On‐site rapid detection of antibacterial activity of neutrophils using freeze‐dried bacteria

Impaired neutrophil functions, and in particular their antibacterial activity, are known to reflect the immunocompromised condition of the host. To investigate the potential for prompt on‐site measurement of this condition, we analysed the antibacterial activity of murine neutrophils by measuring the change in oxygen consumption in a 10 μl sample solution in which bacteria and neutrophils were co‐incubated. A critical point was the use of freeze‐dried Escherichia coli ( E. coli ), which remarkably facilitated handling because of its ability to be stored at room temperature for extended periods and the ease in which its respiratory activity could be re‐established. This therefore allowed the antibacterial activity of murine neutrophils to be measured following their co‐incubation with E. coli . Indeed, we successfully detected a reduction in the antibacterial activity of murine neutrophils in mice subjected to water‐immersion restraint stress.