3H-thymidine labelling of epidermis and dermal infiltrate in psoriatic erythroderma.

The comparative pattern of 3H-thymidine (3H-T) pulse labelling in lesions of psoriatic erythroderma (3 cases) and of psoriasis vulgaris (20 cases) has been studied by means of radioautography. In the epidermis, no difference was noted between the two types of lesions concerning the epidermal 3H-T labelling index (L.I.) and the localization of labelled cells. The 3H-T L.I. of "round" cells infiltrating the dermis was much higher in lesions of psoriatic erythroderma (4.03 +/- 0.56%) than in lesions of psoriasis vulgaris (0.62 +/- 0.21%), and the difference is highly significant (p less than 0.0001). The findings indicate that most of these labelled cells could well be lymphoblasts, suggesting that an immunological process is possibly involved in the pathogenesis of psoriatic erythroderma.