STABLE EXPRESSION OF CD1A MOLECULE IN HUMAN EPITHELIAL-CELL LINES SHOWS TEMPERATURE-DEPENDENT EXPRESSION AND AFFECTS CELL MORPHOLOGY AND GROWTH

The human CD1a molecule is a transmembrane protein which shares struct ural similarities with HLA class I molecules, It has restricted tissue distribution in normal individuals, and is a useful diagnostic marker for certain disease states such as Langerhans cell histiocytosis. In order to investigate the function of this molecule, a cDNA fragment en coding the CD1a molecule was cloned into several EUKARYOTIC expression vectors which were then used to establish human epithelial cell lines stably expressing the membrane-bound CD1a molecule, Human keratinocyt es (HaCaT) and epithelial cells (HeLa) stably expressing C-D1a were es tablished by retroviral-mediated gene transfer and DNA transfection, r espectively, Expression and localization of the CD1A molecule were the n confirmed by Northern blot analysis and immunofluorescence methods. CD1a expression appears to have profound effects on cellular growth an d morphology. Both stably CD1a-expressing HeLa and HaCaT cells showed increased doubling times, and up to 20% of CD1a-expressing cells showe d altered cell morphology. Clonogenicity experiments demonstrated a re duction in colony size and plating efficiency was augmented in CD1a-po sitive cells when compared with vector-transfected/infected controls, Our findings suggest that CD1A expression may act as a negative growth regulator in these cells in vitro. Furthermore, lower temperatures gr eatly enhanced the expression of CD1a at both the protein and mRNA lev els in a time-dependent fashion, Since the physiological skin temperat ures lie well below the core temperature, this observation may have im portant implications in the study of Langerhans cells in vitro.