Journal of Electron Microscopy 47(5): 495-503 (1998)
© 1998 Oxford University Press
Ultrastructure of murine tumour cell lines defective in MHC class I expression before and after interferon-
treatment
Department of Virology and Immunology Nasahara, Takatsuki, Osaka 569-1094, Japan
2Electron Microscopy Laboratory, Oska University of Pharmaceutical Sciences Nasahara, Takatsuki, Osaka 569-1094, Japan
3Department of Tumorigenesis, Medical and Education Center, Osaka University, School of Medicine Suita, Osaka 565-0871, Japan
*To whom correspondence should be addressed: 9-6 Miyanoshita, Hirakata, Osaka 573-0046, Japan. E-mail: nz6t-hsk{at}asahi-net.or.jp
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)-
treatment. The present study describes the ultrastructure of these cells by using scanning and transmission electron microscopy in relation to the effect of IFN- 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- 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- 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.
Keywords MHC class I, immunogolds, interferon (IFN)-, mitochondria, antigen presentation
Received 24 December 1997, accepted 2 March 1998