AROMATIC DNA ADDUCT LEVELS IN HUMAN PERIPHERAL-BLOOD LYMPHOCYTES AND TOTAL WHITE BLOOD-CELLS BY P-32 POSTLABELING - NEED FOR VALIDATION

Long-lived lymphocytes tend to have higher P-32-postlabelling-measured levels of adducts than short-lived granulocytes in environmental and life-style associated (i.e. smoking) exposures. With the aim of invest igating this issue for occupational exposure to PAH and contributing t o further validation of some technical aspects of the P-32-postlabelli ng assay, two Italian laboratories analysed PAH-DNA adducts from lymph ocytes and total white blood cells (WBC). Seventy-seven blood samples from coke-oven workers employed at a steel plant located in Taranto, S outhern Italy, and 14 samples from control subjects were collected. At the University of Padua, DNA was purified from peripheral blood lymph ocytes (PBL). Two years later, at the University of Bari, white blood cells (WBC) were isolated from replicate blood samples stored at -80 d egrees C and DNA purified by the same method. In both cases, the nucle ase P1-modified postlabelling assay was used to determine aromatic DNA adduct levels. The mean adduct levels were 5.13 +/- 3.37 (Padua) and 2.48 +/- 1.27 (Bari) per 108 nucleotides. Both laboratories observed l arge interindividual variations of adduct levels ranging from 0.09 to 18.93 per 10(8) nucleotides. Both the correlation and the agreement of the two sets of data were assessed. Slight correlation (r = 0.39; p < 0.01) and a poor level of agreement were found, the intra-class corre lation coefficient being equal to 0.05. Better correlation coefficient (r' = 0.54, p < 0.01) and intra-class correlation coefficient (r = 0. 50) were observed comparing only the adduct levels determined on the d iagonal zone (DRZ). Our findings seem to confirm the same divergence r eported in the literature on DNA adduct levels between lymphocytes and granulocytes.