A web service differs from a web site in that a web service provides information consumable by software rather than humans. As a result, we are usually talking about exposed JSON, XML, or SOAP services. Web services are a key component in mashups.
Leukopenia is a shortage of white blood cells in the system, which can be caused by anemia, menorrhagia, etc. A low white blood cell count, or leukopenia will have a direct effect on your body's immune system. White blood cells are used to fight off infections within the blood stream. Without an adequate number of white blood cells your body will have trouble ridding itself of bacteria or viral matter which can cause disease.
Circulating lymphocytes are sometimes trapped in the lymph nodes or the spleen, causing a low lymphocyte count. Their numbers also are affected by the same factors that influence the total white blood count, such as autoimmune disorders (diseases that cause the body's immune system to attack normal body cells), infections, some cancers, and cancer treatments such as radiation and chemotherapy.