Cytotoxic monoclonal antibody to a human leiomyosacoma

A monoclonal antibody produced by the hybridoma technique against a human leiomyosarcoma was highly cytotoxic in dilutions of 1:64 000 to the original tumour cells. The antibody was unreactive with most normal cells (lymphocytes, 120 donors; spleen cells, 73/75; monocytes, 16; granulocytes, 25; platelets, 12; red cells, 11) and could not be absorbed out by smooth muscle from the small intestine or by spleen cells. Its specificity for the tumour was high since it did not react with cells from 40 patients with leukaemia, from 8 patients with other tumours, and from 7 cultured tumour lines. The only other cell that it reacted with (at 1:4000 dilution) was line 8402, a T acute lymphocytic leukaemia line. This monoclonal antibody may be suitable for therapeutic trials.