Differentiation of prohaptens from direct acting contact chemical allergens using a cytochrome p450 reductase deficient mouse model.
Chipinda-I; Blachere-FM; Anderson-SE; Siegel-PD
Toxicologist 2011 Mar; 120(Suppl 2):17-18
The murine local lymph node assay (LLNA) is a well accepted, validated 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. The objective of this study was to assess the utility of a pan microsomal metabolic deficient mouse (CPR low/low) to distinguish between direct acting haptens and prohaptens in the LLNA. LLNA cell proliferation was compared in C57BL/6J (B6) wild type vs. homozygous CPR low/low mouse, congenic with the B6 strain, having a hypomorphic NADPH-cytochrome P450 reductase (CPR) gene resulting in low microsomal enzyme activity. The known prohaptens, benzo(a)pyrene (BaP), carvone oxime (CVO) and paracetamol (PCM) and direct binding haptens, oxazolone (OX), 4-ethoxymethylene-2-phenyl-2-oxazolin-5-one (EtOX), and N-acetylbenzoquinoneimine (NABQI) employed in the present study. Skin microsomes from the wild type (WT) and CPR low/low homozygous (HM) and heterozygous (HT) knock-out (KO) mice were assayed and compared for CPR activity. Lymphocyte proliferative responses to BaP, CVO and PCM were significantly abrogated by 36.4%, 45.2% and 50.8%, respectively; in CPR low/low 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 KO mice compared to the WT. Results of the present study suggest potential utility employing the LLNA in the CRP low/low mouse in conjunction with WT to differentiate pro- vs. direct acting haptens.
Biological-effects; Cell-biology; Cell-division; Cellular-reactions; Chemical-hypersensitivity; Chemical-reactions; Cytotoxic-effects; Exposure-levels; Laboratory-animals; Laboratory-testing; Microscopic-analysis; Nanotechnology; Physiological-effects; Quantitative-analysis; Skin-exposure; Skin-irritants; Statistical-analysis; Toxic-effects
The Toxicologist. Society of Toxicology 50th Annual Meeting and ToxExpo, March 6-10, 2011, Washington, DC