RESUMO
INTRODUCTION: The identification of molecules expressed selectively on the surface of retinoblastoma cells would allow applying targeted therapies. The Ganglioside, N-Glycolyl-GM3 (NeuGc-GM3), is an attractive candidate, as it has been detected in other paediatric neuroectodermic tumours, and it is not expressed in human normal tissues. The 14F7 antibody recognizes specifically the ganglioside NeuGc-GM3. PURPOSE: To characterize the expression of NeuGc-GM3 in retinoblastoma cell lines and in retinoblastoma tumours using the 14F7 monoclonal antibody. METHODS: We studied WERI-Rb1 and Y79 cell lines, 24 retinoblastoma primary tumours from unilateral and bilateral cases and two bone marrow biopsies from metastatic retinoblastoma. Tumours were classified into three groups: non-invasive (n = 13), invasive (n = 9) and metastatic (n = 2). Three eyes enucleated because of non-tumoural conditions were used as controls. Cell lines and tumour sections were studied by immunohistochemistry using the 14F7 antibody. NeuGc-GM3 expression was evaluated by analysing the percentage of positive tumoural cells and the staining intensity. These parameters were analysed comparatively among the three groups. RESULTS: Both retinoblastoma cell lines showed immunoreactivity to NeuGc-GM3 but WERI-Rb1 presented higher intensity than Y79. All the tumours studied showed strong immunoreactivity to NeuGc-GM3 with no significant differences among groups. In both bone marrow specimens, NeuGc-GM3 immunoreactivity was observed in retinoblastoma cells. In bilaterally enucleated cases, NeuGc-GM3 immunoreactivity was not altered before and after chemotherapy. Non-tumoural retinas were negative. CONCLUSIONS: NeuGc-GM3 is highly expressed in retinoblastoma cell lines, tumours and metastatic cells to the bone marrow, and it is not detectable in control eyes. There were no significant differences in the immunoreactivity to 14F7 among tumours from different disease stages. Its immunoreactivity did not change after chemotherapy.
Assuntos
Autoantígenos/análise , Gangliosídeo G(M3)/análogos & derivados , Neoplasias da Retina/química , Retinoblastoma/química , Anticorpos Monoclonais/imunologia , Linhagem Celular Tumoral , Gangliosídeo G(M3)/análise , Gangliosídeo G(M3)/imunologia , Humanos , Técnicas ImunoenzimáticasRESUMO
We report two cases of pleomorphic xanthoastrocytomas of the retina. The immunoreactivity to CD68, Fe (Pearls' technique), astrocytes (argentic technique), and antibodies to glial fibrillary acidic protein was tested in tumor cells. Both neoplasms contained cells immunoreactive for glial fibrillary acidic protein and CD68. These tumors, observed in the CNS, first reported by Kepes et al. were found in the retina as well-circumscribed masses with a cystic component. Many large pleomorphic cells contained vesicular and enlarged nuclei with a homogeneous eosinophilic cytoplasm, prominent nucleoli, and calcium deposits. Some cells had a markedly swollen lipidized cytoplasm, whereas others were spindle-shaped and contained multiple nuclei. These findings suggest that our two specimens have an astroglial lineage and are similar to pleomorphic xanthoastrocytomas of the CNS brain and spinal cord. Both reported cases were in female patients who were in their 20s and had glaucoma. After 10 years both are free of disease.