Preserved solid lipid nanoparticles (SLN) at low concentrations do cause neither direct nor indirect cytotoxic effects in peritoneal macrophages

In order to investigate the interaction of preserved solid lipid nanopartic les (SLN) with murine peritoneal macrophages (M empty set), cytotoxicity an d proinflammatory effects of two different solid lipid nanoparticles (SLN) preparations consisting of either compritol (CO) or cetyl palmitate (CP) pr eserved with thiomersal were analyzed. Concentration-dependent cytotoxic ef fects were observed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tet razolium bromide (MTT) assay. Secretion of interleukin-6 by M empty set fol lowing incubation with CO and CP SLN did not differ from secretion by untre ated cells; proinflammatory cytokines interleukin-12 and tumor-necrosis-fac tor-alpha as further indicators of immunomodulatory effects were not detect able. These findings paralleled our previous findings that unpreserved CO a nd CP SLN did not induce immunomodulatory effects but cytotoxicity at highe r concentrations. There were no synergistic cytotoxic effects of preservati ve and SLN. Thus, preservation of SLN using thiomersal does not appear to c ause increased cytotoxicity and immunomodulatory effects following incubati on with M empty set. (C) 2000 Elsevier Science B.V. All rights reserved.