Objective Dioxin, a known risk factor for lymphoma, and numerous other xenobiotics, induce their own metabolism by initially activating the aryl hydrocarbon receptor (AhR). We used the serum samples of participants to the multicentre Italian study on gene-environment interactions in lymphoma aetiology (ITGxE) to explore AhR activation as an intermediate step in dioxin-induced risk of lymphoma, and particularly B-cell lymphoma subtypes.

Methods Overall, serum samples of 343 lymphoma cases and 1899 population and hospital controls from five Italian areas (Florence, Bari, Perugia, Novara, and central and southern Sardinia) were available for study. A 50 microliter serum aliquot of each study participant potentially carrying the AhR activator, was added to HepG2 cells, transfected with specific reporter systems including the DRE specific AhR activating sequence upstream to the luciferase reported gene. The intensity of light generated by the Dual-Luciferase Assay, captured with a luminometer, is directly correlated with the concentration and potency of the inducing xenobiotic. Risk of lymphoma overall and by its major B-cell specific subtypes associated with AhR activation positivity as a binary outcome was calculated using an unconditional logistic regression model adjusted by age and gender.

Results Among the B-cell lymphoma subtypes, there was a significant two-fold excess risk for follicular lymphoma (OR = 2.0, 95% CI: 1.0, 4.0) and chronic lymphocytic leukaemia (OR = 2.3, 95% CI: 1.0, 5.0). No increase in risk associated with AhR positivity was observed for the other B-cell lymphoma subtypes we tested, namely diffuse large B-cell lymphoma, and multiple myeloma, nor for Hodgkin lymphoma.

Conclusions Our results show that the Dual-Luciferase Assay is a reliable and inexpensive test to detect AhR activation and its role in lymphomagenesis.