Activated lymphoid cells in human gliomas: morphofunctional and cytochemical evidence

To study defensive infiltrating cells, smear preparation from 20 fresh gliomas and autologous normal peritumoural brain tissue, used as control, were analysed. May-Grünwald Giemsa staining and cytochemical reaction markers of cellular functions [acid phosphatase (AP), dihydrofolate reductase (DHFR), dipeptidilpeptidase (DAP IV) and serine esterase BLT-dependent (SE)], were employed to characterize the cells. The extent of the leukocytic infiltration and the percentage of activated lymphocytes ("hand mirror" shape lymphocytes: HMS; lymphocytes binding tumor: LBT) were also studied. In addition serum levels of T cell growth factor interleukin-2 (IL-2) and of the soluble IL-2 receptor (sIL-2R) were determined in the affected patients. In tumoural imprints, mostly in astrocytomas, we observed an increased percentage of DHFR and DAP IV positive lymphocytes, of HMS lymphocytes and of lymphocytes binding tumoral cells. Serum levels of IL-2 were significantly increased in all patients whilst sIL-2R levels, were high only in glioblastoma. These findings indicate that in malignant gliomas there is stimulation of the immune system as witnessed by the presence of activated cells inside tumor tissue and soluble activating factors in serum.