Ruiz P, Nassiri M, Steele B, Viciana A L
Department of Pathology, University of Miami School of Medicine, FL 33101, USA.
Cytometry. 1996 Apr 1;23(4):322-9. doi: 10.1002/(SICI)1097-0320(19960401)23:4<322::AID-CYTO8>3.0.CO;2-I.
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 CD26 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 IV 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 IV 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.
CD26是一种多功能分子，在免疫反应中具有多种作用，包括作为膜外肽酶（二肽基肽酶IV）的活性，该酶可切割多种蛋白质分子。为了进一步确定CD26在发育中的胸腺中的表达和功能活性，我们采用了一种非破坏性的细胞荧光测定法，该方法允许同时使用荧光染料偶联的肽底物测量DPP IV活性，并对T淋巴细胞谱系抗原CD4和CD8进行表面染色。使用三色测定法检查新生和成年小鼠胸腺，发现在由其CD4/CD8表型定义的胸腺细胞亚群中，DPP IV活性存在显著差异。单阳性细胞的活性高于CD4-/CD8-细胞，新生儿的活性高于成年人。具有与凋亡细胞一致特征的胸腺细胞表达更高的DPP IV活性。因此，随着胸腺细胞成熟以及在经历程序性细胞死亡的胸腺细胞中，DPP IV似乎都被上调。这些结果表明，CD26在T细胞成熟过程中受到个体发育的控制，并且可能在新出现克隆的胸腺缺失中发挥作用。
