EOSINOPHIL CATIONIC PROTEIN (ECP), HISTAMINE AND TRYPTASE IN PERIPHERAL-BLOOD BEFORE AND DURING INHALATION CHALLENGE WITH TOLUENE DIISOCYANATE (TDI) IN SENSITIZED SUBJECTS

To determine whether the measurement of specific markers of inflammato ry cells in peripheral blood might be used to detect the inflammatory activity in the airways in asthma induced by toluene diisocyanate (TDI ), we measured the levels of eosinophil cationic protein (ECP), histam ine and tryptase in peripheral blood before and during inhalation chal lenge with TDI or methacholine in two groups of subjects who exhibited or did not exhibit an asthmatic reaction after exposure to toluene di isocyanate in the laboratory. When the subjects developed a late asthm atic reaction after exposure to TDI, they showed an increase in their ECP serum levels. By contrast, there were no significant changes in se rum ECP levels after exposure to TDI in the control group or after met hacholine challenge in either group. Tryptase levels in serum were not detectable before or during inhalation challenge with TDI or methacho line. There was no significant increase in plasma histamine levels dur ing inhalation challenge with TDI or methacholine. These results sugge st that eosinophils are 'activated' in subjects who develop a late ast hmatic reaction after exposure to TDI and that the measurement of ECP levels in peripheral blood may be a useful marker to monitor airway in flammation.