Single-walled carbon nanotubes impair human macrophage engulfment of apoptotic cell corpses

Abstract

Single-walled carbon nanotubes (SWCNT) are being produced in increasing quantities and the application of these materials in a large number of new technologies and consumer products necessitates studies of their potential impact on human health and the environment. To determine whether SWCNT affect viability or function of macrophages, important components of the innate immune system, we performed in vitro studies using primary human monocyte-derived macrophages (HMDM). Our findings show that SWCNT with a low content of metal impurities do not exert direct cytotoxic effects on HMDM. However, SWCNT suppressed chemotaxis of primary human monocytes in a standard chemotaxis assay. Moreover, macrophage engulfment of apoptotic target cells was significantly impaired following pre-incubation of HMDM with SWCNT at non-cytotoxic concentrations. These results are in line with previous studies showing that ultrafine carbon particles and carbon nanotubes may impair alveolar macrophage ingestion of microorganisms, and suggest that tissue homeostasis may be compromised by SWCNT due to suppressive effects on macrophages.

Keywords::

• Single-walled carbon nanotubes
• human monocyte-derived macrophages
• phagocytosis
• chemotaxis
• cytotoxicity

Declaration of interest: The current work was presented, in part, at the 11th International Inhalation Symposium (INIS) on Benefits and Risks of Inhaled Engineered Nanoparticles, June 11–14, 2008, Hannover, Germany. Supported by the Swedish Research Council, NIOSH OH008282, NIH HL70755, NORA 927000Y, and the 7th Framework Programme of the European Commission (NANOMMUNE). The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.