FIG. 6.

Quantitation of HNP binding to M. tuberculosis. (a) Fluorescence intensity of anti-HNP staining as a function of exposure to HNP-1. M. tuberculosis was exposed to increasing concentrations of HNP-1 and then stained with anti-HNP/Cy-5. Digital images were captured and deconvolved. The average intensity of Cy-5 fluorescence of individual organisms was calculated and plotted on the y axis versus the concentration of defensin on the x axis. Error bars, standard errors of 50 tubercle bacilli for each data point. (b) Exposure of M. tuberculosis to defensin during culture with human neutrophils. Average intensity and standard deviation of extracellular M. tuberculosis bacilli within 50 neutrophils infected with M. tuberculosis or 50 neutrophils infected with tuberculosis and treated with 100 U of TNF-α/ml were mapped to exposure via the equation for the standard curve shown in panel a.