| Abstract
| - Two tumour cell clones, 6D1 and 4C2 cells, which are defective both in the major histocompatibility gene complex (MHC) class I expression and in the endogenous antigen presentation, are recovered with interferon (IFN)-γ treatment. The present study describes the ultrastructure of these cells by using scanning and transmission electron microscopy in relation to the effect of IFN-γ treatment. The general morphology of these cells was found to be similar to each other and comparable to that of a tumour cell clone, 4A1 cells, of the same origin, normal in MHC dass I expression; they exhibited a fibroblast-like appearance and had many blebs on all the cell surfaces, with desmosome-like junctions between cells. On IFN-γ treatment, surface fine blebs appeared less, and mitochondria became more densely stained. Expression of MHC class I molecules on the cell surface was much higher in the IFN-γ treated 6D1 and 4C2 cells than in untreated cells, when estimated by immunoelectron microscopy. The addition of an epitope peptide to these cells did not enhance the class I expression, which differed from other antigen presentation-defective cells such as RMA-S cells, nor change the cell surface morphology.
|
