Leucocytes (white blood cells) are outnumbered by the red blood cells 600 to 1. These cells are spherical in shape and slightly larger than red blood cells. There are five types of leukocytes. Three of the five have a granular appearance. These are the neutrophils, eosinophils, and the basophiles. The other two, the lymphocytes and monocytes, have smooth, non-granular bodies. The main function of the leukocytes is to provide a defence against 'foreign' material (infectious agents, foreign bodies, abnormal proteins). In the presence of a foreign material, basophiles and some lymphocytes release chemicals that cause inflammation, trapping the invader. The other leukocytes then take the foreign material into their own bodies and digest them. This process of digestion is called phagocytosis. The cells that digest microbes are called phagocytes. The most numerous of the phagocytes are the neutrophils.
In addition to neutrophils, eosinophils, and monocytes, the body has other phagocytes that are not white blood cells. They are classed as reticuloendothelial cells, a type of connective tissue cells. Lymphocytes are the smallest white blood cells and are a part of the immune mechanism. They form antibodies against disease. When microbes invade the body, lymphocytes begin to multiply and they become transformed plasma cells. Each microbe stimulates only one type of lymphocyte to multiply and form one type of plasmacell. The type of plasmacell formed is the type that can make a specific antibody to destroy the particular microbe that has invaded the body. Red bonemarrow continually produces white blood cells, except lymphocytes and monocytes, and keeps a reserve ready in case of need. Lymphocytes and monocytes are produced by lymphatic tissue located in the lymph nodes and spleen. When a parasite or virus invades and begins to colonize, the reserves of white blood cells are released and the manufacturing of large quantities of the appropriate white cells begins. It is this increased production that causes fever.
Because white blood cells are supposedly specific for various illnesses, their count can supposedly assist doctors diagnose patients. However, as has been shown by researchers at Perth, Australia (The Perth Group), white bloodcell counts can also be misleading as many conditions cause very similar counts, leading some researchers to question the emphasis currently placed on white bloodcell counts in diagnosis. Research Leucocytes
Leucocytosis is the name given to a condition of the blood in which the leucocytes or white corpuscles in the bloodplasma are increased in number. These leucocytes are minute protoplasmic cells, which have the power of movement and can pass out of the smallest capillary blood vessels into the surrounding tissues. They act as scavengers, and play an important part in the destruction and removal of bacteria in the body, a process known as phagocytosis.
The leucocytes are of different types, and normal blood contains a fairly constant proportion of each type. In infection or inflammation the leucocytes become greatly increased in number; the leucocytes which are killed in the attack on the bacteria form pus. In certain blood diseases, of which leukaemia is the best example, the increase is also often enormous, even reaching to 80,000 and 100,000 white corpuscles in a cubic millimetre of blood which normally contains only from 5,000 to 6,000. The symptoms of this disease are very similar to those of anaemia, and the diagnosis is confirmed by microscopic examination of the blood. The leukaemias are accompanied by swelling of the glands but this also occurs in other diseases.
A small increase of the white corpuscles is found in such a great number of the more common diseases that an examination of the blood is often made as a routine measure. In many cases, for instance, of appendicitis, the white corpuscles increase to from 15,000 to 20,000 per cubic millimetre; in pneumonia they also increase sometimes to 40,000 per cubic millimetre. In other more common diseases such as tonsilitis or sore throat, erysipelas, in smallpox, and inflammatory diseases such as septicaemia, boils, bone diseases and pyaemia, a greater or less increase is always found. In other diseases absence of an increase often enables the right diagnosis to be made, since in typhoid fever (which might in the early stages be mistaken for appendicitis) there would be no increase in the early stage of the disease, but it would probably be marked in the latter stages. In whooping-cough a marked leucocytosis occurs, which may confirm a doubtful diagnosis. Research Leucocytosis
Leukaemia is an acute or chronic disease characterised by a gross proliferation of leucocytes, which crowd into the bonemarrow, spleen, lymph nodes, etc., and suppress the blood-forming apparatus. Research Leukaemia
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Leucocytes
