Immunofluorescence study of lymphocytic infiltration in gliomas. Identification of T-lymphocytes

Five human brain tumours (3 glioblastomas and 2 astrocytomas) and 5 rat brain tumours induced in Sprague--Dawley animals by systemic administration of N-methyl-N-nitrosourea (3 pleomorphic gliomas and 2 mixed gliomas) were studied. The human brain tumours were surgical specimens excised from patients with no cranial surgery prior to their disease. The experimental brain tumour had been adapted to tissue culture, propagated in vitro and then transplanted to immunocompetent and immunodeficient rats of the same stock. The above-described material was selected in consideration of the mononuclear cell infiltrates occurring in these tumours. Frozen sections of human and rat gliomas, the latter both primary and transplanted, were prepared and investigated as to the presence of T-lymphocytes within the mononuclear round cell infiltrates. This was done with the indirect immunofluorescence method using rabbit antisera against man and rat T-lymphocytes. With this technique a variable percentage of T-lymphocytes was demonstrated in the cell infiltrates of human and rat gliomas alike. The tumour transplanted in thymectomized rats showed only isolated, scattered, positive-reacting cells, i.e., cells recognizable as T-lymphocytes by the above method. The results can be interpreted as circumstantial evidence for the occurrence of tumour-specific and/or tumour-associated antigens in the parenchymal cells of spontaneous and chemically-induced gliomas.