(The Best Years in Life) Low white blood cell counts are indicative of a suppressed immune system and can have many causes. Emotional state and stress, an unhealthy diet and lifestyle, and nutritional intake can all cause lower immune system response and low white blood cell counts. Low immunity can also be caused by a number of health conditions, by surgical or medical treatments and by the natural aging process. Whatever the cause, low immunity and low white blood cell counts prevent the body from being able to have an optimum response to infections and illness. Here are some things which can help prevent low immunity and keep white blood cell counts high: Read More.