How does a full blood count help to identify sepsis?

Differential: A complete blood count may be high or low in sepsis. We also look at a breakdown of the type of cells in the differential; a high number of neutrophils (pmns) can be suggestive of infection/sepsis but also bands (premature neutrophils) can be suggestive as well. The number of pmns or bands is expressed as a percentage of the total. If high sepsis/infection are possible.

Elevated white cells: Wbc count elevated and usually neutrophils count higher than normal also you may see what are bands in the peripheral smear. Other factors fever, listlessness, general ill feeling, sometimes low BP can be present.

High white cells?: I think you may mean high white blood cells? White blood cells are the infection fighting cells of the body. When there is an infection that causes sepsis, most of the time they are increased in number to help fight the infection. Thus, a high white blood cell count may be indicative of sepsis. But, there are a lot of things that can cause a high white blood cell count.