The loss of contacts between the peptide and the MHC molecule could lead to decreased stability of the peptide and subsequent changes in NPN3A presentation. To test this hypothesis, we performed a thermostability assay on both NP 366 and NPN3A bound to the H-2D b molecule. The NP 366 and NPN3A peptides are equally effective at stabilising H-2D b . The pMHC-I complex with the NP 366 wt peptide had a Tm of 51.860.7uC and D b NPN3A showed a comparable level of thermostability (Tm = 51.461uC), irrespective of the concentrations of the complex used for the assay. This suggests that the NPN3A mutation does not modify the stability of the pMHC-I complex when compared to the cognate epitope.