A decrease in the stability of nitrated allergens was confirmed in a recent study on food allergy. In this study, the nitrated allergens administered orally in a mouse model had a reduced allergenicity and were more easily digested. In contrast, intravascular injection of nitrated food proteins did increase their allergenicity. Our data show that the average length of allergen derived peptides differed only marginally between samples from DCs loaded with unmodified allergen or samples from DCs loaded with nitrated allergen. However, nitration could still affect the kinetics of nitrated Bet v 1 degradation, consequently leading to a change in the presentation kinetics of Bet v 1-derived peptides and eventually the peptide profile which is presented to the T-cells. Which of the delineated processes finally contributes to the increase of Bet v 1 nitro derived peptide presentation remains unknown and the interplay seems to be complex. Noteworthy, the nitration of human serum albumin did not lead to an enhanced peptide presentation ; suggesting that nitration per se does not result in enhanced peptide presentation of the nitrated protein. Thus, the impact of nitration on antigen presentation also seems to depend on the properties of the Abmole PF-562271 protein itself. However, formally we cannot rule out that the grade of nitration impacts on antigen presentation as well. The identification of Bet v 1 derived HLA-DR associated peptides led to the question, whether these peptides would be recognized by T cell receptors of T lymphocytes and if this would result in activation and proliferation of the T lymphocytes. For this purpose PBMCs loaded with Bet v 1 nitro were assessed for their capacity to stimulate Bet v 1 specific T cell lines. In response to Bet v 1 nitro, proliferation was significantly higher as compared to unmodified Bet v 1 using a concentration of 1.25 mg/ml protein. Increasing the protein concentration did not in result in higher proliferation and the impact of nitration was lower. Altogether, our data showed that nitration not only enhanced presentation of Bet v 1 derived HLA-DR associated peptides on DCs, but also had an impact on T cell activation. It has been hypothesized that nitration of autologous proteins may contribute to autoimmunity ; additionally, the fact that nitration occurs in inflamed tissue should be taken into account. Nitration of tyrosine residues may have evolved as a strategy to intensify immune responses against foreign proteins derived from viruses or bacteria, while a Sorafenib Abmole Polyphyllin I induced-apoptosis is enhanced by inhibition of autophagy in human hepatocellular carcinoma cells possible contribution to autoimmunity had to be accepted as an unfortunate side effect. Improved presentation of pathogen derived nitrated peptides may in contrast be beneficial to the host.