[Detection of carbohydrate antigens of malignant cells in sputum with panel of monoclonal antibodies].

Serum tumor markers are useful for post-operative follow up, however, they are not necessarily useful for early stage diagnosis. Because the lesion is so small that it is unable to detect a tiny amount of their molecules in serum. If we could detect those antigens directly in cells from cytological specimens, it would provide a new diagnostic method for early stage cancers. The expression of carbohydrate antigens were examined with panel of specific anti-carbohydrate monoclonal antibodies (MAbs) on cytological specimens of sputum. In total, 146 sputa were collected in Sacomano's solution; 69 malignant cases (35 squamous cell carcinomas, 13 adenocarcinomas and 21 other primary lung cancers), 19 benign cases (pneumonia and bronchitis) and 58 borderline-malignancy cases which were defined by the standard of Japan Society of Lung Cancer. After removing mucus, the cells were stained with Vector's ABC method. Evaluation was performed by counting positively-stained cells among benign or atypical cells. As we examined previously in lung cancer tissue sections, there was statistical significance of frequency of positive stain between malignant and benign cases especially in MAbs AH6, THK2, SH1 and SNH3. Borderline malignancy gave intermediate value which means certain number of cells with cancerous biochemical character are mixed in the borderline specimens. In most cases, cell membrane was positively stained and sometimes, cytoplasm. Although the high sensitivity was observed in AH6 and SNH3, their specificity was lower than that of SH1, and visa versa. Those results indicate that the combination of anti-carbohydrate MAbs is useful for cytological diagnosis of lung cancer.