytosis is a process by which particles, microbes or fragments of dead cells are engulfed and internalized, usually by specific membrane receptors.

Detailed explanation-7: -At neutrophil concentrations of 3–6 × 106 per ml and in the presence of appropriate opsonins (e.g., IgG and complement), each neutrophil can ingest up to 100 Staphylococcus aureus or Escherichia coli in 30 min (6, 8).