Figure 1. Induction of skin inflammation by Aldara cream in mice lacking B cells.

Aldara or emollient cream was applied to the shaved back of mice on 7 consecutive days. Mb1-cre homozygous (mb1-cre ho) mice possess a minimal number of B cells. Each experiment was done three times with four mice in each group. (a) Mice treated with Aldara developed psoriasis-like skin inflammation with erythema, scaling and thickening. (b) mPASI reflecting the intensity of skin inflammation. Two-tailed unpaired Student's t-test was performed for statistical analysis. Data are shown as means±s.e.m. (c) Light microscopy examination of skin sections stained with H&E, or with Abs against the keratins K6, K10 and K14, and S100A8, respectively. Sections of skin treated with Aldara show, in contrast to skin exposed to emollient cream, parakeratosis (retention of nuclei in the ‘stratum corneum'), acanthosis (thickening of the ‘stratum spinosum') and elongation of the dermal papillae. Scale bars, 50 μM. H&E, haematoxylin and eosin.