H2BC21 and lupus nephritis: In the next step, the critical peptide autoepitopes recognized by lupus nephritis-inducing Th cells were localized initially to be in the core histones of nucleosomes, at amino acid (aa) positions: 10-33 of H-2B, 16-39 and 71-94 of H4, and 85-102 of H3 (61).