Two groups of cells are moved along the circulating blood. One, the red blood cells. is involved in the transfer of oxygen to the tissues and is responsible for the red color of blood: the other, the white blood cells, takes part in the body’s defense, as in inflammation. There are several groups of white blood cells-lymphocytes, plasma cells. polymorphonuclear leukocytes-each with different properties and making different contributions to defense. The polvmorphonuclear leukocytes, for example. are involved in acute inflammation against bacteria; thus they are the major cells found in pus.
Enumeration of blood cells, known as a blood count. is a routine and basic examination in medicine. A complete blood count may call for several more hits of information:
1. An estimate of hemoglobin (the essential component of the red blood cell).
2. A differential white blood cell count, in which the white blood cells are stained and the different kinds counted.
3. Occasionally, a platelet count-a count of the tiny_ cellular fragments, or platelets, which play an important role in blood-clotting.
The blood count is an important diagnostic clue. In anemia both the red blood cell count and the hemoglobin count fall. In leukemia, the white blood cells are abnormal and often very high in number. The white blood cell count is generally high when there is infection due to bacteria, but barely elevated appropriate chemical procedures. The most important one which is now commercially available is gamma globulin. It is formed by the lymphocyte-plasma cell group of the white blood cells, and is part of the body’s chemical defenses against infection.
The disease-fighting globulins are sometimes referred to as antibodies; without antibodies it would be impossible to develop immunity, and we would be fighting the same disease battles over and over again. As it is, one successful battle may result in the production of enough antibodies to protect the individual against that organism for the rest of his life. For this reason, an adult who has had measles or hepatitis can be exposed to a child with the disease and not reacquire it. In fact, such antibodies are produced even when the disease is nipped in the bud; thus a person may be exposed to the viruses of polio, hepatitis, or mumps and overcome them without the characteristic signs of the disease, be it the paralysis of polio or the jaundice of hepatitis. These brief battles may produce relatively few symptoms beyond fever and grippal sensations, often cannot be diagnosed, but nonetheless produce immunity. Hence commercially obtained gamma globulin made from a pool derived from many individuals is a storehouse filled with all sorts of specialized weapons capable of fighting a variety of infective processes. And sometimes even low in many infections due to viruses. ‘The white cells increase as an infection worsens and decrease as it subsides. In allergic disorders a special kind of white cell known as the eosinophil may be considerably increased. Changes in white cells occur in infectious mononucleosis. Low counts for all types of cells may be found in certain disorders of the spleen and bone marrow.