Immunological detection and definition of minimal residual neuroblastoma disease in bone marrow samples obtained during or after therapy

Consensus criteria for sensitive detection of minimal neuroblastoma cells in bone marrow, blood and stem cell preparations by immunocytology and QRT-PCR: recommendations by the International Neuroblastoma Risk Group Task Force

Disseminating disease is a predictive and prognostic indicator of poor outcome in children with neuroblastoma. Its accurate and sensitive assessment can facilitate optimal treatment decisions. The International Neuroblastoma Risk Group (INRG) Task Force has defined standardised methods for the determination of minimal disease (MD) by immunocytology (IC) and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) using disialoganglioside G(D2) and tyrosine hydroxylase mRNA respectively. The INRG standard operating procedures (SOPs) define methods for collecting, processing and evaluating bone marrow (BM), peripheral blood (PB) and peripheral blood stem cell harvest by IC and QRT-PCR. Sampling PB and BM is recommended at diagnosis, before and after myeloablative therapy and at the end of treatment. Peripheral blood stem cell products should be analysed at the time of harvest. Performing MD detection according to INRG SOPs will enable laboratories throughout the world to compare their results and thus facilitate quality-controlled multi-centre prospective trials to assess the clinical significance of MD and minimal residual disease in heterogeneous patient groups.

Lacking immunocytological GD2 expression in neuroblastoma: report of 3 cases

Immunocytological bone marrow assessment for contamination with neuroblastoma cells is based on their characteristic GD2 surface staining. Neuroblastoma without GD2 expression have been rarely and only after antibody therapy reported. Conventional cytology was performed using Pappenheim staining. For immunocytology, the APAAP method was utilized with the 14G2a anti-GD2 mouse monoclonal antibody. 7 x 10(5) cells on cytospin preparations were investigated. In 2003, 288 bone marrow samples from 191 neuroblastoma patients were investigated by cytology and immunocytology. Three cases demonstrated GD2 negativity on cytologically unambiguous neuroblastoma cells. Two female cases (94 and 37 months of age) with stage 4 neuroblastoma had GD2 expressing neuroblastoma cells in bone marrow at diagnosis. At 2nd relapse 25 and 23 months after diagnosis and 8 months and 12 months after anti-GD2 antibody treatment (ch14.18), the bone marrow infiltrating neuroblastoma cells lacked GD2 staining. The third patient, a 63-month-old girl with bone marrow replacement by neuroblastoma cells showed at diagnosis a mixture of GD2-unstained tumor clumps and very weakly stained neuroblastoma cells. Neuroblastoma cells may lack GD2 expression at diagnosis and at recurrence. This observation has diagnostic and therapeutic implications.

Differential diagnosis based on immunological-phenotyping in suspected malignant bone marrow involvement in childhood

The diagnostic value of immunophenotyping (IP) as a first-line diagnostic method in diseases that infiltrate the childhood bone marrow (BM) or mimic infiltrated BM was examined. Two hundred and fifty unselected BM samples from 250 children suspected to have a malignancy infiltrating their BM were evaluated by means of IP and conventional morophological-cytochemical (MC) studies. We applied the alkaline phosphatase anti-alkaline phosphatase method for IP using a panel of monoclonal antibodies (Mabs) against leukocyte-associated antigens, neuroectodermal antigens, and intermediate filament antigens. Four cases of neuroblastoma, two cases of Ewing sarcoma, and one case of rhabdomyosarcoma were diagnosed by IP but not by MC studies. In nine cases of acute leukemia bone marrow blasts could not be ascribed to a specific lineage on the basis of blast morphology or histochemistry. Eight samples without morphological evidence of malignant infiltration revealed an increased percentage of immature B cell precursors (CD10+, TdT+) suggesting acute lymphoblastic leukemia. None of these children has developed malignant lymphoproliferative disease. Our data suggest that the immunological evaluation of BM in childhood is highly capable of discriminating between different malignant populations but it does not recognize malignancy and therefore supplements but cannot replace conventional methods for diagnosis.

Monoclonal antibodies against neuroblastoma. Production and preliminary characterization of their specificity

Neuroblastoma (NB) is a common childhood tumor that originates from neuroblasts of the neural crest. In this paper we will describe the production of murine monoclonal antibodies (mAbs) to human NB cell lines. The hybridomas were selected by ELISA and immunofluorescence for antibody binding to multiple human neuroblastoma cultured cell lines, but not to hematopoietic cells and leukemic cells. The mAbs were characterized in terms of their ability to bind to human cell lines and tissues. The IgG2a and IgG2b mAbs may prove useful in the diagnosis of therapy of neuroblastoma.