Cytokine profiling for chemical sensitizers: application of the ribonuclease protection assay and effect of dose.

Exposure to chemicals in domestic and occupational settings may contribute to increases in asthma and allergy. Airway hypersensitivity (AHS) is T helper-2 (Th2) cell associated, whereas contact hypersensitivity (CHS) is T helper-1 (Th1) cell associated. The distinct cytokine profiles produced by these cells may provide a means of distinguishing respiratory sensitizers from contact sensitizers. In this study, female BALB/c mice were exposed twice on the flanks and three times on the ears using the airway sensitizer trimellitic anhydride (TMA) or the contact sensitizer dinitrochlorobenzene (DNCB). At various times following exposure, total mRNA was extracted from draining lymph node cells and cytokine mRNA profiles analyzed using a multiprobe ribonuclease protection assay (RPA). The Th2 cytokines IL4, IL10, and IL13 were significantly increased in response to TMA compared to DNCB, with optimal detection occurring 14 days following initial exposure. To determine its effect, dose was varied in flank exposures, ear exposures, or both simultaneously. When dose was varied during flank exposures only, TMA induced higher levels of Th2 cytokines than DNCB at all doses tested. DNCB did not induce Th1 cytokines at any dose tested. Variation of TMA dose during both exposures similarly induced Th2 cytokines. Dose only appeared to be a factor when TMA concentration was varied during the ear exposures alone. Thus, these studies suggest that quantitative differences in Th2 responses between TMA and DNCB may be demonstrated over a wide range of doses and these differences may be detected by RPA following dermal exposure to these sensitizers.