Monoclonal antibody to ganglioside GQ discriminates between haemopoietic cells and infiltrating neuroblastoma tumour cells in bone marrow.

An immunological approach has been sought for the identification of minimal metastatic spread of neuroblastoma to bone marrow. Here we describe the reactivity of the monoclonal antibody A2B5 to human neuroblastoma cell lines and fresh tumour tissue. This reagent, raised against chick retinal cells, reacts with all human neuroblastoma lines assayed although quantitative differences in antigenic expression exist between cultures. Analysis of tumour cells in heavily infiltrated bone marrow aspirates indicates that only 70% of the samples reacted with A2B5, suggesting that the heterogeneity seen in the expression of antigen on cell lines is paralleled in fresh tumour material. A2B5 showed no reactivity to either a panel of human leukaemic cell lines or normal human bone marrow, although reactivity to an occasional leukaemic marrow aspirate was detected. We suggest that A2B5 could form part of a panel of monoclonal reagents necessary for detecting metastatic spread of all neuroblastoma cells to bone marrow. Such a group of reagents may be useful therapeutically in a programmed of autologous bone marrow transplantation for the removal of tumour cells prior to reinfusion of haemopoietic cells to patients receiving high-dose chemotherapy.