Reactivity of monoclonal antibodies with ganglioside antigens in human small cell lung cancer tissues

Gangliosides on tumor cells have been suggested as potential target antigens for specific immunotherapy in Various types of cancer including small cell lung cancer (SCLC). In this study we have compared the expression of three gangliosides that have been described as tumor-associated antigens, FucGM1, GM2 and GD3 in SCLC tissue specimens collected at autopsy, using a double-layer immunofluorescence staining method and specific monoclonal antibodies (Mabs) directed against these ganliosides. We found expression of FucGM1, GD3 and GM2 in approximate to 70% (n = 20), 60% (n = 15) and 40% (n = 20) of SCLC tissue specimens, respectively. Lymph node metastases appeared to express less antigen than SCLC lesions at other sites (lung, brain and liver). Reactivity of Mab with > 75% of tumor cells in individual lesions was seen in 55% of specimens for anti-FucGM1, 20% for anti-GD3, and in no specimen with anti-GM2. Only Mab F12 reacted with > 75% of the tumor cells in all lesions from the same patient (five of eight cases). Our results indicate that FucGM1 is a relevant ganglioside antigen in SCLC. and suggest that specific immunotherapy involving more than one ganglioside antigen in SCLC should at least include FucGM1 and GD3. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.