MiR-493-5p inhibits Th9 cell differentiation in allergic asthma by targeting FOXO1.

The role of micro RNAs (miRNAs) in asthma remains unclear. In this study, we examined the role of miRNA in targeting FOXO1 in asthma. Results showed that miR-493-5p was one of the differentially expressed miRNAs in the PBMCs of asthmatic children, and was also associated with Th cell differentiation. The miR-493-5p expression decreased significantly in the OVA-induced asthma mice than the control groups. The miR-493-5p mimic inhibited the expression of the IL-9, IRF4 and FOXO1, while the inhibitor restored these effects. Moreover, the Dual-Luciferase analysis results showed FOXO1 as a novel valid target of miR-493-5p. According to the rescue experiment, miR-493-5p inhibited Th9 cell differentiation by targeting FOXO1. Then the exosomes in association with the pathogenesis of asthma was identified. Various inflammatory cells implicated in asthmatic processes including B and T lymphocytes, DCs, mast cells, and epithelial cells can release exosomes. Our results demonstrated that the DC-derived exosomes can inhibit Th9 cell differentiation through miR-493-5p, thus DC-derived exosomal miR-493-5p/FOXO1/Th9 may serve as a potential therapeutic target in the development of asthma.

CD4+ T cell phenotypes in the pathogenesis of immune thrombocytopenia.

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by low platelet counts due to enhanced platelet clearance and compromised production. Traditionally, ITP was regarded a B cell mediated disorder as anti-platelet antibodies are detected in most patients. The very nature of self-antigens, evident processes of isotype switching and the affinity maturation of anti-platelet antibodies indicate that B cells in order to mount anti-platelet immune response require assistance of auto-reactive CD4+ T cells. For a long time, ITP pathogenesis has been exclusively reviewed through the prism of the disturbed balance between Th1 and Th2 subsets of CD4+ T cells, however, more recently new subsets of these cells have been described including Th17, Th9, Th22, T follicular helper and regulatory T cells. In this paper, we review the current understanding of the role and immunological mechanisms by which CD4+ T cells contribute to the pathogenesis of ITP.

SGK1 enhances Th9 cell differentiation and airway inflammation through NF-κB signaling pathway in asthma.

This study aimed to explore the effect of Sgk1 on Th9 differentiation and the underlying mechanism in asthma. The asthmatic mouse model induced by ovalbumin (OVA) and CD4+T cells which were cultured with TGF-ß, IL-2, IL-4, and anti-IFN-γ were applied in vivo and in vitro, respectively. Flow cytometry, quantitative real-time PCR (qRT-PCR), and ELISA were performed to detect T-helper 9 (Th9) cells, IL-9 expression, and IL-9 release. Western blot was performed to examine phosphorylated(p)-IKKα, p-IκBα, p-p65, and IRF4 levels. Hematoxylin/eosin (H&E) staining was adopted to assess pathological changes of lung tissues. Inhibition of Sgk1 dramatically reversed elevated Th9 cells and IL-9 expression in the lung tissues of asthmatic mice. In vitro, Sgk1 promoted Th9 differentiation and elevated p-IKKα, p-IκBα, p-p65, and IRF4 levels, but inhibition of IKKα/IκBα/p65 pathway and IRF4 both reversed enhanced Th9 differentiation by Sgk1. Sgk1→IKKα/IκBα/NF-κBp65→IRF4→Th9 axis may be implicated in asthma development.

Decreased frequency of circulating Th9 cells in patients with chronic hepatitis B infection.

BACKGROUND: Chronic hepatitis B (CHB) is one of the major infectious diseases in which CD4+ T helper (Th) cells play a crucial role. Th9 cells are a distinct subset of CD4+ Th cells with important physiological functions. OBJECTIVE: The study aimed to assess the potential involvement of Th9 cells in the inadequate immune response leading to chronic HBV infection. PATIENTS AND METHODS: Peripheral blood samples were collected from 22 CHB patients and 16 healthy controls (HC). The frequencies of circulating Th9, Tc9, Th1, and Tc1 cells were determined by flow cytometry. Serum levels of IL-9 and IL-10 were analyzed by ELISA. Serum biochemical indices of liver function were measured using an automated analyzers. Serum HBV DNA loads were analyzed by real-time PCR. The potential association of the frequency of Th9, Tc9, Th1 or Tc1 cells with clinical parameters was assessed. RESULTS: The frequency of circulating Th9 cells was significantly lower in CHB patients than those in HC. However, no significant differences in the frequency of Tc9, Th1 or Tc1 cells were observed between the two groups. The percentages of Th9 cells, but not Tc9 cells, were negatively correlated with HBV DNA loads, whereas the percentages of Tc1 cells were positively correlated with viral loads in CHB patients. Moreover, there was a positive correlation between serum levels of IL-9 and IL-10 and HBV DNA loads in patients with chronic HBV infection. CONCLUSION: The depletion of Th9 cells is associated with the development of chronic HBV infection.

Detection of IL-9 producing T cells in the PBMCs of allergic asthmatic patients.

BACKGROUND: Interleukin-9 (IL-9) was reported as an active participant in the pathogenesis of allergic asthma. This study aimed to investigate the major source ofIL-9 and its effect on interferon γ (IFN-γ) and immunoglobulin (Ig) secretion by B cells. METHODS: We isolated peripheral blood mononuclear cells from children with allergic asthma and healthy children. IL-9, IL-4 and IFN-γ expression were detected by ELISA, ELISpot and Flowcytometry. Expression of transcription factor PU.1 was measured by Western Blot. We evaluated the effect of IL-9 on B cell activation and Ig production. RESULTS: Results showed that compared with healthy children, levels of IL-9, IL-4 and PU.1 were elevated and levels of IFN-γ were lower in children with allergic asthma. IL-9-expressing CD4+ T cells did not co-express IL-4. Exogenous IL-9 inhibited IFN-γ production in a dose-dependent manner. Antigen-specific Th9 cells existed in children with house dust mite allergic asthma. IL-9 up-regulated expression of CD69 and CD25 on B cells and combination of IL-9 and IL-4 enhanced IgE production. CONCLUSIONS: In conclusion, our results showed that Th9 cells may be the major source of IL-9 in children with allergic asthma. In these patients, IL-9 impairs IFN-γ production and synergistically promotes IL-4-induced IgE secretion.

Combination of percutaneous thermal ablation and adoptive Th9 cell transfer therapy against non-small cell lung cancer.

BACKGROUND: Non-small cell lung cancer (NSCLC) is one of the predominant malignancies globally. Percutaneous thermal ablation (PTA) has gained widespread use among NSCLC patients, with the potential to elicit immune responses but limited therapeutic efficacies for advanced-stage disease. T-helper type 9 (Th9) cells are a subset of CD4+ effector T cells with robust and persistent anti-tumor effects. This study proposes to develop PTA-Th9 cell integrated therapy as a potential strategy for NSCLC treatment. METHODS: The therapeutic efficacies were measured in mice models with subcutaneously transplanted, recurrence, or lung metastatic tumors. The tumor microenvironments (TMEs) were evaluated by flow cytometry. The cytokine levels were assessed by ELISA. The signaling molecules were determined by quantitative PCR and Western blotting. The translational potential was tested in the humanized NSCLC patient-derived xenograft (PDX) model. RESULTS: We find that PTA combined with adoptive Th9 cell transfer therapy substantially suppresses tumor growth, recurrence, and lung metastasis, ultimately extending the survival of mice with NSCLC grafts, outperforming both PTA and Th9 cell transfer monotherapy. Analysis of TMEs indicates that combinatorial therapy significantly augments tumor-infiltrating Th9 cells, boosts anti-tumor effects of CD8+ T cells, and remodels tumor immunosuppressive microenvironments. Moreover, combinatorial therapy significantly strengthens the regional and circulation immune response of CD8+ T cells in mice with tumor lung metastasis and induces peripheral CD8+ T effector memory cells in mice with tumor recurrence. Mechanically, PTA reinforces the anti-tumor ability of Th9 cells primarily through upregulating interleukin (IL)-1ß and subsequently activating the downstream STAT1/IRF1 pathway, which could be effectively blocked by intercepting IL-1ß signaling. Finally, the enhanced therapeutic effect of combinatorial therapy is validated in humanized NSCLC PDX models. CONCLUSIONS: Collectively, this study demonstrates that combinatorial therapy displays robust and durable anti-tumor efficacy and excellent translational potential, offering excellent prospects for translation and emerging as a promising approach for NSCLC treatment.

IL-9-Producing Th9 Cells Participate in the Occurrence and Development of Iodine-Induced Autoimmune Thyroiditis.

Iodine excess may cause and aggravate autoimmune thyroiditis (AIT), which is regarded as a typical kind of autoimmune disease mainly mediated by CD4+ T cells. Thus far, it is unclear whether T helper (Th) 9 cells, a novel subpopulation of CD4+ T cells, play a potential role in AIT. Therefore, in the present study, changes in Th9 cells were detected in murine models of AIT induced by excess iodine intake to explore the possible immune mechanism. Female C57BL/6 mice were divided into 7 groups (n = 8) and were supplied with water containing 0.005% sodium iodide for 0, 2, 4, 6, 8, 10, and 12 weeks. With the extension of the high-iodine intake duration, the incidence of thyroiditis and the spleen index were significantly increased, and serum thyroglobulin antibody (TgAb) titers and interleukin 9 (IL-9, major cytokine from Th9 cells) concentrations were also increased. Additionally, it was revealed that the percentages of Th9 cells in spleen mononuclear cells (SMCs) and thyroid tissues were both markedly elevated and accompanied by increased mRNA and protein expression of IL-9 and key transcription factors of Th9 cells (PU.1 and IRF-4). Significantly, dynamic changes in Th9 cells were found, with a peak at 8 weeks after high iodine intake, the time point when thyroiditis was the most serious. Importantly, Th9 cells were detected in the areas of infiltrating lymphocytes in thyroid sections. In conclusion, the continuously increasing proportions of Th9 cells may play an important role in the occurrence and development of AIT induced by high iodine intake.

Transcription Factor Id1 Plays an Essential Role in Th9 Cell Differentiation by Inhibiting Tcf3 and Tcf4.

T helper type 9 (Th9) cells play important roles in immune responses by producing interleukin-9 (IL-9). Several transcription factors are responsible for Th9 cell differentiation; however, transcriptional regulation of Th9 cells is not fully understood. Here, it is shown that Id1 is an essential transcriptional regulator of Th9 cell differentiation. Id1 is induced by IL-4 and TGF-ß. Id1-deficient naïve CD4 T cells fail to differentiate into Th9 cells, and overexpression of Id1 induce expression of IL-9. Mass spectrometry analysis reveals that Id1 interacts with Tcf3 and Tcf4 in Th9 cells. In addition, RNA-sequencing, chromatin immunoprecipitation, and transient reporter assay reveal that Tcf3 and Tcf4 bind to the promoter region of the Il9 gene to suppress its expression, and that Id1 inhibits their function, leading to Th9 differentiation. Finally, Id1-deficient Th9 cells ameliorate airway inflammation in an animal model of asthma. Thus, Id1 is a transcription factor that plays an essential role in Th9 cell differentiation by inhibiting Tcf3 and Tcf4.

Enhancement of T cell infiltration via tumor-targeted Th9 cell delivery improves the efficacy of antitumor immunotherapy of solid tumors.

Insufficient infiltration of T cells severely compromises the antitumor efficacy of adoptive cell therapy (ACT) against solid tumors. Here, we present a facile immune cell surface engineering strategy aiming to substantially enhance the anti-tumor efficacy of Th9-mediated ACT by rapidly identifying tumor-specific binding ligands and improving the infiltration of infused cells into solid tumors. Non-genetic decoration of Th9 cells with tumor-targeting peptide screened from phage display not only allowed precise targeted ACT against highly heterogeneous solid tumors but also substantially enhanced infiltration of CD8+ T cells, which led to improved antitumor outcomes. Mechanistically, infusion of Th9 cells modified with tumor-specific binding ligands facilitated the enhanced distribution of tumor-killing cells and remodeled the immunosuppressive microenvironment of solid tumors via IL-9 mediated immunomodulation. Overall, we presented a simple, cost-effective, and cell-friendly strategy to enhance the efficacy of ACT against solid tumors with the potential to complement the current ACT.

Cbx4 governs HIF-1α to involve in Th9 cell differentiation promoting asthma by its SUMO E3 ligase activity.

The potential role of polycomb chromobox 4 (Cbx4), as a small ubiquitin-like ligase (SUMO) E3 ligase, in the development and exacerbation of asthma remains unclear. Hypoxia inducible factor-1 (HIF-1) is a key transcription factor in the cellular response to hypoxia and contributes to the pathogenesis and progression of a range of diseases, including asthma. Here, we aimed to investigate the interaction of Cbx4 with Hypoxia inducible factor-1α (HIF-1α) and the potent mechanism of action in asthma progression. In present study, in vitro and ex vivo results demonstrated that Cbx4 interacts with HIF-1α protein through its SUMO E3 ligase activity and enhances the sumoylation, which increases HIF-1 transactivation through Cbx4 and promotes the differentiation of Th9 cells, then in turn promotes the process of asthma. Treatment of inhibitors targeting SUMO E3 ligase activity of Cbx4 or HIF-1α can effectively reduce HIF-1α activation and differentiation of Th9 cells, which further attenuates the asthma in mouse model. Current results collectively demonstrated Cbx4 can govern HIF-1α to involve in Th9 cell differentiation promoting asthma by its SUMO E3 ligase activity, providing a new direction for clinical treatment of asthma.

Foxp2 inhibits Th9 cell differentiation and attenuates allergic airway inflammation in a mouse model of ovalbumin-induced asthma.

This study aimed to explore the effects of forkhead box P2 gene (Foxp2) on T-helper 9 (Th9) differentiation in asthmatic mice. An in vivo asthmatic mouse model was induced with ovalbumin (OVA). An in vitro model was established by culturing CD4+ T cells with TGF-ß, IL-4, and anti-IFN-γ. ELISA, flow cytometry, qRT-PCR and Western blot were performed to examine IL-9 secretion, Th9 cell number, and Th9 cell transcription factor expression, respectively. Pathological changes in lung tissues and airway mucus secretion were assessed with HE and PAS glycogen staining. Anti-IL-9 mAb reversed the elevation in Th9 cells and IL-9 expression in lung tissues and bronchoalveolar lavage fluid (BALF) of asthmatic mice. Foxp2 was downregulated in BALF and lung tissue of asthmatic mice and Th9 cells. Overexpression of Foxp2 inhibited Th9 cell differentiation in vitro and improved airway inflammation in vivo. Our study suggests that overexpression of Foxp2 attenuates allergic asthma by inhibiting Th9 cell differentiation.

Suppressive effect of dexamethasone on murine Th9 cell-mediated nasal eosinophilic inflammation.

BACKGROUND: Th9 cells have been implicated in the development of allergic inflammation, though its contribution to allergic rhinitis and the effect of steroid on Th9 cell-mediated nasal responses are unclear. OBJECTIVE: In this study, allergen-induced nasal inflammatory responses and their steroid responsiveness were investigated in ovalbumin (OVA)-specific Th9 cell-transferred mice. METHODS: BALB/c mice were transferred with in vitro-differentiated Th9 cells and challenged by intranasal injection of OVA with or without subcutaneous administration of dexamethasone (Dex). Then, the infiltration of inflammatory cells in the nasal mucosa and nasal hyperresponsiveness (NHR) was assessed. RESULTS: The significant NHR accompanied by nasal infiltration of eosinophils as well as allergen-specific T cells was induced in Th9 cell-transferred mice upon allergen challenge. These responses were strongly suppressed by the treatment with Dex. CONCLUSION: The participation of Th9 cells in the pathogenesis of allergic rhinitis was suggested.

miR-143/145 inhibits Th9 cell differentiation by targeting NFATc1.

Th9 cells are a defined CD4+ helper T cell subgroup found to promote or suppress oncogenesis in a context-dependent manner. How microRNAs (miRNAs) shape Th9 cell functionality, however, remains to be studied. Herein, we determined that miR-143/145 is downregulated during Th9 differentiation. When these miRNAs were upregulated, this inhibited Th9 differentiation, proliferation, and IL-9 production. Overexpressing miR-143/145 in Th9 cells further suppressed NFATc1 expression at the protein and mRNA level, whereas the opposite phenotype was observed when miR-143/145 was downregulated in these cells. NFATc1 silencing markedly inhibited Th9 cell differentiation, whereas overexpressing this transcription factor was sufficient to reverse miR-143/145-associated phenotypes in these cells. These findings thus indicate that the ability of miR-143/145 to inhibit Th9 cell differentiation is attributable to their ability to target and suppress NFATc1 expression. Overall, our results highlight a novel mode of action whereby miR-143/145 controls Th9 differentiation, suggesting that this pathway may be amenable to therapeutic targeting in the context of anti-cancer treatment in the future.

Interleukin-35 Promotes Th9 Cell Differentiation in IgG4-Related Disorders: Experimental Data and Review of the Literature.

IgG4-related disease (IgG4-RD) is characterized by intense infiltration of IgG4-positive plasma cells in affected organs. However, the mechanisms acting in the immune responses in IgG4-RD are not fully understood. The aim of this study was to dissect the mechanism underlying the immunoglobulin class switch in IgG4-RD by addressing the crosstalk between IL-35-producing and Th9 cells. The expression level of IL-35 was examined in plasma samples from patients with hepatobiliary and/or pancreatic manifestations of IgG4-RD. Our data demonstrate that IgG4-RD patients exhibit significantly high-level productions of IL-35 as compared to disease and healthy controls. We detected the two subunits of IL-35, EBI3 and IL-12p35, in the two major affected organs, liver and pancreatic tissue, from IgG4-RD. The EBI3- and IL-12p35-positive cells were significantly higher in affected organs in IgG4-RD as compared to disease controls. The colocalization of EBI3 with CD19 and CD38, markers for B cells, suggest the presence of IL-35-producing B cells in affected organs in IgG4-RD. The effects of IL-35 in Th9 differentiation and IL-9 in production of immunoglobulin were then assessed. Surprisingly, IL-35 treatment promoted naïve CD4 T cell differentiating towards Th9 cells through IRF4 signaling. As a consequence, IL-9 secreted by Th9 cells promoted the differentiation of plasma cells and production of IgG1 and IgG4, predominantly IgG4. In conclusion, our data demonstrate that IL-35 actively participates in the process of inflammation and plays an important role in Th9 differentiation resulting in an immunoglobulin class switch towards IgG4.

Th9 cells are subjected to PD-1/PD-L1-mediated inhibition and are capable of promoting CD8 T cell expansion through IL-9R in colorectal cancer.

Th9 cells are named after their expression of IL-9. Studies in recent years demonstrated that Th9 cells could contribute to antitumor immunity by enhancing the recruitment and activation of mast cells, natural killer cells, CD8 T cells, and dendritic cells in the tumor microenvironment. To determine whether Th9 cells participate in colorectal cancer (CRC), we collected resected tumor samples from 20 CRC patients. In the tumor-infiltrating lymphocytes (TILs), IL-9+IL-4- CD4+ T cells could be observed and were present at higher frequencies than the IL-9+IL-4+ and the IL-9-IL-4+ cells, suggesting that the majority of IL-9-producing TILs were bona fide Th9 cells. IL-9-secreting TILs presented particularly high PD-1 expression directly ex vivo. The expression of IL-9 was significantly reduced with PD-L1-mediated inhibition, which in turn was suppressed by anti-PD-1 blocking. Interestingly, the circulating CD4+ T cell compartment in CRC patients also presented Th9 enrichment, characterized by higher IL-9+IL-4- and IL-9+IL-4+ cell frequencies in the CXCR3-CCR6- compartment as compared to that in non-cancer controls. Using exogenous TGF-ß and IL-4, we were capable of enriching Th9 cells without concurrent enrichment of Th2 cells. Th9-enriched CD4+ T cells, but not Th9-non-enriched cells, significantly increased the expansion of activated CD8+ T cells, in a manner that was dependent on the expression of IL-9R. In addition, the frequencies of Th9 cells in the tumor were positively correlated with the frequencies of CD8+ TILs. Together, we demonstrated that Th9 cells infiltrated CRC tumor, could be regulated via the PD-1/PD-L1 pathway, and could contribute the CD8+ T cell expansion.

T Helper 9 Cells: A New Player in Immune-Related Diseases.

The helper T cell 9 (Thelper-9, Th9), as a functional subgroup of CD4+T cells, was first discovered in 2008. Th9 cells expressed transcription factor PU.1 and cytokine interleukin-9 (IL-9) characteristically. Recent researches have shown that the differentiation of Th9 cells was coregulated by cytokine transforming growth factor ß, IL-4, and various transcription factors. Th9 cells, as a new player, played an important role in various immune-related diseases, including tumors, inflammatory diseases, parasite infection, and other diseases. In this article, we summarize the related research progress and discuss the possible prospect.

Emerging Roles of Th9 Cells as an Anti-tumor Helper T Cells.

The newly discovered Th9 cells are the distinct subset of CD4+ T helper (Th) cells, which are involved in various pathophysiological conditions of an immune response. In addition to its role in allergic inflammation and elimination of extracellular pathogens, Th9 cells were found to play a key role in inducing anti-tumor immune response. Precisely, the anti-tumor functions of Th9 cells were found to be superior as compared to Th1 and other Th subsets. Th9 cells eliminate tumors via activating innate and adaptive immune cells, and in particular, generating a profound effector cytotoxic T lymphocyte (CTL) response against neo antigens. In addition, it was proposed that Th9 cells were found to induce effector functions of innate cells like dendritic cells, mast cells and NK cells, which further promote a robust anti-tumor immune response. In this review, we highlight the recent advances in differentiation and functions of Th9 cells in anti-tumor immunity.

Mangiferin suppresses allergic asthma symptoms by decreased Th9 and Th17 responses and increased Treg response.

Mangiferin is the major bioactive ingredient in the leaves of Mangifera indica L., Aqueous extract of such leaves have been traditionally used as an indigenous remedy for respiratory diseases including cough and asthma in Traditional Chinese Medicine. Mangiferin was shown to exert its anti-asthmatic effect by modulating Th1/Th2 cytokines imbalance via STAT6 signaling pathway. However, compelling evidence indicated that subtypes of T helpers and regulatory T cells other than Th1/Th2 were also involved in the pathogenesis of asthma. In current study, we investigated the effects of mangiferin on the differentiation and function of Th9, Th17 and Treg cells in a chicken egg ovalbumin (OVA)-induced asthmatic mouse model. Mangiferin significantly attenuated the symptoms of asthma attacks, reduced the total number of leukocytes, EOS and goblet cells infiltration in lung. Simultaneously, treatment with mangiferin remarkably decreased the proportion of Th9 and Th17 cells; reduced the levels of IL-9, IL-17A; inhibited the expression of PU.1 and RORγt in lung. However, the proportion of Treg cells, the expression of IL-10, TGF-ß1 and Foxp3 were increased by mangiferin. Our data suggest that mangiferin exerted anti-asthmatic effect through decreasing Th9 and Th17 responses and increasing Treg response in OVA-induced asthmatic mouse model.

[Relation between ICOS signaling and Th9 cell polarization in mice infected with Schistosoma japonicum].

OBJECTIVE: To detect the expression level of ICOS on Th9 cells in mice infected with Schistosoma japonicum, and investigate the relation between ICOS signaling and Th9 cell polarization. METHODS: Twenty-five mice with S. japonicum infection were used as models. IL-9+cells in CD4+ T cells and ICOS+ cells in Th9 cells of the mice were detected by flow cytometry 0, 4, 7, 9 weeks and 12 weeks after the infection. RESULTS: Compared with that 0 week after the infection, the proportion of Th9 cells in CD4+ T cells of the mice significantly increased 4, 7, 9, 12 weeks after the infection (all P < 0.05), and the proportion of ICOS+ cells in Th9 cells also markedly improved (P < 0.05). CONCLUSIONS: In S. japonicum infection, the ICOS signaling may have a regulatory effect on Th9 cell polarization.

Zinc supplementation plays a crucial role in T helper 9 differentiation in allogeneic immune reactions and non-activated T cells.

T helper (Th) 9 cells play a critical role in immune-mediated diseases, including allergic airway inflammation, autoimmune diseases, and cancer development. Thus, the promotion or suppression of Th9 cell differentiation, transcriptional control, and function is very important for a healthy immune system. Interestingly, T cell maturation, differentiation and function are highly dependent on the individuals' zinc status. This is especially seen in zinc deficient individuals as in the elderly population often suffering of autoimmunity and increased incidence of infections. In this regard, this study examines the impact of zinc supplementation in pharmacological doses on Th9 differentiation in two in vitro models: 1) in mixed lymphocyte cultures (MLC) displaying allogeneic activated T cells in graft versus host disease, and 2) on non-activated resting T cells in peripheral blood mononuclear cells (PBMC). On the one hand, zinc supplementation significantly diminishes IL-4-induced Th9 differentiation in MLC thereby ameliorating this pro-inflammatory allogeneic immunoreaction. On the other hand, Th9 cells are induced in resting T cells in PBMC hence triggering the immunological defense. Thus, zinc supplementation can be considered as useful additive to dampen unwanted allogeneic immunoreactions. Moreover, the pro-inflammatory immune defense in non-reactive T cells can be strengthened, which is a frequent issue in the elderly population having a weakened immune response against invading pathogens.