Heat sterilized PD-fluids impair growth and inflammatory responses of cultured cell lines and human leukocytes.

We have recently demonstrated that commercial PD-fluids inhibit the growth of a cultured mouse fibroblast cell line. Toxic substances produced during heat sterilization were believed to be the probable cause of the growth inhibition. The aim of the present study was to investigate if heat sterilized PD-fluids affect other cell types and other cellular functions than the growth of fibroblasts. The effect of three commercially and one laboratory made PD-fluid on cell growth of a mouse macrophage cell line (RAW) and a human neuroblastoma cell line (SH-SY5Y) was examined. The influence on stimulated release of tumour necrosis factor alpha (TNF alpha) from the macrophage cell line and stimulated superoxide generation from freshly prepared human leukocytes were also investigated. Compared to the filter sterilized PD-fluid, we found that heat treated PD-fluids significantly inhibited the growth of the two cell lines and impaired the stimulated release of TNF alpha and superoxide radicals. These results demonstrate that heat sterilization of PD-fluids produces substances that are cytotoxic regardless of the cell species, the cell type or the cell function tested.

Toxicity of peritoneal dialysis fluids on cultured fibroblasts, L-929.

Peritoneal dialysis (PD) fluids are known to suppress the reactions of inflammatory cells in vitro. PD-fluids have also been shown to have cytotoxic influence on mesothelial cells. The combinations of these factors may have a detrimental effect on the peritoneum or may impair cellular defence against bacterial peritonitis. Some authors have discussed the relevance of heat sterilization to both so-called peritoneal side-effects and to chemical decomposition of fluids. Four commercial PD-fluids and one laboratory-made PD-fluid were tested for cytotoxicity on a cultured fibroblast cell line, L-929. Cytotoxicity was determined as an inhibition of cell growth by quantification of total protein. The laboratory-made PD-fluid was sterilized either by filtration or by filtration and heat. The commercial and the heat-sterilized laboratory made PD-fluids caused significant inhibition of cell growth (53 to 76%) in contrast to saline and the filter-sterilized laboratory-made PD-fluid. Since the pH values of all the testsolutions were neutral, low pH was not the cause of toxicity. Our results regarding the L-929 cells indicate that the cytotoxicity of PD-fluids is of a general nature. Furthermore, the results indicate that the heat sterilization process might be partially responsible for causing toxicity in PD-fluids.