Heterogeneity of hypochlorous acid production in individual neutrophil phagosomes revealed by a rhodamine-based probe

The rhodamine-based probe R19-S has been shown to react with hypochlorous acid (HOCl) to yield fluorescent R19, but not with some other oxidants including hydrogen peroxide. Here, we further examined the specificity of R19-S and used it for real-time monitoring of HOCl production in neutrophil phagosomes. We show that it also reacts rapidly with hypobromous acid, bromamines, and hypoiodous acid, indicating that R19-S responds to these reactive...