JLP5B9: new monoclonal antibody against polysialylated neural cell adhesion molecule is of value in phenotyping lung cancer

Non-small-cell lung cancer (NSCLC) is currently one of the most prevalent m alignant tumors. It displays a wide variety of phenotypes which includes ne uroendocrine markers commonly found on small-cell lung cancers (SCLC) such as the neural cell adhesion molecule (NCAM) and in particular its highly po lysialylated isoform, embryonic NCAM (eNCAM). NSCLC with neuroendocrine dif ferentiation may represent a subset of tumors whose cells have a more aggre ssive biological behavior. A tumor marker that distinguishes this latter su b-type could be of clinical relevance. Accordingly, we have raised a monocl onal antibody of the IgM type (JLP5B9) directed against capsular polysaccha rides of N. meningitidis B which bears polysialic acid groups. We have demo nstrated that JLP5B9 recognizes eNCAM with high affinity and that it is spe cifically directed against the polysialic acid moieties of NCAM. JLP5B9 was also found to react with human SCLC, NSCLC and neuroblastoma cell lines. W e then used JLP5B9 as a specific probe for the detection of tissue eNCAM an d found that it was expressed on up to 20% of tumor cells obtained from 5 o ut of 13 patients with NSCLC. This mAb deserves further investigation to ev aluate its potential as a tool for serodiagnosis of lung cancer. (C) 2000 E lsevier Science B.V. All rights reserved.