Pituitary adenylate cyclase-activating polypeptide inhibits cutaneous immune function.

Epidermal nerves are closely associated with Langerhans cells (LC) and may be able to release factors, such as calcitonin gene-related peptide and epinephrine, that affect LC function. LC and the LC-like cell line XS106 express mRNA for the pituitary adenylate cyclase-activating polypeptide (PACAP) receptors VPAC1 and VPAC2. We examined whether PACAP regulates cutaneous immunity. Intradermal administration of PACAP prior to application of a contact sensitizer at the injected site inhibited the induction of contact hypersensitivity. Pretreatment of murine epidermal cells enriched for LC content (approximately 12% LC) with PACAP inhibited their ability to elicit delayed-type hypersensitivity in previously immunized mice. In vitro, PACAP suppressed the ability of both murine epidermal cells and highly purified LC (approximately 95%) to present antigen to a T cell clone and hybridoma. Furthermore, in LC and the XS106 cell line, PACAP inhibited the LPS/GM-CSF-induced stimulation of IL-1beta secretion and augmented IL-10 production. PACAP also down-regulated CD86 expression in LPS/GM-CSF-stimulated XS106 cells. The immunosuppressive effects of PACAP may be due to modulation of cytokine production and CD86 expression.

Minocycline-induced hyperpigmentation of the tongue: successful treatment with the Q-switched ruby laser.

BACKGROUND: Minocycline-induced hyperpigmentation (MIH) is a benign condition that may persist for years despite abrogation of therapy. The Q-switched ruby laser (QSRL) has been successful in removing such lesions from the skin. To date there is no documentation of QSRL or any laser being used to treat lingual hyperpigmentation associated with minocycline therapy. OBJECTIVE: Long-term follow-up results are reported for the use of QSRL to treat lingual hyperpigmentation. The literature is reviewed comparing the use of different laser systems on MIH. METHODS: A 26-year-old woman with pigment changes of the tongue and buccal mucosa due to long-term minocycline therapy was treated with four consecutive sessions with QSRL (694 nm, 20-nsec pulse duration, and 6.5 mm spot size) at 3.6-4.0 J/cm2. RESULTS: A 90% resolution was achieved after three treatments. After the final treatment the lesions were completely gone. There were no side effects reported. No new pigment was detected at follow-up. CONCLUSION: Treatment with the QSRL is a safe and effective strategy for treating hyperpigmentation of the tongue associated with minocycline therapy.