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The immunosuppressive effects of irradiation are well known; however, under certain circumstances irradiation also augments the local immune response by as yet undefined mechanisms. Because of the importance of HLA class I antigen in immune regulation and the fact that killing of tumor cells by cytotoxic T cells is HLA antigen-restricted, the authors studied HLA class I antigen expression in eight glioblastomas multiforme, four meningiomas, and four medulloblastomas. Twenty fragments of each tumor specimen were placed in short-term cultures immediately after resection. For each tumor, control Sample 1 was not irradiated. Sample 2 was irradiated on Day 1, and two groups of the remaining pieces of each tumor (specimens 3 to 10) were irradiated on two consecutive days. Escalating radiation doses were given, starting at 200 cGy/day for Sample 2 up to 1000 cGy/day for Sample 10. The total dose range was 200 to 2000 cGy. Corresponding nonirradiated tumor fragments served as controls. Four hours after irradiation, each sample was processed and stained for HLA class I antigen using the immunoperoxidase technique. The tumor cells were intensely stained in nonirradiated glioblastomas and meningiomas, whereas no staining was observed in medulloblastomas. In four of the eight glioblastomas and in all four meningiomas, irradiation augmented HLA class I antigen expression compared to controls. This effect was dose-dependent and was maximum in the 1200 cGy-treated specimens. No change was observed in the other four glioblastomas or in the medulloblastomas. The data suggest that irradiation does not decrease and may even induce HLA class I antigen expression in some brain tumors. This may be one of the mechanisms by which immunotherapy operates after irradiation. Further studies are required to elucidate optimum radiation doses and fractionation as well as optimum timing of immunotherapy.

Background. The orbit is rarely a secondary site of lymphoma dissemination, and only few reports exist on the course and characteristics of involvement in these sites. Methods. The authors retrospectively reviewed the records of 187 consecutive patients with systemic non‐Hodgkin's lymphoma (NHL) diagnosed and treated at Beilinson Medical Center between 1986 and 1992. Results. Ten patients (5.3% of those with NHL) had orbital or adnexal involvement or both. Histologically, six had intermediate‐grade lymphoma, three had diffuse small cleaved cell lymphoma, and one had nodular small cleaved cell lymphoma. In all 10 patients, the lymphoma was widespread, and in 6, there were two or more other extranodal sites of involvement, mainly, bone marrow (six) and skin (three). The orbital involvement was found either at presentation or as late as 53 months after primary diagnosis. Various therapeutic approaches were chosen, from local orbital irradiation to different mild to aggressive chemotherapeutic protocols. Complete regression of the orbital or adnexal involvement or both was observed in 9 of 10 patients, but in 6 the systemic disease either persisted or recurred at other sites. Conclusions. Orbital or adnexal involvement or both by NHL may appear at any time during the course of the disease. It responds well to either chemotherapy or radiation therapy with prolonged local remission. The results of this study strongly suggest that every patient with NHL in whom any periorbital or orbital mass, ptosis, proptosis or lid edema develops should be suspected of having orbital lymphoma involvement until proven otherwise.

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