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.
With all that in mind, if you and your doctor determine that your white blood cell count is lower than it should be, that is cause for concern. Because a low white blood cell count cannot, in and of itself, be used to diagnose a specific disease or disorder, you'll likely need more testing to further assess your condition. Underlying causes for a low white blood cell count can range from benign disorders, such as vitamin deficiencies, to more serious blood diseases, such as leukemia or lymphoma.