Simultaneous measurements of cytoplasmic Ca2+ responses and intracellular pH in neutrophils of localized aggressive periodontitis (LAP) patients

In view of the reports that polymorpho- nuclear leukocytes (PMN) of patients with localized aggressive periodontitis (LAP) exhibit hyper-re- sponsiveness to stimulation, it has been suggested that such abnormalities could lead to PMN-medi- ated tissue damage during inflammation. To deter- mine whether these abnormalities include signal transduction, we compared cytoplasmic calcium concentration ((Ca 2 )i) and cytoplasmic pH (pH i ) changes, early stimulus responses to chemo- tactic agents, of LAP versus control (C)-PMN and explored whether these could be modulated by sensitizing cytokines or calcium channel-blocking agents. PMN responses of LAP patients were compared with age- and gender-matched con- trols. (Ca 2 )i and pHi were measured fluori- metrically using 1H-indole-6-carboxylic acid, 2-(4-(bis(2-((acetyloxy)methoxy)-2-oxoethyl)- amino)-3-(2-(2-(bis(2-((acetyloxy)methoxy)-2- oxoethyl)amino)-5-methylphenoxy)ethoxy)phenyl)-1 and 2,7-bis-(carboxyethyl)-5(6)-carboxyfluores- cein as respective probes. Not only was the maxi- mal calcium response to chemoattractants higher in LAP-PMN, but also their subsequent intracellu- lar calcium redistribution was significantly slower. The slower calcium redistribution of LAP-PMN, but not their higher maximal calcium response, was successfully mimicked in C-PMN treated with Nifedipine™ or 1-(b-(3-(4-methoxyphenyl)propoxy)- 4-methoxyphenethyl)-1H-imidazole-HCl, both known to be inhibitors of membrane-associated calcium influx, but this redistribution was not af- fected when inhibitors of other calcium influx mechanisms, Diltiazem™ or Verapamil™, were used. Taken together, our findings indicate that certain early stimulus responses are aberrant in LAP-PMN, that internal redistribution of cytoplas- mic-free calcium is compromised, and, addition- ally, that a membrane-associated Ca 2 transport defect may be present. J. Leukoc. Biol. 78: 612-619; 2005.