Epidermal cyclic AMP is not decreased in psoriasis lesions.

The cyclic AMP level in epidermis of psoriatic patients was reappraised with a highly sensitive radioimmunoassay method in conjunction with an improved skin biopsy technique to avoid any artificial rise of cyclic AMP due to ischemia. Local intradermal injection before biopsy was avoided, since even saline injection caused a clear-cut ischemia effect. The results concur with our previous study: i.e., on a tissue dry weight or protein basis, the cyclic AMP level in the involved epidermis is 20% higher than that in the uninvolved spidermis of psoriatic patients, and on a DNA basis, there was no significant difference. The cyclic AMP level in normal epidermis from non-psoriatic subjects is the same as that in the uninvolved epidermis of psoriatic patients. Such characteristics in psoriatic lesions as the increased mitosis, incomplete, differentiation and increased glycogen content cannot be simply related to a cyclic AMP deficiency.