Expression of T-cell cytokines in challenged skin of murine allergic contact photosensitivity: low responsiveness is associated with induction of Th2 cytokines.

Murine contact photosensitivity (CPS) to 3,3',4', 5-tetrachlorosalicylanilide (TCSA) is genetically controlled mainly by the major histocompatibility complex. The H-2(b,d) haplotypes are closely associated with high responders, whereas mice with H-2(k) are low or non-responders. We found that BALB/c (H-2(d)) mice were high responders in CPS not only to TCSA but also to chlorpromazine (CPZ) and benzocaine, whereas AKR/n (H-2(k)) mice were hyporesponsive to these three photoallergic agents. To elucidate the relationship between CPS responsiveness and T helper cell induction, the expression of T-cell cytokines was examined by reverse transcriptase polymerase chain reaction in the elicited skin of CPS to the three chemicals. The expression levels of interleukin(IL)-2 and interferon-gamma mRNAs were markedly higer in BALB/c mice than AKR/n mice, whereas mRNA for IL-4 was expressed strongly in AKR/n mice. These data suggest that the hyporesponsiveness of CPS to the photoallergens in AKR/n mice is closely associated with the activation/induction of Th2 cytokines at the challenged sites.