Final answer:
Macrophages are immune cells that perform phagocytosis, release cytokines, and stimulate inflammation to combat infection. They also facilitate chemotaxis by directing other immune cells to the infection site and may influence the number of white blood cells during an immune response.
Step-by-step explanation:
Macrophages and Their Role in the Immune Response
Macrophages are large white blood cells derived from monocytes that play a crucial role in the body's immune response. When there is tissue damage or infection, macrophages perform several functions: they release cytokines to recruit other immune cells, they move towards the site of infection (chemotaxis), and they engulf and digest pathogens through phagocytosis. The cytokines also stimulate inflammation, which leads to increased permeability of capillaries, allowing immune cells to reach the affected area more easily.
During an inflammatory response, neutrophils and monocytes pass through capillaries to reach the site of infection where monocytes mature into macrophages. The macrophages, along with neutrophils and dendritic cells, consume invading bacteria by phagocytosis, which is part of the body's nonspecific defense mechanism. Additionally, macrophages release chemical signals that may cause an increase in white blood cell count, which further strengthens the immune response.
An involvement in the increase of allergies and helminth infections is associated with a specific type of white blood cell called eosinophils, which work in conjunction with other immune cells and are particularly active in allergic responses and protection against parasitic worms.