A method of detecting neuroblastoma in human bone marrow by means of two monoclonal antibodies PI 153/3 and KE2.

A system is described to detect neuroblastoma (NBL) tumor cells in human bone marrow. The technique exploits the findings that NBL cells have little or no HLA antigen on the surface. Two monoclonal antibodies are used, PI153/3, IgM class, recognizes NBL and some pre-B lymphocytes and KE2 IgG class recognizes HLA. Two second antibodies are used, rhodamine-labeled anti-IgM and fluorescein-labeled anti-IgG. By means of fluorescence microscopy the neuroblastoma cells are labeled with rhodamine only, and the false + pre-B lymphocytes are double labeled with both rhodamine (Rh) and fluorescein (FI) since they are HLA+ and react with KE2. This method has been used to screen the marrow of 24 patients on 40 occasions and 64 laboratory preparations. It is possible to detect NBL cells at a concentration of 1:1000 marrow cells. The advantage of the technique is the fact that false positive cells can be defined because they have HLA surface antigen which neuroblastoma cells do not express.