Monoclonal antibody labeling for cytokeratins and filaggrin in the human pilosebaceous unit of normal, seborrhoeic and acne skin.

The distribution of cytokeratins and filaggrin in human pilosebaceous unit was investigated in specimens obtained from normal (n = 15), seborrhoeic (n = 6), and acne skin (n = 6), using the monoclonal antibodies CK8.12, CK8.13, CK4.62, CK8.60, KL1, PKK2, RPN 1160, and an antibody for filaggrin. The type and amount of cytokeratin content was correlated with the stage of cell differentiation in these three skin types. In all specimens studied the sebocytes. The sebaceous duct cells, and the infundibular cells contained cytokeratins, no clear differences were found between normal, seborrhoeic, and acne skin. During sebocytic maturation the amount and type of cytokeratin content changed gradually and the labeling pattern was partly different compared to the interfollicular epidermal pattern. In the sebaceous duct and the infundibulum, the labeling pattern using KL1, CK8.12, and CK8.13 was similar to that seen in interfollicular epidermis, whereas labeling with CK8.60 and PKK2 was different. These findings indicate that sebaceous duct and infundibular cells express transitional patterns of differentiation between epidermal keratinocytes and sebocytes. Filaggrin was expressed only in some sebaceous duct cells and in infundibular cells. In seborrhoeic and in acne skin, however, the reactivity of antibody to filaggrin was more intense and was already observed in the lower parts of the sebaceous duct and the infundibulum. Although no filaggrin was found in the intermediate cells of the sebaceous duct and the infundibulum in normal skin, these cell types clearly contained filaggrin in seborrhoeic and acne skin.