When white blood cells are examined, they are evaluated based on the total number of WBCs in one cubic millimeter of venous blood and by the percentage of each type of cell (called leukocyte). An overall low WBC is indicative of overwhelming infection, dietary deficiencies, bone marrow failure and autoimmune disease. An increase in the amount of one leukocyte will mean a decrease in another, and indicate a certain pathology or group of pathologies.
The major function of WBCs is to fight infection and react against foreign bodies. Five types of WBCs are easily identified on a blood smear. In order of most abundant to least these cells are; neutrophils, lymphocytes, monocytes, eosinophils and basophils.
Interfering Factors That Can Cause a False Count
There are several factors that can cause the WBC count to be higher or lower than expected. If these factors are not considered a false diagnosis could be made. Eating, physical activity and stress may cause an increase in WBC. In addition a woman in her final month of pregnancy tends to have higher levels.
Your WBC count will be lower in the morning and higher in the late afternoon and evening. It also tends to be age-related. Newborns and infants tend to have higher WBC counts than adults. The elderly often have such a low count that they do not even respond to infection.
Certain drugs can interfere with an accurate count as well. Aspirin, epinephrine, heparin, quinine, steroids and chloroform will increase levels. Antibiotics, antihistamines, antithyroid drugs, barbiturates and diuretics will decease levels.
Neutrophils are the most common type of leukocyte. Their primary function is to kill and digest bacteria. In an acute bacterial infection or trauma more neutrophils will be made.
Low neutrophil levels can indicate an overwhelming bacterial infection, anemia, viral infection or Addison's disease. If you have a low neutrophil count, you are said to have neutropenia.
Lymphocytes are divided into two types: T-cells and B-cells. T-cells are involved with cellular-type immune reactions. B-cells are a part of what is called humoral immunity, which involves production of antibodies.
A low lymphocyte level is indicative of leukemia, sepsis and immunodeficiency diseases such as lupus and late-stage HIV infection.
Monocytes are cells that are capable of fighting bacteria. The are very similar to neutrophils in the way they function, but can be produced a lot quicker and spend longer in circulation. Normally the only reason for low monocyte levels is as a result of drug therapy, especially with the use of prednisone.
Low Eosinophils and Basophils
Both of these cells are involved in allergic reactions and some parasitic infections. Neither cell responds in any way to bacterial or viral infection. A low eosinophil level is a reaction to increased adrenosteriod production. A low basophil level can be the result of an acute allergic reaction, hyperthryoidism or stress.