Identification and Quantification of a Naturally Presented Peptide As Recognized By Cytotoxic Lymphocytes-t Specific for An Immunogenic Tumor Variant

The target antigen recognized by H-2K(d)-restricted cytotoxic T lymphocytes (CTLs) specific for a mutagen-induced antigen on DBA/2-derived tumor P815 was identified as the product of a normal cellular gene encompassing a point mutation. Using synthetic peptides, the epitope recognized by these CTLs was narrowed down to be contained within the undecamer KYQAVTTTLEE, incorporating the point mutation. The allele-specific peptide motif for H-2K(d) molecules allowed us to predict the peptide naturally presented by the tumor cells to be the nonamer KYQAVTTTL. Isolation of the natural tum--specific peptide from P198.3 tumor cells and biochemical comparison with the synthetic nonamer confirmed the prediction. This natural nonapeptide is represented by approximately 1 00 copies per tumor cell

The Missing Link? U.S. Policy and the International Dimensions of Authoritarian Resilience in the Arab World

In contrast to the hopes of some US observers, the so-called 'Baghdad Spring' of early 2005 did not mark the beginning of an era of sustained political reform in the Middle East. In an attempt to explain the resilience of authoritarian governance in the region, this article aims to demonstrate the insufficiencies of external democratisation efforts that rely on a crude reading of the 'modernisation' school of thinking and ignore the insights of the 'transition' school with regard to the international dimensions of democratisation. Case studies of Egypt and Saudi Arabia, two countries sharing close strategic relationships with the United States yet differing in the socio-economic foundations of authoritarianism and experiences with managing external and domestic calls for political reform, demonstrate that the unwillingness of the United States to condition its support for regional partners on human rights concerns constitutes one of the main reasons for the Arab world's 'democratic exception'