Enhancement of Histamine Release from Rat Peritoneal Mast Cells Exposed to Formaldehyde

Abstract

While formaldehyde is an indoor and outdoor pollutant, little is known about the effect of formaldehyde exposure on induction of allergic and inflammatory reactions. To examine the effects of in vitro exposure to formaldehyde on rat mast cell functions, purified peritoneal mast cells (PMC) were exposed to 1, 5, 10, and 50 ppm formaldehyde for 30 min and then incubated with secretagogues. Histamine release from PMC stimulated with A23787 or anti-rat IgE was significantly enhanced at 5 ppm formaldehyde. Substance P-induced histamine release was affected at 10 and 50 ppm formaldehyde; however, no enhancement of substance P-induced histamine release was seen below 5 ppm. The effects of modulators of mediator release on enhanced histamine release from formaldehyde-exposed PMC induced by immunological and nonim-munological stimulation were also examined. Pretreatment with cholera toxin or dexa-methasone did not prevent the formaldehyde-induced enhancement in histamine release. Howevec pretreatment with p-bromophenacyl bromide, an inhibitor of phos-pholipase A₂, prevented the stimulatory effects of formaldehyde on A23187 and anti-rat IgE-induced histamine release. These results suggest that formaldehyde gas can modify mast cell mediator release and may be partly relevant in the induction of many inflammatory and allergic diseases.