Tumor necrosis factor (TNFalpha) production by rat peritoneal macrophages is not polyacrylate surface-chemistry...

Polyacrylate films in the absence of added endotoxin caused rat peritoneal macrophages to secrete a small amount of TNFalpha. There was little difference, if any, among the materials, which included various co- or ter-polymers of hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid, methyl methacrylate, and butyl methacrylate. The materials were surface characterized and endotoxin cleaned prior to testing. Equivalent endotoxin levels associated with the material were <0.03 EU/mL for all materials but two; for polyHEMA, the most contaminated material, it was 0.23 EU/mL. Films of the materials were incubated with freshly isolated rat peritoneal macrophages for 6 to 24 h before the TNFalpha levels in the supernatant were analyzed for biological activity, using L929 cells as a target. When endotoxin was added, far greater quantities of TNFalpha were generated at 24 h compared to 6 h, but still there was little effect with regard to material chemistry. Such an in vitro assay proved not to be useful for the screening of potential microencapsulation materials for peritoneal biocompatibility.