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. 2012 Feb;91(2):275–284. doi: 10.1189/jlb.0711356

Figure 8. Stimulation of PMN histamine production by PAO1 P. aeruginosa in biofilms and prevention of activation by inhibition of phagocytosis.

Figure 8.

(A) Comparison of released and total histamine in PMNs purified from uninfected mouse BM (“Naïve PMN”) with histamine produced by naïve PMNs incubated separately with each of the following: live PAO1 strain P. aeruginosa (1:10 ratio; “PMN+PAO1”), PAO1 culture supernatants (“1× Supe” contains a dilution of supernatant equivalent to the amount conditioned by the number of bacteria used in the “PMN+PAO1” condition; “10× Supe” is a tenfold-higher concentration of supernatant), uninfected biofilm membrane (“PMN+Membrane”), infected biofilm membrane (“PMN+PAO1 Biofilm”), and PAO1 removed from biofilm and suspended in liquid (“PMN+PAO1 from Biofilm”). Values represent mean ± se; n = 3/experimental condition; *P < 0.05 and **P < 0.01. (B) Comparison of histamine in naïve PMN with histamine in naïve PMN incubated with PAO1 or with cytochalasin D (CytoD; 1 or 10 μg/ml), with or without PAO1. Values represent mean ± se; n = 3/experimental condition; *P < 0.05 (total histamine PMN+PAO1 vs. Naïve PMN or PMN+PAO1+CytoD 1 μg/ml); **P < 0.01 (total histamine PMN+PAO1 vs. PMN+PAO1+CytoD 10 μg/ml, released histamine PMN+PAO1 vs. naïve PMN or PMN+PAO1+CytoD 1 μg/ml); ***P < 0.001 (released histamine PMN+PAO1 vs. PMN+PAO1+CytoD 10 μg/ml).