TABLE 3.

TEM quantification, by direct counts, of the number of mitochondria found in contact with phagosomes containing L. pneumophila or differently coated beads, in U937-derived macrophages at 3 h postinoculation

Phagosome content	Events scoreda
	No. of cells observed	No. of phagosomes (+/-)	Total no. of phagosomes	P value 1	Total MT/total no. of phagosomes	P value 2
Bacteriab
Lp02	528	16/28	44	0.828	23/44	0.675
Beads coated with:
HtpB	678	16/32	48	NA	28/48	NA
GroEL	564	8/36	44	0.153	10/44	0.001
BSA	1,008	4/30	34	0.036	6/34	<0.001

^aOnly 3.4 to 8.3% of the cell sections observed showed phagosomes. The “+” phagosomes refer to those in contact with mitochondria; “−” phagosomes were not in contact with mitochondria. Association with vesicles or ER was not scored. “Total MT” refers to the total number of mitochondria observed in contact with phagosomes, and the “total number of phagosomes” refers to all of the phagosomes scored. P value 1 was calculated for differences in ratios of “+” phagosomes to total phagosomes in relation to HtpB-coated beads, using the Fisher exact test. P value 2 was calculated for differences in ratios of the total MT to the total phagosomes in relation to HtpB-coated beads, using the Fisher exact test. NA, not applicable.

^bWe did not find enough phagosomes containing Lp02dotB to provide a meaningful quantification. Only two phagosomes were observed, with no associated mitochondria.