Impact of intraoperatively salvaged and washed blood on stimulated cytokine release in vitro.

Abstract

Intraoperative blood salvage and processing it with commercially available devices is a widespread standard procedure to reduce allogeneic blood transfusion in patients undergoing major orthopedic surgery. The aim of this study was to investigate the impact of such processed blood on the immune system by measuring pro- and anti-inflammatory cytokines. Salvaged blood from 20 patients undergoing hip arthroplasty was processed with a continuous autotransfusion system. One part of the processed blood was left without further treatment, one part was additionally leukoreduced, one part was irradiated, and one part was separated into its cellular and soluble fraction by centrifugation. Specimens from each part were mixed in vitro with venous blood from the patient in ratios of 3:1, 1:1, and 1:3 and incubated with endotoxin for 24 hours. Tumor necrosis factor (TNF)-α and interleukin (IL)-10 were measured in cell culture supernatants by enzyme-linked immunosorbent assay. All parts of the salvaged blood were without a significant influence on TNF-α release. In contrast, IL-10 was significantly increased, independently of the admixtured salvaged blood being plain, additionally irradiated, or additionally leukoreduced. This IL-10 increase was also found with the cellular fraction of the plain salvaged blood, whereas the soluble fraction had no influence on IL-10 release. Intraoperative salvaged blood is not immunologically inert. We observed a significant increase in the anti-inflammatory IL-10 response without affecting the proinflammatory TNF-α release. Neither leukofiltration nor gamma irradiation eliminated this effect that was limited only to the cellular fraction of the salvaged blood, suggesting red blood cells to be responsible for the observed immunomodulation.