New method for quantitative analysis of GD2 ganglioside in plasma of neuroblastoma patients.

Neuroblastoma, the most common extracranial solid tumour of childhood, is a malignancy of unknown origin and non-specific symptoms. One of the markers of the disease is GD2 ganglioside (disialoganglioside), which is abundantly expressed on the surface of neuroblastoma cells. Gangliosides are known to be shed by tumour cells and this phenomenon can be significant in cancer progression as they inhibit a number of immune responses both in vitro and in vivo. In search for novel markers useful in monitoring and prognosis of neuroblastoma, we developed and validated a new quantitative method of GD2 ganglioside analysis in human blood plasma. We evaluated the level of gangliosides in blood serum of 34 neuroblastoma patients using high-performance liquid chromatography. The technique was used to detect fluorescently labelled oligosaccharides derived from serum glycosphingolipids by enzymatic digestion with ceramide glycanase. The developed method allowed determination of GD2 concentrations at the picomole level and required only 40 microl of plasma, which should be particularly useful when the quantity of clinical material is limiting. Moreover, this method can be applied to study concentration of other gangliosides, as shown for GD3 ganglioside. Analysis of plasma samples from the 34 neuroblastoma patients did not reveal any correlations between the concentration of GD2 ganglioside and clinical parameters, including the results of therapy; it showed, however, that the concentration of GD2 ganglioside in the plasma of neuroblastoma patients decreased substantially in the course of treatment.