RAS oncogenic proteins are frequently found mutated in human cancers, where they are known to be implicated in the tumoral process. Mutations occur preferentially at positions 12, 13 or 61. Identification of potential T cell epitopes is the first step to determine if RAS mutated proteins can generate tumor specific antigens which could be further used as targets for cancer immunotherapy protocols. We have investigated the capacity of synthetic wild-type and mutant RAS derived peptides encompassing positions 12 and 13 to bind to three frequent HLA-A alleles: HLA-A∗0201, HLA-A∗0301 and HLA-A∗1101. Binding was evaluated by two methods using TAP-defective cell lines: a cytometric assay based on HLA molecules stabilization at the cell surface, and an assembly assay detecting interactions between solubilized HLA molecules and peptides. Positive HLA binding was observed for two sets of synthetic peptides, one specific for HLA-A∗0201 allele (RAS 5–14), and the other one specific for HLA-A∗0301 and HLA-A∗1101 alleles (RAS 8–16). Interestingly, the different substitutions at positions 12 and 13 were not equivalent for HLA binding. These observations will be useful for the in vitro generation of restricted CD8+ T lymphocytes specific for mutated RAS proteins and recognizing tumoral cells expressing such RAS mutations.

Invasive mycoses are pre-eminent causes of morbidity and mortality in the allogeneic stem cell transplant setting. In spite of novel diagnostic modalities, the timely and specific identification of invasive mycoses still remains challenging. We analyzed the case history of 97 consecutive patients receiving 103 allogeneic stem cell transplants between January 2003 and October 2006 performed by a single team at 2 transplant centers in Budapest, Hungary. All patients with febrile neutropenia not responding to broad-spectrum antibacterial therapy received amphotericin B deoxycholate empirically. In cases of proven or probable invasive aspergillosis, intravenous voriconazole was instituted. Patients who failed to improve on initial therapy were treated with an antifungal combination, while responders were switched to oral voriconazole. A total of 38 patients died following allografting. Both centers had an autopsy rate of 100% due to central health care regulations. An infectious cause of death could be identified in 15 cases, invasive fungal disease being the most prevalent and accounting for 10 fatalities. Six patients died of invasive aspergillosis, while invasive candidiasis and mucormycosis led to a fatal outcome in 2 cases each. Despite the regular use of galactomannan antigen detections and imaging, an ante mortem diagnosis of proven/probable invasive fungal disease could only be established in 4 of 10 autopsy-verified cases (aspergillosis: 3, candidiasis: 1, mucormycosis: 0). In the remaining 6 patients, deep mycoses were missed clinically and were revealed only by postmortem histology. Present diagnostic and therapeutic strategies still seem to be suboptimal for the management of invasive fungal diseases in the high-risk allogeneic stem cell transplant population.