Cytokine mRNA expression in human epidermis after patch treatment with rhus and sodium lauryl sulfate

Cytokines have been shown to play a pivotal role in the development and elicitation of contact hypersensitivity reactions. The sources of these cytokines in the skin include T cells, keratinocytes, and Langerhans cells.

In an effort to characterize the cytokines involved in the elicitation phase of a contact allergic response, we examined mRNA expression in human epidermis following patch testing with a known allergen and vehicle.

Allergic subjects were patch tested with poison ivy allergen (rhus), irritant (sodium lauryl sulfate [SLS]) and vehicle controls for 24 hours. Epidermal samples were obtained from the patch sites by a suction blister technique. Total RNA was isolated from the epidermis and the level of cytokine gene expression was determined using reverse transcriptase polymerase chain reaction (RT-PCR). PCR products for the various cytokines were confirmed and semiquantitated by liquid hybridization with (32)P-labeled product-specific probes.

Results of liquid hybridization confirmed the presence of message for interleukin (IL)-2, IL-4 and IL-10 in rhus, SLS, and vehicle treated sites. Generally, in rhus treated sites, the steady state level of message for IL-2 was highest, followed by IL-4 and IL-10, in decreasing levels. In contrast, only minimal expression of mRNA for these cytokines was observed in irritant and vehicle treated sites. Interestingly, interferon (IFN)-gamma mRNA was not detected at 24 hours in rhus, SLS, or vehicle treated sites.

These preliminary results indicate differences in the steady state levels of cytokine mRNA in allergen versus vehicle and irritant treated sites at 24 hours after treatment.