A leukocyte is also referred as White Blood Cells (WBC’s). A leukocyte is derived from Greek word ‘leuco’ meaning white. Leukocytes are part of immune system cells which fight against pathogenic entry of infectious microorganisms like bacteria and viruses. These cells are being derived from multipotent cell referred as hematopoietic stem cells. Hematopoietic stem cells are also termed as bone marrow cells. White Blood Cells can be seen throughout the lymphatic system and blood. Presence of white blood cell count indicates the presence of foreign organisms. 1 percent of human blood contains leukocytes. For instance, normal individual contains 4 * 109 – 1.1 * 1010 white blood cells in one liter of blood. When the number of white blood cells increases above the upper threshold limit it results in leukocytosis. Similarly decrease in number of white blood cells below the lower threshold limit it results in leucopenia. For instance decrease in neutrophil count is referred as neutropenia.
Physical Properties of Leukocytes:
Following are physical properties of leukocytes.
Types of Leukocytes:
Based on the presence of granules, leukocytes are categorized as follows.