As another example, a study using tissues from human study participants used HLA- B*57 tetramers loaded with MART (ELAGIGILTV), a peptide from melanoma protein, to serve as a negative control for FITC-labeled HLA- B*57 HIV-1 Gag IW9 (ISPRTLNAW) or QW9 (QASQEVKNW) tetramers during detection of HIV-specific tissue-resident CD8+ T cells within the gastrointestinal tract in a chronic infection [27]. Here, CD8A is linked to melanoma.