Hypotheses for a re-evaluation of peroxidase activity in the oral inflammation: NAD(P)H-dependent hypohalite reduction in human neutrophils.

The balance of NADH oxidation by neutrophil lysates in the presence and in the absence of peroxidase/H2O/halide systems, pointed out a NADH oxidation excess when these hypohalite generators were actually present. This unexplained NADH consumption could not be attributed to a direct oxidation by hypohalites nor by the lysate self. Using OCI- as substrate, the NADH oxidation excess ranged from 52 to 99 mU/ml at pH 7.40 and from 446 to 1346 mU/ml at pH 6.00 (N = 6). Similar results were also found while using hypoiodous and hypothiocyanous compounds at pH 7.40 but not at pH 5.50. The authors discuss different hypotheses to explain this phenomenon and accordingly elaborate on the possible consequences of neutrophils degranulation in the oral tissues during inflammation processes.