This peptide is amino acids 323 to 339 amidated fragment of ovalbumin (OVA), the H-2b-restricted OVA class II epitope. This peptide is recognized by many T cells because it contains multiple T cell epitopes. This OVA fragment contains a nested set of CD4+ T cell epitopes. OVA 323 to 339 can be presented by I-Ad in at least three binding registers. The residues 327 to 333 are critical for peptide binding to I-Ad.