Oxidative metabolism of neutrophils in vitro and human mercury intolerance

Neutrophils from 22 patients and 15 healthy controls were exposed in vitro to mercuric chloride and phenyl mercuric acetate in increasing doses and the superoxide anion production of the isolated cells was measured using the NBT (nitroblue tetrazolium) test. The patients were chosen for the study on the basis of their history following exposure to amalgam dust during dental treatment. Based on their psychosomatic response to challenge with percutaneously administered low doses (i.e. patch test doses) of metallic mercury and phenyl mercuric acetate, they were subdivided into two groups: 12 patients with a high score on the psychometric test (positive or mercury-intolerant patients) and 10 with a negative or low score (negative or mercury-tolerant patients). A significant difference in the NBT reduction of unstimulated neutrophils and one concentration of mercuric chloride was found between the tolerant and intolerant patients. Neutrophils from tolerant patients showed a peak NBT value at lower concentrations of mercuric chloride than did cells from the healthy controls and the intolerant patients. When the cells were exposed to increasing amounts of phenyl mercuric acetate, the positive and negative patients differed significantly. Furthermore, an inhibition was noted of the NBT response. Thus, the in vitro oxidative response pattern of neutrophils differs in subjects who do or do not react psychosomatically when exposed to in vivo provocations with low doses of mercury. The findings may be relevant for those complaining of subjective symptoms related to mercury released from dental amalgam and could provide some understanding of the pathogenetic mechanisms.