Ginsberg G L, Atherholt T B, Butler G H
Department of Microbiology, Coriell Institute for Medical Research, Camden, New Jersey 08103.
J Toxicol Environ Health. 1989;28(2):205-20. doi: 10.1080/15287398909531341.
Benzo[a]pyrene (BaP)/DNA adduct formation appears to be involved in carcinogenesis, but the relationship between adduct formation and BaP-induced immunotoxicity is unknown. We compared DNA adduct formation (32P-postlabeling analysis) to suppression of polyclonal immune responses (3H-TdR incorporation and IgM secretion) and decreases in cell viability in B6C3F1 female mouse splenic leukocytes (SPL). BaP administration (200 mg/kg, ip) resulted in suppression of polyclonal responses and substantial DNA adduct formation in mouse SPL. SPL adduct levels were similar to those in liver, lung, kidney, and stomach. In vitro exposure of SPL to BaP without rat liver activation enzymes (S9) caused decreases in SPL viability and immune responses that were dependent on dose and exposure period. However, DNA adduct formation in SPL was very low between 1 and 200 microM BaP. S9 enhanced the toxicity of BaP for SPL cultures. Adduct formation was rapid and dose related in +S9 incubates. The low level of BaP activation by SPL was confirmed in microsomal incubations in which splenic microsomes exhibited much lower aryl hydrocarbon hydroxylase (AAH) activity and ability to form DNA-adducting metabolites than did microsomes from liver or lung. Results indicate that immunosuppression produced by BaP in these systems was due to cytotoxic effects. It appears that these effects were caused by two separate mechanisms, one dependent on and one independent of DNA adduct formation. Since SPL had high levels of DNA adducts after ip injection of BaP, reactive metabolites of BaP may be involved in the immunotoxicity seen in vivo.
苯并[a]芘（BaP）/DNA加合物的形成似乎与致癌作用有关，但加合物形成与BaP诱导的免疫毒性之间的关系尚不清楚。我们将DNA加合物的形成（32P后标记分析）与多克隆免疫反应的抑制（3H-TdR掺入和IgM分泌）以及B6C3F1雌性小鼠脾白细胞（SPL）细胞活力的降低进行了比较。给予BaP（200mg/kg，腹腔注射）导致小鼠SPL中多克隆反应受到抑制，并形成大量DNA加合物。SPL中的加合物水平与肝脏、肺、肾脏和胃中的相似。在无大鼠肝脏活化酶（S9）的情况下，将SPL体外暴露于BaP会导致SPL活力和免疫反应降低，这取决于剂量和暴露时间。然而，在1至200μM BaP之间，SPL中的DNA加合物形成非常低。S9增强了BaP对SPL培养物的毒性。在有S9的孵育中，加合物的形成迅速且与剂量相关。在微粒体孵育中证实了SPL对BaP的活化水平较低，其中脾微粒体表现出比肝脏或肺微粒体低得多的芳烃羟化酶（AAH）活性和形成DNA加合代谢物的能力。结果表明，BaP在这些系统中产生的免疫抑制是由于细胞毒性作用。这些作用似乎是由两种独立的机制引起的，一种依赖于DNA加合物的形成，另一种与之无关。由于腹腔注射BaP后SPL中有高水平的DNA加合物，BaP的活性代谢物可能参与了体内所见的免疫毒性。
