Fig. 5.

Formation of cryptic epitopes via a somatic mutation. A somatic mutation that causes amino acid replacement may create cryptic epitopes, which can be recognized as non-self and trigger autoimmune response. Top, normal protein digested by trypsin makes normal peptides that are supposed to have immunological tolerance. Bottom, if arginine is replaced by other amino acid, trypsin digestion may create cryptic epitopes that have no or incomplete immunological tolerance and trigger autoimmune response