Figure 5. Addition of iron chelator negates the effect of Hb concentration on in vitro mycobacterial growth.

(a) BCG Pasteur growth was measured following 96 hour co-culture with human PBMC with the addition of increasing concentrations of Hb, with (dotted line) or without (solid line) treatment with 8 μM DFO. Points represent the mean of 6 individuals and bars the SEM. There was a clear reduction in mycobacterial growth at all concentrations following treatment with DFO. There was a significant increase in mycobacterial growth between 0.1 mg/ml and 1 mg/ml Hb in the absence of DFO (p < 0.05, paired t-test), but addition of DFO removed this effect. (b) BCG Pasteur growth was measured following 96 hour co-culture with whole blood from 6 human volunteers with the addition of increasing concentrations of DFO. Lines represent individuals; points represent the mean of duplicates. Δ log₁₀ CFU = (log₁₀ CFU of sample - log₁₀ CFU of control).