Cytofluorographic evidence that thymocyte dipeptidyl peptidase IV (CD26) activity is altered with stage of ontogeny and apoptotic status

✍ Scribed by Phillip Ruiz; Mehdi Nassiri; Bernard Steele; Ana L. Viciana

• Book ID: 102651489
• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 866 KB
• Volume: 23
• Category: Article
• ISSN: 0196-4763
• DOI: 10.1002/(sici)1097-0320(19960401)23:4<322::aid-cyto8>3.0.co;2-i

✦ Synopsis

CD26 is a multifunctional molecule implied to have a variety of roles in the immune response including its activity as a membrane exopeptidase (Dipeptidyl peptidase IV) which cleaves several protein molecules. In order to further define the expression and functional activity of ~~2 6 in the developing thymus, we utilized a nondisruptive, cytofluorogenic assay which allowed simultaneous measurement of DPP IV activity with a fluorochrome-conjugated peptide substrate and surface staining of the T lymphocyte lineage antigens CD4 and CD8. Neonatal and adult murine thymi were examined using the three-color assay and significant differences in DPP N activity were found among the thymocyte subsets defined by their CD4/ CD8 phenotype. Single-positive cells bore higher activity than CD4-/CD8-cells and neonates had higher activity than adults. Thymocytes with characteristics consistent with apoptotic cells expressed higher DPP N activity. Thus, DPP IV appears to be upregulated both as thymocytes mature and among thymocytes which are undergoing programmed cell death. These results suggest that CD26 is ontogenically controlled during T cell maturation and may play a role in thymic deletion of emerging Clones.