Role of systemic T-cells and histopathological aspects after subcutaneous implantation of various carbon nanotubes in mice

We have evaluated the biological responses to four different types of carbon nanotubes (CNTs), by measuring CD4(+) and CD8(+) T-cells in peripheral blood, and by the histopathological study on tissues surrounding Subcutaneously implanted CNTs for up to 3 months. All mice survived, and no large changes in their weights were observed within our experimental period. After 1 week, only single-walled carbon nanotubes (SWNTs) activated major histocompatibility complex (MHC) class I pathway of antigen-antibody response system (higher CD4(+)/CD8(+) value), resulting in the appearance of an edematous aspect. After 2 weeks, significantly high values in CD4(+) and CD4(+)/CD8(+) without change in CD8(+) signified an activated MHC class II for all samples. It is worth noting that the toxicological response of CNTs was absolutely lower than that of asbestos. As a result, we envisaged that our result (relatively low toxicity of CNTs) will spur the mass-production, as well widespread application of CNTs in the near future. (c) 2005 Elsevier Ltd. All rights reserved.