OBJECTIVETo assess the genetic damage of human B lymphocyte cell line induced by 14 nm and 280 nm carbon black (CB) particles with micronucleus assay (CBMN), comet assay and hprt gene mutation test in vitro.

METHODSThe genetic damage of human B lymphocyte cells exposed to 14 nm and 280 nm CB particles at the doses of 0, 128, 256, 384 and 512 microg/ml for 24 h and 48 h was detected using above three genotoxic assays. Micronucleus (MN) assay, comet assay, hprt gene mutation test were used to detect the genetic damage of human B lymphocyte cells induced by CB. Micronucleus rate (MNR), micronucleated cell rate (MCR), nuclear buds (Buds), nucleoplasmic bridges (NPBs), nuclear division index (NDI) and numbers of apoptotic cells served as indexes of CBMN assay; the percentage of DNA in the tail (% tail DNA) and the olive tail moment (OTM) were used as DNA damage indicators of comet assay; the hprt gene mutation frequency (Mf-hprt) served as the index of hprt gene mutation test.

RESULTSThe % tail DNA, OTM in 14 nm CB group at the doses of 384 and 512 microg/ml for 48 h were 8.23% +/- 0.19%, 11.23% +/- 0.42% and 3.72 +/- 0.08, 4.90 +/- 0.18, respectively, which were significantly higher than those in control (5.10% +/- 0.08% and 2.22 +/- 0.03) (P < 0.01). The apoptotic cell rates in 14 nm CB group at the doses of 384 and 512 microg/ml for 48 h were 4.67 +/- 0.33 and 5.33 +/- 0.33, respectively, which were significantly higher than in control (0.00 +/- 0.00) (P < 0.05). The results of Mf-hprt were negative.

CONCLUSIONThe genetic damage of human B lymphocyte cells exposed to 14 nm CB particles for 48 h could be detected. But the similar effects didn't appear in 280 nm CB group.