Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown,WV 26505-2888, USA.
Toxicol Appl Pharmacol. 2011 May 1;252(3):268-72. doi: 10.1016/j.taap.2011.02.018. Epub 2011 Mar 3.
The murine local lymph node assay (LLNA) is a validated, well accepted method for identification of chemical contact allergens. Both direct acting haptens and prohaptens (requiring metabolic activation) can be identified, but not differentiated by this assay. This study was used to assess the utility of a pan microsomal metabolic deficient mouse to distinguish between direct acting haptens and prohaptens in the LLNA. Hapten and prohapten induced cell proliferation was compared in C57BL/6J (B6) wild type (WT) versus homozygous (HO) knockout mice with a hypomorphic NADPH-Cytochrome P450 Reductase (CPR) gene (termed Cpr(low/low)) resulting in low CPR enzyme activity. Mice were dosed with known prohaptens; benzo(a)pyrene (BaP), carvone oxime (COx) and paracetamol (PCM) and haptens; oxazolone (OX), 4-ethoxymethylene-2-phenyl-2-oxazolin-5-one (EtOX), and N-acetylbenzoquinoneimine (NABQI) in this study. Skin microsomes from the WT, HO and heterozygous (HT) Cpr(low/low) mice were compared and evaluated for CPR activity. Lymphocyte proliferative responses to BaP, COx and PCM were significantly abrogated by 36.4%, 45.2% and 50.8%, respectively; in Cpr(low/low) knock out (KO) mice versus WT mice; while the lymphocyte proliferative responses to the direct acting haptens OX, EtOX and NABQI were comparable. CPR activity, determined as Units/mg protein, was determined to be significantly lower in the Cpr(low/low) mice compared to the WT. Results of the present study suggest potential utility of the Cpr(low/low) mice in the LLNA to differentiate prohaptens from direct acting haptens.
小鼠局部淋巴结检测（LLNA）是一种经过验证、被广泛接受的用于识别化学接触过敏原的方法。直接作用的半抗原和原半抗原（需要代谢激活）都可以被识别，但不能通过该检测方法进行区分。本研究旨在评估泛微粒体代谢缺陷小鼠在 LLNA 中区分直接作用半抗原和原半抗原的能力。在 C57BL/6J（B6）野生型（WT）和纯合子（HO）NADPH-细胞色素 P450 还原酶（CPR）基因缺失（称为 Cpr(low/low)）的同源敲除（KO）小鼠中比较了半抗原和原半抗原诱导的细胞增殖，导致 CPR 酶活性降低。在这项研究中，用已知的原半抗原苯并[a]芘（BaP）、香芹酮肟（COx）和对乙酰氨基酚（PCM）和半抗原恶唑酮（OX）、4-乙氧基亚甲基-2-苯基-2-恶唑啉-5-酮（EtOX）和 N-乙酰苯醌亚胺（NABQI）对小鼠进行了给药。比较了 WT、HO 和杂合子（HT）Cpr(low/low) 小鼠的皮肤微粒体，并评估了它们的 CPR 活性。与 WT 小鼠相比，BaP、COx 和 PCM 对 Cpr(low/low) KO 小鼠的淋巴细胞增殖反应分别显著降低了 36.4%、45.2%和 50.8%；而 OX、EtOX 和 NABQI 等直接作用半抗原的淋巴细胞增殖反应则相当。CPR 活性，以单位/毫克蛋白表示，在 Cpr(low/low) 小鼠中明显低于 WT 小鼠。本研究的结果表明，Cpr(low/low) 小鼠在 LLNA 中可能具有区分原半抗原和直接作用半抗原的潜力。
