Fecal bacteria isolated as described elsewhere (131) from stool samples from RBP (N= 9, SBP 115 mmHg) and HTN (N=13, SBP 145 mmHg) subjects were stained with PE-conjugated Anti-Human IgA to measure the percentage of IgA-coated bacteria in stool by flow cytometry. A, Unstained control. B and C, Representative IgA-staining of fecal bacteria from a normotensive (B) and a hypertensive subject (C). D, Cumulative data, percentage of IgA-coated and non-coated bacteria in stool of 9 normotensive and 13 hypertensive subjects determined by flow cytometry (mean ± standard error of the mean).