Effects of transpupillary thermotherapy on immunological parameters and apoptosis in a case of primary uveal melanoma

Transpupillary thermotherapy (TTT) is a new treatment modality for uveal me lanoma. We studied whether application of TTT influences the immunogenicity of the tumour cells in vivo or the expression of molecules related to apop tosis. Immunohistochemistry using monoclonal antibodies directed against HL A molecules, HMB45, P53, Fas ligand (FasL), Fas, Bcl-2 and tumour-infiltrat ing cells was applied to sections of an enucleated eye containing a uveal m elanoma that received TTT 1 week before enucleation. The innermost part of the tumour which had been exposed directly to the laser treatment showed no staining for HLA antigens, nor for Fas or Fast epitopes. The intermediate part of the tumour showed a wet necrosis and HLA expression similar to the expression in the peripheral tumour, A large number of macrophages were obs erved in the necrotic as well as the intact tumour tissue, especially borde ring the wet necrotic area. Fast and Bcl-2 were only expressed in the viabl e, outer part of the tumour. This immunological evaluation of one case of u veal melanoma treated with TTT revealed that TTT may not only have a direct destructive effect on the primary tumour, but may also influence the immun ogenicity of uveal melanoma cells, induce infiltration of macrophages into the tumour, and induce apoptosis. The presence of many macrophages suggests that they play a role in the removal of the TTT-treated tumour tissue by p hagocytosis. (C) 1999 Lippincott Williams & Wilkins.