Hematologic response to acute inflammation: the band neutrophil revisited

The value of the routine visual (manual) 100-cell differential leukocyte count (DLC) as a screening test in asymptomatic individuals or in patients on admission without suspected distributional or morphologic abnormalities has been challenged in the medical literature. More recently, the usefulness of an increase in the band neutrophils or a "left-shift" in the manual DLC has also been in question. This article discusses the largest sources of error in the routine DLC, namely, cell-identification errors, distributional errors, and statistical sampling errors. The latest flow cytometric, cytochemical, automated leukocyte differential counters offer a viable, reliable alternative to the highly imprecise 100-cell DLC. Studies have shown that these newer instruments are sensitive in detecting the hematologic response to acute inflammation or infection and have the advantage of vastly increased precision and therefore of improved reliability of the differential leukocyte count.