Binding specificity of two monoclonal antiglioma antibodies: immunocytochemical studies using a new tissue embedding technique.

The binding specificities of two monoclonal antiglioma antibodies (MAB) derived from hybrids GE2 and BF7 (Schnegg et al. 1981) were tested by indirect immunofluorescence (IF) and two immunoperoxidase (IP) methods. Studies were done on biopsies from 33 human CNS tumors, human derived glioma cells, and N-ethylnitrosourea-induced neurogenic rat cells in culture. The immunohistochemical reactions of MAB were investigated in snap-frozen tumor material, conventionally paraffin-embedded material, and tumors embedded in formol sucrose/gum sucrose/paraffin (FSGSP) by the new tissue processing technique of Bolton and Mesnard (1982), which preserves and enhances the antigenicity of tissues. The FSGSP processing offered a better immunocytochemical staining with MAB as compared to cryostat material, while the conventionally embedded paraffin sections of tumors did not stain at all. The binding of MAB revealed an affinity to both glial tumor cells and normal astrocytes. The techniques described are suitable for the identification of an astrocytic subpopulation within gliomas, and may improve the understaining of antigen expression in various stages of astrocytic dedifferentiation.