An extended leukocyte differential count (16 types of circulating leukocytes) using the cytodiff flow cytometric system can provide informations for the discrimination of sepsis severity and prediction of outcome in sepsis patients.

Background: The Beckman Coulter CytoDiff flow cytometric system (Beckman Coulter, Miami, FL, USA) was recently developed for performing leukocyte differential counts in up to 16 leukocyte subpopulations. We compared these leukocyte subpopulation levels among patients with three stages of sepsis (uncomplicated sepsis, severe sepsis, septic shock), especially focused on the discrimination of complicated sepsis from uncomplicated sepsis.
Methods: We examined a total of 181 samples with sepsis who were admitted to the surgical intensive care unit. In addition, we examined samples obtained from 60 normal healthy volunteers. Both the proportions and absolute numbers of each cell type in the four groups were obtained using the CytoDiff flow cytometric system and compared.
Results: Mature neutrophils and immature granulocytes failed to discriminate patients with complicated sepsis from those with uncomplicated sepsis although their absolute numbers were increased compared with normal controls. In contrast, almost all lymphocyte subpopulations and CD16(-) monocytes decreased significantly in patients with complicated sepsis compared with uncomplicated sepsis. Among them, only B lymphocytes showed independent ability to discriminate two groups. Both B lymphocytes and CD16(-) monocytes possessed a significant adverse prognostic impact on overall survival when their absolute numbers decreased. Conclusions: Almost all lymphocyte subpopulations and CD16(-) monocytes decrease in size with increasing sepsis severity. Among them, only B lymphocytes showed independent ability to discriminate patients with complicated sepsis from those with uncomplicated sepsis. Both B lymphocytes and CD16(-) monocytes show a significant adverse prognostic impact on overall survival outcomes in sepsis patients when their absolute numbers are decreased. © 2013 Clinical Cytometry Society.