Local lymph node assay responses to paraphenylenediamine: intra- and inter-laboratory evaluations

The hair dyes PPD and PTD fail to induce a TH2 immune response following repeated topical application in BALB/c mice

“…Among hair dye molecules, the most commonly suspected allergenic species are oxidation products of aromatic amines, such as PPD and PTD (Aeby et al, 2009;Basketter et al, 2010). These are readily identified in predictive assays as having the potential to give rise to cell-mediated (T H 1) allergy (Warbrick et al, 1997;Aeby et al, 2004Aeby et al, , 2009Gerberick et al, 2005;Kern et al, 2010). However, there have been very occasional reports of an immediate-type hypersensitivity typically mediated by IgE antibodies (summarized in Table 1).…”

“…Woolhiser et al, 2000). The concentrations of TDI, PPD, and PTD chosen were based on information obtained from other studies: (1) a T H 2 response to 2,4,6-trinitro-1-chlorobenzene was induced following repeated dermal exposure to concentrations of chemical in excess of the induction threshold for contact sensitization in the LLNA (Nagai et al, 1997); (2) the EC 3 values for PPD and PTD in the LLNA are reported to be ~0.1%, so using the 0.6% dose is in excess of the EC 3 (Warbrick et al, 1997(Warbrick et al, , 2000Aeby et al, 2004); and, (3) TDI and other isocyanates have been show to induce positive LLNA responses at doses between 0.1 and 0.3% (Dearman et al, 1992(Dearman et al, , 1996. Accordingly, we elected to use 0.6% for each of these allergens, considering these concentrations sufficient for induction of an immune response.…”

“…The concentrations of chemicals were chosen to optimize our ability to detect a T H 1 and/or T H 2 response. This study exaggerated the reported induction threshold for contact allergy in the mouse by a factor of 6 for PPD (EC 3 equal to or very near to 0.1% [Warbrick et al, 1997]) and a factor of 3 for PTD (Aeby et al, 2004). The concentration of TDI was chosen based on doses used in other dermal exposure mouse models and shown to induce T H 2 responses (van Och et al, 2000).…”

Evaluation of Allergenicity of Constituents of Myoga Using the Murine Local Lymph Node Assay

“…The effective concentration of a stimulation index of 3 (EC3) for each experimental group was calculated by linear interpolation (IS, [20][21][22][23][24]. In each case, a stimulation index (SI) relative to the concurrent vehicletreated control was derived.…”

“…Little variation was observed in the levels of 3HTdR incorporation in LNC derived from AOO vehicle-treated animals with levels extending over a relatively narrow range from 37dpmlnode to 146dpmlnode in the case of a-pinene to limonene, respectively. These data demonstrated a high degree of inter-experimental consistency between the LLNA conducted during these investigations and those reported previously (24). For limonene at a test concentration of 100%, the level of 3HTdR incorporation was 1035dpml node and the corresponding SI was 7.09.…”