Platelets (Thrombocytes)- Definition, Structure, Immunity, Functions

Platelets (Thrombocytes)

What are Platelets (Thrombocytes)? Platelets (Thrombocytes) Definition Platelets or thrombocytes are anucleated cells derived from the megakaryocytic cells in the bone marrow that, besides being one of the key players in maintaining hemostasis, are involved in developing non-hemostatic immune functions. Platelets the second most abundant cells in the blood circulation, with the concentration ranging between 150-400 × 109 /L. The …

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Monocytes- Definition, Structure, Immunity, Subsets, Functions


What are Monocytes? Definition of Monocytes Monocytes are cells of the immune system that represent immune effector cells with chemokine receptors and pathogen recognition receptors that circulate through blood or remain localized in lymphoid organs. These cells account for about 5% of the total circulating nucleated cells in human blood and have a half-life of three days. Monocytes are essential …

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Basophils- Definition, Structure, Immunity and Functions


What are Basophils? Definition of Basophils Basophils are nonphagocytic granulocytes that are the least common leukocytes occurring in the blood circulation and are critical to the immune response against parasites. Basophils are similar to eosinophils in that these are produced in response to parasitic infections; however, in the absence of parasitic infections, basophils are involved in allergy symptoms. Even though …

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Eosinophils- Definition, Structure, Immunity and Functions


What are Eosinophils? Definition of Eosinophils Eosinophils are motile phagocytic cells that play an important homeostatic role in providing defense against parasitic infections. Eosinophils are bone marrow-derived granulocytes that remain in the bloodstream for a shorter period of time and mostly reside in tissues. The functions of eosinophils are multifaceted, including antigen presentation, the release of peptides, lipids, and cytokine …

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Mast Cells- Definition, Structure, Immunity, Types, Functions

Mast Cells

What are Mast Cells? Definition of Mast Cells Mast cells are cells of the immune system of the hematopoietic lineage that remain widely distributed in vascularized tissues throughout the body. Mast cells, unlike other immune cells, do not remain in the blood but remain localized in mucosal and epithelial tissues throughout the body. These are among the first cells to …

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Dendritic Cells- Definition, Structure, Immunity, Types, Functions

Dendritic Cells

What are Dendritic Cells? Definition of Dendritic cells Dendritic cells are key antigen-presenting cells of the immune system that inform other effector immune cells to fight against invasive pathogens. These are also called professional antigen-presenting cells as these present antigens or parts of antigen to the receptors on different immune cells in order to elicit an immune response against them. …

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Natural Killer (NK) Cells- Definition, Structure, Immunity, Functions

Natural Killer (NK) Cells

What are Natural Killer (NK) Cells? Definition of NK Cells Natural killer (NK) cells are a group of innate lymphocyte cells with cytolytic activity against virus-infected cells and physiologically stressed cells like tumor cells. Initially, NK cells were described as larger granular lymphocytes with cytotoxic activity against tumor cells. However, these have since been recognized as a separated lineage of …

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