Automated cytochemical staining and inflammation. Further assessment of the "left shift"

Automated differential leukocyte counting devices identify neutrophils on the basis of size and peroxidase staining. Since no analysis of neutrophil subpopulations is provided, detection of the "left shift" as reflected by increased numbers of band neutrophils is not possible. It has been suggested that samples with increased numbers of high peroxidase neutrophils (HPX) correspond to conventional samples with increased band neutrophils. Using blood samples enriched by 700% in their band neutrophil concentration, no significant change in the number of HPX cells or mean peroxidase content was detected. Examination of Wright-stained smears with increased concentrations of HPX cells invariably revealed toxic neutrophils not seen in controls. The authors concluded that increases in HPX cells do reflect inflammation but that such increases correlate with the presence of toxic neutrophils and not band neutrophils.