1. ¹Inserm Unité 659, Faculté de médecine, Créteil, France
2. ²Sanofi Aventis, Rueil Malmaison, France
3. ³Sanofi Aventis, Labège, France
4. ⁴Department of Pathology, Inserm U 617, CHU Henri Mondor, AP-HP, Créteil, France
5. ⁵Department of Virology, Medical Research Institute, Tokyo, Japan

Correspondence: Dr C Schmitt, Inserm U659, Faculté de Médecine, 8 rue du Général Sarrail, 94010, Créteil Cedex, France. E-mail: christian.schmitt@im3.inserm.fr

⁶These authors contributed equally to the work.

⁷These authors share equally Co-senior authorship.

Received 4 October 2005; Revised 31 October 2005; Accepted 3 November 2005; Published online 12 December 2005.

Abstract

Natural killer cells are well known to play an important role in immune defense against tumor development and viral infections. To further characterize new functionally relevant structures in these cells, we studied a series of monoclonal antibodies that we have raised against the NK cell line YT. One of these antibodies previously described as AY19, recognizes a 85 kD surface glycoprotein. Here we report the identification of a new secreted isoform of protocadherin 15, PCDH15C, which represents a potential associated protein for p85. Importantly, whereas protocadherins are absent from the surface of normal hematopoietic cells, we describe, for the first time, that PCDH15 is expressed in cytotoxic tumor-derived T- and NK-cell lines as well as in biopsies of nasal NK/T-cell lymphomas.