Immunohistochemical detection of two small cell lung carcinoma-associated antigens defined by MAbs F12 and 123C3 in bronchoscopy biopsy tissues.

We have studied MAbs* for their ability to detect SCLC and differentiate this tumor type from the other lung tumor histotypes in cryostat sections of biopsy specimens taken at bronchoscopy from patients with suspected primary lung tumor disease. MAb F12, specific for the ganglioside fucosyl-GM1, reacted with 58% of the cases with SCLC (n = 19) and with less than 3% of those with non-SCLC (n = 38). MAb 123C3, specifically reactive with NCAM, reacted with 78% of the SCLC cases (n = 23). With this MAb no positive staining was seen in the non-SCLC cases (n = 41). None of the two MAbs reacted with tissue sections without tumor. In combined analysis with MAbs F12 and 123C3, all SCLC cases (n = 15) were positive with either and 47% with both of the MAbs. Our results show that both MAbs F12 and 123C3 are highly specific for SCLC in bronchoscopic biopsy tissue specimens, whereas the sensitivity for this histotype tends to be higher with MAb 123C3 than with F12 (P = 0.14). When used in combination, all SCLC cases could be identified. These MAbs may therefore be valuable as complements to current histopathologic characterization and differentiation of lung cancer.