| First Author | Li L | Year | 2004 |
| Journal | J Immunol | Volume | 172 |
| Issue | 5 | Pages | 2909-16 |
| PubMed ID | 14978093 | Mgi Jnum | J:88230 |
| Mgi Id | MGI:3029799 | Doi | 10.4049/jimmunol.172.5.2909 |
| Citation | Li L, et al. (2004) IL-12 inhibits thymic involution by enhancing IL-7- and IL-2-induced thymocyte proliferation. J Immunol 172(5):2909-16 |
| abstractText | IL-12 has been reported to affect thymic T cell selection, but the role of IL-12 in thymic involution has not been studied. We found that in vivo, IL-12b knockout (IL-12b(-/-)) mice exhibited accelerated thymic involution compared with wild-type (WT) B6 mice. This is characterized by an increase in thymocytes with the early development stage phenotype of CD25(-)CD44(+)CD4(-)CD8(-) in aged IL-12b(-/-) mice. Histologically, there were accelerated degeneration of thymic extracellular matrix and blood vessels, a significantly decreased thymic cortex/medulla ratio, and increased apoptotic cells in aged IL-12b(-/-) mice compared with WT mice. There was, however, no apparent defect in thymic structure and thymocyte development in young IL-12(-/-) mice. These results suggest the importance of IL-12 in maintaining thymic integrity and function during the aging process. Surprisingly, in WT B6 mice, there was no age-related decrease in the levels of IL-12 produced from thymic dendritic cells. Stimulation of thymocytes with IL-12 alone also did not enhance the thymocyte proliferative response in vitro. IL-12, however, provided a strong synergistic effect to augment the IL-7 or IL-2 induced thymocyte proliferative response, especially in aged WT and IL-12b(-/-) mice. Our data strongly support the role of IL-12 as an enhancement cytokine, which acts through its interactions with other cytokines to maintain thymic T cell function and development during aging. |
