Position dependent differences between immunogenic and non-immunogenic peptides.

For peptides presented on HLA class I molecules in HLA transgenic mice that were either known to be immunogenic or non-immunogenic (see Methods), amino acids were counted per position. The 20 counts for immunogenic and non-immunogenic pMHCs were compared per position using the Kullback-Leibler divergence. A Fisher's test (Methods) was done to determine if the distributions were significantly different (* p<0.05; **p<0.01). †Position 1 is not an anchor in every HLA molecule, nonetheless it is an anchor in most pMHCs wherefore the divergence cannot be estimated at this position.