Immunocytochemical demonstration of bombesin immunoreactivity in small cell carcinoma of the lung. A methodological study and review of the literature

Bombesin-like immunoreactivity (BLI) has been detected in cell lines of human small cell carcinoma of the lung (SCCL) and in tumors grown in nude mice. Based on these observations, much interest was devoted to gastrin-releasing peptide (GRP, bombesin) as a potential immunocytochemical diagnostic marker in the primary histopathologic diagnosis of SCCL as well as in the diagnosis of metastases. The present communication deals primarily with methodological problems concerning the application of bombesin/GRP immunocytochemistry to surgical material from patients with SCCL. Two antisera against GRP were used. Paraffin-embedded material was compared to cryostat sections. The study concluded: (1) paraffin embedding severely compromised the bombesin/GRP immunoreactivity to the antibodies available; (2) relatively few SCCL tumors ( 6 15 = 40% based on cryostat sections) stained for GRP. From the present study and a review of the literature it seems justified to conclude that the demonstration of bombesin/GRP in SCCL in surgical material is connected with great difficulties, and bombesin/GRP immunocytochemistry, when used alone, does not seem to be a good marker for the histopathologic diagnosis of SCCL.