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

Abstract

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.

Microdevice with an Integrated Clark-Type Oxygen Electrode for the Measurement of the Respiratory Activity of Cells

“…The antibacterial activity of neutrophils can be measured by measuring the change in the consumption of dissolved oxygen by active bacteria. 26,28 To check the applicability to this analysis, freeze-dried E. coli was reactivated and co-incubated with neutrophils. The antibacterial activity of neutrophils is influenced by water-immersion restraint stress.…”

“…Details of the procedures are described elsewhere. 28 All of the animal experiments were conducted according to the guidelines of the Institutional Review Board for the Care of Animal Subjects at the National Defense Medical College, Japan (permit no. 14055).…”

“…On the other hand, the existence of the oxygen-permeable membrane makes fabrication of devices challenging. Nevertheless, some devices have been developed − and their usefulness demonstrated in the measurements of respiratory activities of HeLa cells, breast cancer cells, rat skeletal muscle cells, , bovine oocytes, and others and the antibacterial activity of neutrophils using E. coli. , …”

“…Nevertheless, some devices have been developed 22−30 and their usefulness demonstrated in the measurements of respiratory activities of HeLa cells, 22 breast cancer cells, 30 rat skeletal muscle cells, 23,24 bovine oocytes, and others 27 and the antibacterial activity of neutrophils using E. coli. 26,28 Although the devices with integrated Clark-type oxygen electrodes demonstrate attractive performance and applications for laboratory experiments, some critical issues remain that prevent their widespread use. First is the storage and preparation for measurements particularly by nonspecialists of sensors.…”