Cytokines modulate terminal differentiation and the expression of predesquamin in cultured keratinocytes

Predesquamin is a glycoprotein that we have isolated from human epidermis. Its monospecific polyclonal antibody immunolocalizes to the lower stratum corneum. We have previously found that it is not expressed in primary keratinocyte cultures unless both interferon-gamma and serum are added to the culture media. We now show similar results with interleukin-1 alpha substituted for interferon-gamma (but not with retinoic acid). Predesquamin is expressed in media supplemented with both cytokines (with or without serum), accompanied by the observation of larger outer squames and a more mature pattern of desquamation. As both cytokines are naturally present in the epidermis, this suggests that they contribute to desquamation in vivo. The predesquamin expression is demonstrated by Western blots of cell extracts with the specific antibody. Corresponding morphological changes are illustrated by phase-contrast microscopy.