The immune System

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The immune system is the body’s defence mechanism against pathogens. This system comprises of many cells that work together to protect the body from foreign invaders such as bacteria, viruses, parasites as well as tumours. The immune system is divided into two primitive forms, the innate and adaptive systems. The roles for both types are vital in the immune system; the innate is the rapid, non-specific primary response against any foreign material the body encounters, whereas the adaptive system is a secondary response and a more specific line of defence. The adaptive as well as the innate responses initiation are hugely associated with each other. The innate response consists of many components; these include mechanical, chemical, humoral as well as cellular barriers. The main line of defence in the innate system is the cellular component; there are different types of cells involved, however, the most critical cell of all other different immune cells is called a macrophage. Macrophages are a phagocytic cells originated from monocytes, a form of blood leukocytes. Monocytes are made by bone marrow in the myeloid lineage through committed haematopoietic stem cells in a process called haematopoiesis. Macrophages carry out indispensable roles in the immune system; they are involved in both of innate and adaptive responses. Thus, macrophages are always referred as the cells that ‘bridge’ the innate and adaptive systems. This essay will discuss the functions and activities of the macrophage that make it the most important cell in the immune system. Monocytes are the precursors for macrophages; these monocytes migrate and differentiate into tissue macrophages once they encounter an infection. Macrophages are distributed around the w... ... middle of paper ..., anti-parasitic as well as anti-tumor activities. Macrophages play an important role in the defence against tumours. This defence is achieved by the rapid response, the production and secretion of various cytokines that target the activation of dendretic cells (DC) and natural killer cells (NK). INF-y is the main cytokine that drive NK to stop the progression of tumour, and NK cells to activate the T cells to respond to the danger (Lamagna et al. 2006). Tissue repair is critical for the body in order to regenerate the destruction of tissue during the inflammatory response. Macrophages are crucial for the resolution of the tissue. This is done by the secretion of the cytokine GM-CSF which is a colony stimulating factor; it proliferates and results in tissue healing. Also, macrophages secrete collagenase and elastase enzymes that promote tissue repair.
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