Enhanced expression of neuron-specific enolase (NSE) in pyothorax-associated lymphoma (PAL)

Pyothorax-associated lymphoma (PAL) is a B-cell lymphoma of mostly large cell type developing in the pleural cavity of patients with long-standing pyothorax. Neuron-specific enolase (NSE) is an enolase comprising gamma subunit and is located at high levels in neuronal and neuroendocrine cells, together with their neoplasias. Expression of NSE at protein and mRNA levels was examined in PAL and other types (non-PAL) of non-Hodgkin's lymphomas. In PAL, serum levels of NSE were elevated (5.32 to 168.0, mean 42.6 ng/ml) and tended to decrease after incisional biopsy followed by chemotherapy (2.38 to 195.5, mean 34.1 ng/ml). Two cell lines established from two cases of PAL produced and secreted NSE in the culture medium. Immunohistochemistry revealed that the positive rate for NSE staining in PAL (10 of 14 cases, 71.4%) was significantly higher than that in non-PAL cases (6 of 38 cases, 15.8%) (P<0.01). RT-PCR analysis showed that the expression levels of NSE mRNA in two cell lines and a biopsy sample from PAL were rather similar to those of the control samples from non-neoplastic lymph nodes. These findings suggest the posttranscriptional regulation of NSE in PAL. Thus, an elevation of serum NSE level in patients with chronic pyothorax may be an indicator of PAL development.