IMMUNOASSAY OF HEMOGLOBIN-ACRYLONITRILE ADDUCT IN RAT AS A BIOMARKER OF EXPOSURE

Acrylonitrile (AN) is a rat carcinogen. Human exposure may come from c hemical industries and smoking. A haemoglobin adduct of acrylonitrile (Hb-AN) has been used as a biomarker of exposure by means of gas chrom atography-mass spectrometry (GC-MS) analysis. We have developed specif ic monoclonal antibodies (Mab) to human Hb-AN and wish to report evalu ation of an immunoassay in rats using an Mab that cross-reacts with ra t Hb-AN. A dose response study of LD 0, 10, 50, and 90 in Sprague-Dawl ey rats was undertaken, with each rat receiving [2,3-C-14]AN at 50 mu Ci kg(-1) sc, and Hb from an aliquot of blood was taken for covalent b inding analysis by liquid scintillation spectrometry and fluorescence ELISA. The dose responses of rats at 0.25, 0.5, 10, and 2.0 h after AN doses of 20, 50, 80, 115 mg kg(-1) were compared by both methods with Hb and globin samples. Regression analysis showed a linear relationsh ip between immunoassay and C-14-AN binding. This indicates that an ant igenic form of Hb-AN may be used as a surrogate of Hb-AN adduct. The s ensitivity of ELISA was tested in rats exposed for 1 h to sub-toxic do ses of AN(10-1.1 mg kg(-1)). Quantification of Hb-AN by immunoassay wa s achieved by calibration with a synthetic adduct HbAN4h, a reference adduct prepared by treating rat Hb with excess AN for 4 h. ELISA and G C-MS analysis of N-terminal valine-AN in the Hb-AN adduct were compare d and similar detection levels were found. This rat study appears to h ave validated the new immunoassay method for biomonitoring of AN expos ure.