FIG 5.

Ga-protoporphyrin inhibits intracellular M. abscessus growth. THP-1 cells were transformed and infected with M. abscessus ATCC 19977 for 1 h, washed, and cultured for up to 4 days in the presence of different concentrations of Ga-protoporphyrin as described in Materials and Methods. Ga-protoporphyrin significantly inhibited intracellular M. abscessus relative to the control (no Ga) or Ga(NO₃)₃ treated when expressed as the number of CFU/well (panel A) (P < 0.001) or when the data were expressed normalized to the control (no Ga). The time zero CFU count was 2.9 × 10⁴. No toxic effects of Ga-protoporphyrin against THP-1 cells were seen (panel C), as determined by MTT assay. *, P < 0.01; **, P < 0.001; n = 4 replicates.