In Vitro Study of Mutagenesis Induced by Crocidolite-Exposed Alveolar Macrophages NR8383 in Cocultured Big Blue Rat2 Embryonic Fibroblasts

Table 3

Cytotoxicity and mutation frequencies in Big Blue cells following various treatments in mono- or coculture with NR8383 cells.

Treatment and culture condition		% cell mortality (Mean $\pm$ SD)	PFU per assay	Mutant plaques	MF ($\times$10^−5)	Group average MF ($\times$10^−5$\pm$ SD)
ENU, monoculture, 30 min	Control	1.2 $\pm$ 0.5	375000	32	8.5	9.6 $\pm$ 1.0
			350000	36	10.3
			455000	46	10.1
	100 $\mu$g/mL	2.3 $\pm$ 1.4	285000	133	46.7	41.8 $\pm$ 8.7*
			553333	176	31.8
			338330	159	47.0
	500 $\mu$g/mL	2.2 $\pm$ 0.5	223000	208	93.3	83.3 $\pm$ 9.8*
			368330	306	83.1
			203666	150	73.6
Crocidolite separated coculture, 72 h	Control	4.1 $\pm$ 1.9 (BB); 5.4 $\pm$2.3 (NR)	423334	47	11.1	12.9 $\pm$ 1.6
			860333	102	11.9
			868333	122	14.0
			566667	79	13.9
			675000	79	11.7
			573333	86	15.0
	3 $\mu$g/cm^2	5.8 $\pm$ 2.0 (BB); 7.9 $\pm$2.0 (NR)	349000	25	7.2	8.7 $\pm$ 1.7
			477333	41	8.6
			506166	53	10.5
	15 $\mu$g/cm^2	3.6 $\pm$ 1.8 (BB); 19.6 $\pm$1.3* (NR)	1090000	127	11.7	13.2 $\pm$ 2.2
			786667	77	9.8
			445000	70	15.7
			723333	104	14.4
			567667	82	14.4
			616667	81	13.1
Crocidolite, mixed coculture, 24 h	Control	8.2 $\pm$ 0.9	303350	63	20.8	19.0 $\pm$ 2.3
			303350	57	18.8
			301650	68	22.5
			460000	79	17.2
			501650	83	16.5
			388350	71	18.3
	10 $\mu$g/cm^2	15.0 $\pm$ 1.4*	246650	43	17.4	18.5 $\pm$ 4.4
			246650	63	25.5
			331650	71	21.4
			475333	61	12.8
			692333	122	17.6
			323350	52	16.1
Zymosan, mixed coculture, 3 h	Control	7.1 $\pm$ 2.0	468333	69	14.7	13.0 $\pm$ 1.5
			248000	30	12.1
			593333	72	12.1
	15 $\mu$g/cm^2	6.4 $\pm$ 0.8	525000	82	15.6	18.3 $\pm$ 2.9*
			656667	118	18.0
			393334	84	21.4
	30 $\mu$g/cm^2	7.0 $\pm$ 0.9	471667	83	17.6	17.4 $\pm$ 1.4*
			833334	156	18.7
			600000	96	16.0
	60 $\mu$g/cm^2	7.7 $\pm$ 1.8	465000	134	28.8	30.8 $\pm$ 7.0*
			574167	144	25.1
			513333	198	38.6

PFU: plaque forming unit; MF: mutant frequency; BB: Big Blue; NN: NR8383; *Statistically different from control values ($P<.05$).