Impaired oxygen consumption activity of neutrophils by inhibitor(s) in burn sera

To reflect the in vivo condition in an in vitro assay system, a whole blood assay technique (modified CO-micromethod) (Nakamura et al) was used for detection of oxygen consumption in peripheral blood that had been diluted with auto-logous plasma to bring the final concentration of leukocytes to 2.5× 10⁵/0.25 ml. Dextran-separaled leukocytes in plasma and serum (1,600 × g, 30 minutes) were also used for analytical purposes. Burn patients’ leukocytes showed an impaired rate of oxygen consumption during phagocytosis of opsonified zymosan in whole blood between 7 and 15 days postburn (n = 70; 19 cases). The separated burn leukocytes showed the lowest rate in autologous serum and gave the highest rate of activity in Hepes-saline buffer. On the contrary, normal leukocytes constantly showed lowest activity in buffer. Preincu-bation (30 minutes, 37 C) of normal leukocytes in burn serum (cross-matched) resulted in an impaired rate of oxygen consumption. This decrease was not found on similar incubations in matched, normal homologous serum. These results indicate that burn serum (obtained during the 7- to 15-day poslburn interval) contains phagocyte-inhibitory factor(s). These results suggest strongly that the burn serum or plasma may contain substance(s) responsible for a major portion of the observed inhibition of the rate of oxygen consumption.