Role of mRNA stability in the different patterns of cytokine production by CD4⁺ cells from young and old mice

Abstract

SUMMARYCD4+ cells from young (3 months) and old (19 months) mice were stimulated by plate-bound anti-CD3 monoclonal antibody (mAb) alone or also by soluble anti-CD28 mAb. Supernatants were analysed by enzyme-linked immunosorbent assay ( ELISA) to determine cytokine concentrations. Total RNA was extracted from cells, reverse transcribed and the cDNA amplified by polymerase chain reaction (PCR) to evaluate the amount of specific mRNA. The results indicate that anti-CD3 alone is not sufficient to induce interleukin-2 (IL-2) production in CD4+ cells from both young and old mice. However, anti-CD28, together with anti-CD3 mAb, induces a much higher production of IL-2 in CD4+ cells from young as compared with old mice. Conversely, interferon-c (IFN-c) production is also induced by anti-CD3 alone and is higher in CD4+ cells from old as compared with young mice. Upon addition of anti-CD28 mAb, IFN-c production increases in both groups, but it remains much higher in old than in young mice. Also the production of IL-4 and IL-10 is induced by anti-CD3 mAb but it is increased by the addition of anti-CD28 mAb. CD4+ cells from old mice produce more IL-4 and IL-10 as compared with cells from young mice. The amounts of cytokine specific mRNA in CD4+ cells from young and old mice parallel the cytokine levels in culture supernatants. Results on the mRNA turnover indicate that when CD4+ cells are stimulated by anti-CD3 or costimulated also by anti-CD28 mAb, the IFN-c, IL-4 and IL-10 specific mRNAs are more stable in old than in young mice, suggesting that mRNA stability has a relevant role in the different patterns of cytokine production.

CD28 Signaling in T Regulatory Precursors Requires p56lck and Rafts Integrity to Stabilize the Foxp3 Message

“…Stabilization of ARE-mRNA is mainly controlled by p38 MAPK, ERK, and PI3K signaling pathways, which can be all activated following the CD28 ligation (22)(23)(24)(25). Several other mRNA cytokine messages such as for IFN-␥, IL-4, and IL-10 are stabilized in CD4 T cells by CD28 stimulation (26).…”

High Accumulation of T Regulatory Cells Prevents the Activation of Immune Responses in Aged Animals

“…The reason for the accumulation of T reg cells in old mice is not yet understood. It has been demonstrated that there is shift from a Th1 to a Th2 response in aged mice (35), with an increased production of IL-10 (36), which may account in part for the high accumulation of T reg cells in these animals. Further studies are needed to completely understand the reason that T reg cells accumulate or expand in the old and how these populations relate to other immune-regulatory effects, such as cytokines, homeostasis, and APCs, and determine their specificity.…”

CTLA‐4 Engagement Inhibits Th2 but not Th1 Cell Polarisation

“…Cytokines were titrated in culture supernatants by sandwich ELISA as already described (Pioli et al, 1998). The reference straight line obtained by plotting the absorbance versus the standard cytokine concentrations was used to calculate cytokine concentrations in the supernatants.…”