In situ hybridization analysis of the age-associated decline in IL-2 mRNA expressing murine T cells.
Only a small decrease in the number of L3T4- cells was observed in the Con A-stimulated splenocyte cultures of old mice as compared to young, which cannot account for the threefold decrease in IL-2 production. Northern and dot blot analysis of RNA from splenocytes containing equivalent numbers of L3T4+ cells from young and old mice showed that cells from old mice express less IL-2 mRNA after mitogenic stimulation than cells from young mice. Direct analysis by in situ hybridization of stimulated splenocytes from young and old mice then showed approximately a threefold decrease in the percentage of IL-2 mRNA expressing cells in the spleens of old mice as compared to young (8.7 +/- 4.1% old; 28.7 +/- 11.7% young). The average level of expression of IL-2 mRNA was not significantly different between cells from young and old mice; however, there were approximately 40% fewer cells expressing an intermediate to high amount of IL-2 mRNA in old mice as compared to young (26.3% vs 41.8%). These data suggest that the decrease in IL-2 production with age is associated primarily with a decrease in the frequency of IL-2 mRNA-expressing cells in old mice, especially in those cells expressing intermediate to high levels of IL-2 mRNA.
Department of Microbiology, UCLA School of Medicine 90024.
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Fong
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Makinodan
D000375:Aging / Q000276:immunology*; D000818:Animals; D015152:Blotting, Northern; D003208:Concanavalin A / Q000494:pharmacology; D005786:Gene Expression Regulation; D007376:Interleukin-2 / Q000096:biosynthesis*; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000032:analysis*; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000145:classification / Q000378:metabolism*
D007376:Interleukin-2; D012333:RNA, Messenger; D003208:Concanavalin A