TABLE 2.

Effects of low-dose gentamicin on intracellular and extracellular bacterial growth in macrophages incubated with or without IFN-γ^a

Concn of gentamicin (μg/ml)	No. of CFU/wellb
	Without IFN-γ	With IFN-γ
	Supernatants
0	>540,000	>540,000
1	15,048 ± 2,784	14,040 ± 1,887
2	1,125 ± 498	716 ± 195
4	150 ± 42	533 ± 90
	Total (supernatants + adherent macrophages)
0	>540,000	>540,000
1	343,500 ± 26,900	184,900 ± 10,400
2	387,700 ± 19,700	142,500 ± 3,200
4	306,100 ± 14,600	179,900 ± 6,900

^aPeritoneal macrophages were infected with 16M without opsonins and extracellular bacteria were washed off. Monolayers were replenished with DME-FBS-MCSF containing indicated concentrations of gentamicin with or without IFN-γ. After 48 h of incubation, B. melitensis CFU in culture supernatants (extracellular 16M) were determined by serial dilution and plating of supernatants on Brucella agar. The number of intracellular bacterial CFU was determined by lysis of monolayers followed by serial dilution and agar plating. 

^bValues are the mean ± SEM CFU/well from five replicate wells from one of two similar experiments.