An increase in the number of leukocytes over the upper limits is called leukocytosis, and a decrease below the lower limit is called leukopenia.
From the en.wikipedia.org
Leukocytosis is often seen during inflammation induced by infection, where it results in a large increase in the amount of leukocytes in the blood, especially immature cells.
From the en.wikipedia.org
More examples
An abnormal increase in the number of white blood cells in the blood as a result of infection (as in leukemia)
Leukocytosis is a raised white blood cell count (the leukocyte count) above the normal range in the blood. This increase in leukocytes (primarily neutrophils) is usually accompanied by a "left shift" in the ratio of immature to mature neutrophils. ...
A condition characterized by an abnormally high total number of circulating leukocytes.