During a blood test what did a white blood cell differential measure? Mostly high or low good?

Types of white cells. The differential looks at the different types of white blood cells (WBCs). The number given is a percentage of that type of WBC relative to the other types. There are a number of reasons to have a WBC test drawn, so the real answer depends upon the context of the test. If you are looking for infection, some types of cells may suggest viral (lymphocytes) versus bacterial infection (neutrophils).