Detection of SCLC metastatic cells in bone marrow by means of the monoclonal antibody MLuC1

Many monoclonal antibodies (Moabs) have been demonstrated to be useful as diagnostic tools. We investigated the possibility of using Moabs to detect metastatic cells in vitro in the bone marrow from small cell lung carcinoma (SCLC) patients, either for staging the disease or in the perspective of bone marrow transplantation. The monoclonal antibody designated MLuC1 was selected for this application due to its strong and homogeneous reactivity on almost all the tested SCLC and its negativity on normal bone marrow cells. Among 30 bone marrow aspirates obtained from SCLC patients, 4 cases were found to be positive for presence of malignant cells with both conventional histology and immunofluorescence using MLuC1. Among the other histologically negative bone marrow MLuC1 reactive cells were found in 5 cases. The MLuC1-positive cases were monitored during and after chemotherapy and a progressive decrease in the number of bone marrow contaminating tumour cells was observed by MLuC1 immunofluorescence