Events occurring after dissociation of B2m, based on the previous reports (Demaria et al. [11,12,13], Elliott et al. [14,15], Bix and Raulet, [17]). It has been well documented (Cerundolo et al. [16]) that the human mutant cell T2 expressing H-2Db HCs, carrying 9 amino acid peptides, and complexed with human B2m, forms stable complexes with half-life > 110 h at 4 °C, 39 h at 22 °C, and 3 h at 37 °C. They have also shown that small increases in the length of the peptide greatly reduce the half life (t½ to about 1–10 h at 4 °C). The transformation of conformed HC to non-conformed HC and the cleavage of both conformed and non-conformed HC by MMPs and proteolytic degradation of B2m and HC (Demaria et al. [11,12]; Elliot, [14]). Proteolytic modifications of B2m in sera are based on Nissen et al. [18,19].