Levels of endogenous <i>Burkholderia</i>-reactive antibodies present in normal human serum.

<p><i>B. pseudomallei,</i> B. <i>thailandensis</i>, and <i>E. coli</i> were incubated with the indicated serum concentrations, washed, and stained with both an APC-labeled anti-human IgM antibody and R-PE-labeled anti-human IgG antibody. Samples were analyzed by flow cytometry and the data reported as mean fluorescence intensity (MFI). The bars represent the mean±SEM of two separate experiments performed with duplicate samples. The single asterisk (*) indicates a statistically significant increase (<i>P</i>≤0.05) over unopsonized bacteria. The double asterisks (**) indicate a statistically significant difference (<i>P</i>≤0.05) over 20% NHS-opsonized <i>B. pseudomallei</i> and <i>B. thailandensis</i> values.