{"doi":"10.1002/eji.70114","title":"<i>Ccl21a</i> , Rather Than <i>Ccl21b</i> , is Essential for Thymocyte Migration in Mouse","abstract":"Self-tolerance in T cells is a vital self-defense strategy for mammals to specifically respond to invading pathogens. During T cell development in the thymus, thymocytes migrate from the cortex to the medulla to sequentially acquire non-self-reactivity and self-tolerance. This cortex-to-medulla migration is regulated by CCR7-mediated chemokine signaling. Previous studies have identified CCL21 but not CCL19 as a functional ligand for this CCR7-dependent migration. CCL21 in the mouse is encoded by multiple genes, including CCL21Ser-encoding Ccl21a and several CCL21Leu-encoding genes, including Ccl21b. The importance of Ccl21a in thymocyte migration has been demonstrated, whereas the role of CCL21Leu-encoding genes remains unclear. By producing mice specifically deficient in Ccl21b, we show that Ccl21b plays little to no role in the cortex-to-medulla migration of developing thymocytes. CCL21Leu-encoding gene transcripts remain detectable even in the absence of Ccl21b, suggesting that Ccl21b is not a major source of CCL21Leu. We further show that the copy number of CCL21Leu-encoding genes is smaller than the currently estimated copy number in a public database. These findings underscore the predominant role of Ccl21a over Ccl21b in the mouse thymus.","journal":"European Journal of Immunology","year":2025,"id":549593,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9518,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1444314,"name":"Hitomi Kyuma","orcid":null,"position":1,"is_corresponding":false},{"id":1444315,"name":"Eri Otsu","orcid":null,"position":2,"is_corresponding":false},{"id":1443799,"name":"Shinichi Hayashi","orcid":"0000-0002-1673-3853","position":3,"is_corresponding":false},{"id":1443800,"name":"Tatsuya Takemoto","orcid":"0000-0003-1860-0269","position":4,"is_corresponding":false},{"id":314995,"name":"Yousuke Takahama","orcid":"0000-0002-4992-9174","position":5,"is_corresponding":false},{"id":314994,"name":"Izumi Ohigashi","orcid":"0000-0003-0017-6957","position":0,"is_corresponding":true}],"reference_count":24,"raw_metadata":null,"created_at":"2026-07-19T02:54:07.823422Z","pmid":"41420491","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}