Differential Expression of NGF Receptors in Human Thymic Epithelial Tumors

Summary NGF receptor (TrkA and p75 NGFR ) expression was investigated in human thymuses, including normal thymuses, thymic hyperplasias, thymomas and thymic carcinomas. by RT-PCR. In normal thymuses, immunohistochemistry revealed a restricted TrkA-immunoreactivity to epithelial and interdigitated reticular cells, while only interdigitaded reticular cells were immunoreactive for p75 NGFR . Thymocytes were negative for both receptors. A switch from the normal TrkA positive-p75 NGFR negative phenotype to a TrkA negative-p75 NGFR positive phenotype was found in histologically aggressive epithelial cell tumors, suggesting that NGF and its receptors are potentially involved in thymus stroma organogenesis and proliferation.