Quantitative Analysis Of SjTRECs To Evaluate The Recent Thymic Output Function In Benzene-exposed Workers By Real-time PCR

Objective: To investigate the level of T-cell receptor excision DNA circles (TRECs) within peripheral blood mononuclear cells (PBMCs) in benzene-exposed workers and chronic benzene-poisoned patients, thereby to evaluate the content of naive T cells and the recent thymic output function. It would be expected to present advance data for study on the influence of benzene-exposed in host T cell immune function.Methods: The vector containing house-keeping gene RAG2 and TRECs was constructed by gene cloning and served as standard. Quantitative detection of TRECs in DNA of PBMCs from benzene-exposed workers (68 cases), dubitable chronic benzene-poisoned (21 cases), chronic mild benzene-poisoned (13 cases), chronic middling benzene-poisoned (5 cases) and chronic severely benzene- poisoned (10 cases) was preformed by real-time PCR using TaqMan technique. The TRECs levels were analyzed in different age, sex and duration of benzene-exposed groups. The TRECs levels in some benzene-poisoned cases were followed up in different time points up to 55 weeks. 34 normal individuals served as controls.Results: The Quantitative analysis of TRECs in PBMCs from benzene-exposed workers and benzene-poisoned patients by real-time PCR was established. In compare with TRECs level in normal individuals (7.39 6.83/1000 PBMCs), it was significant decrease of TRECs levels in all six groups with benzene-exposed workers (3.90 + 3.58/1000 PBMCs, P<0.01), dubitable benzene-poisoned (3.67 3.32/1000 PBMCs, P<0.01), chronic mild benzene-poisoned (3.04+4.65/1000 PBMCs, P<0.01), chronic middling benzene-poisoned (2.55 + 2.05/1000 PBMCs, P<0.01) and chronic severely benzene-poisoned (2.52 2.22/1000 PBMCs, P<0.01). The individual difference of TRECs levels (0.22-19.48/1000 PBMCs) was observed in benzene-exposed workers and patients with early stage of benzene-poisoned. In normal individuals and benzene-exposed groups,TRECs levels in older than 30 years group decrease significantly than younger group, but its level was no significantly difference in all benzene-poisoned groups. It could not been found any significantly different of TRECs levels in different sex groups or benzene-exposed duration groups. The TRECs level was persistent decrease in period of benzene poisoning, even if peripheral blood cell counts were became normal levels.Conclusions: It is the first report to describe the TRECs levels and thymic recent output function in benzene-exposed workers and patients with benzene-poisoned. The results indicated that TRECs levels were remarkable decrease in benzene-exposed workers and chronic benzene-poisoned patients. It may obviously damage the recent thymic output function and T cell immune function in benzene-exposed and benzene poisoning. The results indicated also that the sensitivity of damage of T cell immune function by benzene -exposed was different in different individuals.