Nickel differentially regulates NFAT and NF-κB activation in T cell signaling

An international validation study of the interleukin-2 luciferase leukocyte toxicity test (IL-2 Luc LTT) to evaluate potential immunosuppressive chemicals and its performance after use with the interleukin-2 luciferase assay (IL-2 Luc assay)

We previously reported that the IL-2 Luc LTT can detect immunosuppressive effects of drugs that are attributed to their antimitotic activity. Here, we report an official validation study of the IL-2 Luc LTT. In the Phase I study that evaluated five coded chemicals, the within-laboratory reproducibility of three independent laboratories was 100.0%. In the combined results of the Phase I and II studies that evaluated 20 coded chemicals, the between-laboratory reproducibility was 92.0%. When compared with the reference data based on the previously-reported immunotoxicological information, the predictivity of the combined Phase I and II studies was 76.0% for Lab A and 72.0% for Labs B and C. In contrast, in the study in which the lead laboratory examined 37 non-pharmaceutical chemicals, the predictivity of the IL-2 Luc LTT and the IL-2 Luc assay was 48.6% and 64.9%, respectively, whereas that of the combined assays was 74.3%. It is clear that an integrated approach combining multiple assays is necessary for the development of in vitro immunosuppression testing. These data suggest that the IL-2 Luc LTT alone is not sufficient as a component of the integrated approach, but the combination of the IL-2 Luc assay and IL-2 Luc LTT is promising.

The Antimicrobial Peptide Cathelicidin Exerts Immunomodulatory Effects via Scavenger Receptors

An active form of cathelicidin antimicrobial peptide, LL-37, has immunomodulatory and stimulatory effects, though the specific pathways are not clear. The purpose of this study was to identify the cellular pathways by which LL-37 amplifies the inflammation induced by damage-associated molecular patterns (DAMPs). We performed DNA microarray, reverse transcription polymerase chain reaction, immunoblotting, and proximity ligation assays using cultured keratinocytes treated with LL-37 and/or the DAMP poly(I:C), a synthetic double-stranded RNA. In contrast to the combination of LL-37 and poly(I:C), LL-37 alone induced genes related to biological metabolic processes such as VEGFA and PTGS2 (COX-2). Inhibition of FPR2, a known receptor for cathelicidin, partially suppressed the induction of VEGFA and PTGS2. Importantly, VEGFA and PTGS2 induced by LL-37 alone were diminished by the knockdown of scavenger receptors including SCARB1 (SR-B1), OLR1 (SR-E1), and AGER (SR-J1). Moreover, LL-37 alone, as well as the combination of LL-37 and poly(I:C), showed proximity to the scavenger receptors, indicating that LL-37 acts via scavenger receptors and intermediates between them and poly(I:C). These results showed that the broad function of cathelicidin is generally dependent on scavenger receptors. Therefore, inhibitors of scavenger receptors or non-functional mock cathelicidin peptides may serve as new anti-inflammatory and immunosuppressive agents.

Autophagy involvement in T lymphocyte signalling induced by nickel with quantitative phosphoproteomic analysis

Nickel-induced allergic contact dermatitis (ACD) is a common skin disease. The mechanism by which nickel causes ACD is not clear. There is no treatment for it, only symptomatic therapy. However, due to the lifetime sensitization characteristics, the recurrence rate in patients is high. T lymphocytes play a key role in nickel-induced ACD. Elucidating the potential mechanism underlying nickel-induced T lymphocyte signalling might make it possible to achieve targeted treatment of nickel-induced ACD. In our study, a phosphoproteomic approach based on tandem mass tag (TMT) labelling and LCMS/MS analyses was employed. An animal model of nickel allergy was established. Splenic T lymphocytes were purified for quantitative phosphoproteomic analysis. The numbers of phosphoproteins, phosphopeptides and phosphosites identified in this study were 3072, 7977 and 10,200, respectively. Comprehensive gene ontology (GO) analysis combined with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that nickel can significantly affect the phosphorylation of the mTOR signalling pathway in T lymphocytes. Western blotting analysis was used to detect changes in the expression of autophagy-related proteins (Beclin 1, LC3II, and p62). Nickel allergy changed autophagy-related protein expression (p < 0.05). It has been demonstrated that nickel causes autophagy of T lymphocytes in the spleen. Using autophagy inhibitors to intervene, it was found that Th1 differentiation was inhibited, and the expression of Th1-related inflammatory factors was downregulated. Overall, the identification of relevant signalling pathways yielded new insights into the molecular mechanisms underlying nickel allergy and might help in the discovery and development of mechanism-based drugs.

Evaluation of skin sensitization based on interleukin-2 promoter activation in Jurkat cells

Skin sensitization is an allergic reaction caused by certain chemical substances, and is an important factor to be taken into consideration when evaluating the safety of numerous types of products. Although animal testing has long been used to evaluate skin sensitization, the recent trend to regulate such testing has led to the development and use of alternative methods. Skin sensitization reactions are summarized in the form of an adverse outcome pathway consisting of four key events (KE), including covalent binding to skin proteins (KE1), keratinocyte activation (KE2), and dendritic cell activation (KE3). Equivalent alternative methods have been developed for KE1 to KE3, but no valid alternative has yet been developed for the evaluation of KE4 and T-cell activation. Current alternative methods rely on data from KE1 to KE3 to predict the effect of chemicals on skin sensitization. The addition of KE4 data is expected to improve the accuracy and reproducibility of such predictions. The aim of this study was to establish an assay to evaluate KE4 T-cell activation to supplement data on skin sensitization related to KE4. To evaluate T-cell activation, the Jurkat T-cell line stably expressing luciferase downstream of the pro-inflammatory cytokine interleukin-2 promoter was used. After exposure to known skin sensitizing agents and control substances, luciferase activity measurements revealed that this assay was valid for evaluating skin sensitization. However, two skin sensitizers known to have immunosuppressive effects on T-cells reacted negatively in this assay. The results revealed that this assay simultaneously allows for monitoring of the skin sensitization and immuno-suppressiveness of chemical substances and supplements KE4 T-cell activation data, and may thus contribute to reducing the use of animal experiments.

Optimization of the IL-2 Luc assay for immunosuppressive drugs: a novel in vitro immunotoxicity test with high sensitivity and predictivity

We have reported that the IL-2 Luc assay can detect the effects of chemicals on IL-2 promoter activity by using a dual reporter cell line, 2H4 cells that measure IL-2 promoter-driven luciferase activity (IL2LA) and GAPDH promoter-driven luciferase activity (GAPLA). Since the IL-2 Luc assay cannot detect immunosuppressive drugs that are antimitotic towards rapidly proliferating cells, we attempted to establish a new assay to detect these chemicals by taking advantage of the dual reporter cell properties of 2H4 cells. We first determined the optimal incubation time with drugs and the seeding cell density, and confirmed that the change in GAPLA and IL2LA levels reflects the change in cell count and IL-2 production of 2H4 cells after drug treatment. We designed the IL-2 luciferase lymphotoxicity test (IL-2 Luc LTT) to detect the antimitotic effects of chemicals by modifying the protocol and criteria of the IL-2 Luc assay. To determine the performance of the IL-2 Luc LTT and that of the combination of the IL-2 Luc LTT and the IL-2 Luc assay, we examined 46 drugs: 19 immunosuppressive drugs with different mechanisms of action, 12 anti-cancer drugs, and 15 non-immunosuppressive drugs. The performances of the IL-2 Luc LTT, the IL-2 Luc assay and their combination were 43.3%, 61.3%, and 93.3%, respectively, for sensitivity, 84.6%, 53.3%, and 50.0%, respectively, for specificity, and 55.8%, 58.7%, and 79.5%, respectively, for accuracy. These results demonstrated that the combination of these two assays is promising for the detection of immunosuppressive drugs with different mechanisms of action.

MicroRNA expression in lung tissues of asbestos-exposed mice: Upregulation of miR-21 and downregulation of tumor suppressor genes Pdcd4 and Reck

OBJECTIVES

Asbestos causes lung cancer and malignant mesothelioma in humans, but the precise mechanism has not been well understood. MicroRNA (miRNA) is a short non-coding RNA that suppresses gene expression and participates in human diseases including cancer. In this study, we examined the expression levels of miRNA and potential target genes in lung tissues of asbestos-exposed mice by microarray analysis.

METHODS

We intratracheally administered asbestos (chrysotile and crocidolite, 0.05 or 0.2 mg/instillation) to 6-week-old ICR male mice four times weekly. We extracted total RNA from lung tissues and performed microarray analysis for miRNA and gene expression. We also carried out real-time polymerase chain reaction (PCR), Western blotting, and immunohistochemistry to confirm the results of microarray analysis.

RESULTS

Microarray analysis revealed that the expression levels of 14 miRNAs were significantly changed by chrysotile and/or crocidolite (>2-fold, P < .05). Especially, miR-21, an oncogenic miRNA, was significantly upregulated by both chrysotile and crocidolite. In database analysis, miR-21 was predicted to target tumor suppressor genes programmed cell death 4 (Pdcd4) and reversion-inducing-cysteine-rich protein with kazal motifs (Reck). Although real-time PCR showed that Pdcd4 was not significantly downregulated by asbestos exposure, Western blotting and immunohistochemistry revealed that PDCD4 expression was reduced especially by chrysotile. Reck was significantly downregulated by chrysotile in real-time PCR and immunohistochemistry.

CONCLUSIONS

This is the first study demonstrating that miR-21 was upregulated and corresponding tumor suppressor genes were downregulated in lung tissues of asbestos-exposed animals. These molecular events are considered to be an early response to asbestos exposure and may contribute to pulmonary toxicity and carcinogenesis.

Migratory dendritic cells in skin-draining lymph nodes have nickel-binding capabilities

Nickel (Ni) is the most frequent metal allergen and induces Th1-dependent type-IV allergies. In local skin, epidermal Langerhans cells (LCs) and/or dermal dendritic cells (DCs) uptake antigens and migrate to draining lymph nodes (LNs). However, the subsets of antigen-presenting cells that contribute to Ni presentation have not yet been identified. In this study, we analyzed the Ni-binding capabilities of murine DCs using fluorescent metal indicator Newport Green. Elicitation of Ni allergy was assessed after intradermal (i.d.) injection of Ni-treated DCs into ear pinnae of Ni-sensitized mice. The Ni-binding capabilities of MHC class II^hi CD11c^int migratory DCs were significantly stronger than those of MHC class II^int CD11c^hi resident DCs and CD11c^int PDCA1⁺ MHC class II^int B220⁺ plasmacytoid DCs. Migratory DCs in skin-draining and mandibular LNs showed significantly stronger Ni-binding capabilities than those in mesenteric and medial iliac LNs. An i.d. injection of IL-1β induced the activation of LCs and dermal DCs with strong Ni-binding capabilities. Ni-binding LCs were detected in draining LNs after i.d. challenge with IL-1β and Ni. Moreover, an i.d. injection of Ni-treated DCs purified from skin-draining LNs elicited Ni-allergic inflammation. These results demonstrated that migratory DCs in skin-draining LNs have strong Ni-binding capabilities and elicit Ni allergy.

An international validation study of the IL-2 Luc assay for evaluating the potential immunotoxic effects of chemicals on T cells and a proposal for reference data for immunotoxic chemicals

To evaluate the immunotoxic effects of xenobiotics, we have established the Multi-ImmunoTox assay, in which three stable reporter cell lines are used to evaluate the effects of chemicals on the IL-2, IFN-γ, IL-1β and IL-8 promoters. Here, we report the official validation study of the IL-2 luciferase assay (IL-2 Luc assay). In the Phase I study that evaluated five coded chemicals in three sets of experiments, the average within-laboratory reproducibility was 86.7%. In the Phase II study, 20 coded chemicals were evaluated at multiple laboratories. In the combined results of the Phase I and II studies, the between-laboratory reproducibility was 80.0%. These results suggested that the IL-2 Luc assay was reproducible both between and within laboratories. To determine the predictivity, we collected immunotoxicological information and constructed the reference data by classifying the chemical into immunotoxic compounds targeting T cells or others according to previously reported criteria. When compared with the reference data, the average predictivity of the Phase I and II studies was 75.0%, while that of additional 60 chemicals examined by the lead laboratory was 82.5%. Although the IL-2 Luc assay alone is not sufficient to predict immunotoxicity, it will be a useful tool when combined with other immune tests.

Profiling the immunotoxicity of chemicals based on in vitro evaluation by a combination of the Multi-ImmunoTox assay and the IL-8 Luc assay

We established a luciferase reporter assay system, the Multi-ImmunoTox Assay (MITA), which can evaluate the effects of chemicals on the promoter activities of four cytokines: IL-2, IFN-γ, IL-1β, and IL-8. We previously reported that MITA correctly reflected the change in mRNA of human whole-blood cells treated with dexamethasone, cyclosporine, FK506, or several other immunosuppressive drugs. In this study, we combined MITA with the IL-8 Luc assay to detect skin sensitization chemicals (OECD 442E) (modified MITA: mMITA) and established a data set of 60 chemicals examined by mMITA. Using the mMITA results, chemicals can be classified based on the lowest observed effect level (LOEL) of chemicals in suppressing or augmenting the promoter activities of the four cytokines. Moreover, we demonstrated that K-means clustering and hierarchical clustering of the 60 chemicals based on the LOEL for their effects on IL-2 and IL-8 promoter activities and the judgment by the IL-8 Luc assay resulted in the same 6-cluster solution: cluster 1 with preferential suppression of IL-8, cluster 2 with suppression of IL-2 and a positive IL-8 Luc assay result, cluster 3 with suppression of both IL-2 and IL-8, cluster 4 with no effects on IL-2 or IL-8 and a negative IL-8 Luc assay result, cluster 5 with suppression of both IL-2 and IL-8 and a negative IL-8 Luc assay result, and cluster 6 with preferential suppression of IL-8. These data suggest that mMITA is a promising novel high-throughput approach for detecting unrecognized immunological effects of chemicals and for profiling their immunotoxic effects.

Nickel chloride (NiCl2)-caused inflammatory responses via activation of NF-κB pathway and reduction of anti-inflammatory mediator expression in the kidney

Nickel (Ni) or Ni compounds target a number of organs and produce multiple toxic effects. Kidney is the major organ for Ni accumulation and excretion. There are no investigations on the Ni- or Ni compounds-induced renal inflammatory responses in human beings and animals at present. Therefore, we determined NiCl₂-caused alteration of inflammatory mediators, and functional damage in the broiler's kidney by the methods of biochemistry, immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). Dietary NiCl₂ in excess of 300 mg/kg caused the renal inflammatory responses that characterized by increasing mRNA expression levels of the pro-inflammatory mediators including tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8) and interleukin-18 (IL-18) via the activation of nucleic factor κB (NF-κB), and decreasing mRNA expression levels of the anti-inflammatory mediators including interleukin-2 (IL-2), interleukin-4 (IL-4) and interleukin-13 (IL-13). Concurrently, NiCl₂ caused degeneration, necrosis and apoptosis of the tubular cells, which was consistent with the alteration of renal function parameters including elevated alkaline phosphatase (AKP) activity, and reduced activities of sodium-potassium adenosine triphosphatase (Na⁺/K⁺-ATPase), calcium adenosine triphosphatase (Ca²⁺-ATPase), lactic dehydrogenase (LDH), succinate dehydrogenase (SDH) and acid phosphatase (ACP) in the kidney. The above-mentioned results present that the activation of NF-κB pathway and reduction of anti-inflammatory mediator expression are main mechanisms of NiCl2-caused renal inflammatory responses and that the renal function is decreased or impaired after NiCl2-treated.

Oxidative stress and inflammatory responses involved in dietary nickel chloride (NiCl2)-induced pulmonary toxicity in broiler chickens

The respiratory system is the primary target of nickel or nickel compound toxicity after inhalation exposure. There are no reports on the effects of nickel or nickel compounds on the lung via dietary administration at present. This study aimed to investigate pulmonary toxicity induced by dietary NiCl₂ in broiler chickens by using histopathology, qRT-PCR, and ELISA. In comparison with the control group, NiCl₂ intake induced oxidative damage to DNA (upregulation of 8-OHdG) and lipid peroxidation (upregulation of MDA), which was associated with the upregulation of NO and the downregulation of the expression levels and activities of pulmonary CuZn-SOD, Mn-SOD, CAT, GSH-Px, GR and GST mRNA. Also, the T-AOC activity, GSH content, ability to inhibit the generation of hydroxyl radicals, and ratio of GSH/GSSG were decreased in the groups treated with NiCl₂. Concurrently, the mRNA expression levels of iNOS, TNF-α, COX-2, IL-1β, IL-6, IL-8, IL-18 and IFN-γ were increased via the activation of NF-κB, and the mRNA expression levels of anti-inflammatory mediators including IL-2, IL-4 and IL-13 were decreased in the groups treated with NiCl₂. The above-mentioned results were the first to demonstrate that NiCl₂ intake induced pulmonary oxidative stress and inflammatory responses via the dietary pathway, which subsequently contributed to histopathological lesions and dysfunction.

The possible interaction between periostin expressed by cancer stroma and tumor-associated macrophages in developing mycosis fungoides

Mycosis fungoides (MF) starts as an indolent disease, progresses from a patch stage to confluent plaques and ultimately develops skin tumors. Tumor-associated macrophages (TAMs) play roles in maintaining the tumor microenvironment in MF. The purpose of this study was to elucidate the involvement of TAMs in the lesional skin of different stages of MF. First, we immunohistologically examined the percentage of CD163+ macrophages and CD206+ cells, as well as the levels of periostin and IL-4 in cancer stroma. The percentage of CD206+ cells increased in parallel with tumor progression, while there was no significant difference in the percentage of CD163+ cells. Periostin was prominent in the stromal area at the patch and plaque stages but decreased at the tumor stage. In contrast, IL-4 was prominently stained at both plaque and tumor stages. To further elucidate the molecular mechanisms of the effects of these stromal factors on TAMs, we examined their effects on mRNA expression in monocyte-derived macrophages in vitro. Based on microarray analysis and gene ontology, we examined a series of chemokines and MMPs whose expression was strongly connected with periostin stimulation. The DNA microarray results were verified in M2 macrophages using real-time PCR. We further examined the mRNA expression of these chemokines and MMPs in the presence of periostin and IL-4 to simulate the advanced stages of MF and validated their protein expression by ELISA. Our present report suggests possible roles of periostin on TAMs in establishing the tumor microenvironment in MF.

Optimization of the IL-8 Luc assay as an in vitro test for skin sensitization

We previously reported a dataset of the IL-8 Luc assay covering reference chemicals published by ECVAM, in which the effects of chemicals on IL-8 promoter activity were evaluated by an IL-8 reporter cell line, THP-G8 cells. To clarify its performance, we created another dataset of 88 sensitizers and 34 non-sensitizers. Simultaneously, to improve its performance, we changed the incubation time from 5 h to 16 h, deleted the criterion regarding the effects of N-acetylcysteine, and set an exclusion criterion for detergents. These modifications significantly improved its performance. In addition, we examined the following three criteria to judge chemicals as sensitizers: Criterion 1: Fold induction of SLO luciferase activity (FlnSLO-LA)⩾1.4, Criterion 2: the lower limit of the 95% confidence interval of FInSLO-LA⩾1.0, Criterion 3: the intersection of criteria 1 and 2. Among them, Criterion 1 produced the best performance, demonstrating that the accuracy, sensitivity and specificity were 81%, 79%, and 90%, respectively. In addition, we found that the IL-8 Luc assay solubilizing chemicals with X-VIVO substantially improved its performance. Finally, the IL-8 Luc assay combined with DPRA and DEREK could improve substantially its performance. These data suggest that the IL-8 Luc assay is a promising test method to screen skin sensitizers.

Dual-color bioluminescence imaging assay using green- and red-emitting beetle luciferases at subcellular resolution

Bioluminescence imaging is widely used to monitor cellular events, including gene expression in vivo and in vitro. Moreover, recent advances in luciferase technology have made possible imaging at the single-cell level. To improve the bioluminescence imaging system, we have developed a dual-color imaging system in which the green-emitting luciferase from a Brazilian click beetle (Emerald Luc, ELuc) and the red-emitting luciferase from a railroad worm (Stable Luciferase Red, SLR) were used as reporters, which were localized to the peroxisome and the nucleus, respectively. We clearly captured simultaneously the subcellular localization of ELuc in the peroxisome and SLR in the nucleus of a single cell using a high-magnification objective lens with 3-min exposure time without binning using a combination of optical filters. Furthermore, to apply this system to quantitative time-lapse imaging, the activation of nuclear factor triggered by tumor necrosis factor α was measured using nuclear-targeted SLR and peroxisome-targeted ELuc as the test and internal control reporters, respectively. We successfully quantified the kinetics of activation of nuclear factor κB using nuclear-targeted SLR and the transcriptional change of the internal control promoter using peroxisome-targeted ELuc simultaneously in a single cell, and showed that the activation kinetics, including activation rate and amplitude, differed among cells. The results demonstrated that this imaging system can visualize the subcellular localization of reporters and track the expressions of two genes simultaneously at subcellular resolution.

Possible implications of Ni(II) on oral IL-1β-induced inflammatory processes

OBJECTIVES

Nickel (Ni) is one of the main metal elements in orthodontic and prosthetic devices. Different effects of Ni are described ranging from an induction of local inflammation to allergy and cancerous/mutagenic properties. Inflammatory reactions are frequently observed in the oral cavity, but the interrelationship of Ni with those events is still unknown. Therefore, we focused on the impact of Ni on inflammation in vitro.

METHODS

In accordance to previous immersion tests of our lab, human gingival fibroblasts (HGFs) (n=6) were exposed to a pro-inflammatory environment using interleukin-1 beta (IL-1β) and additionally stimulated with different Ni(II) concentrations (400 and 4000ng/ml). At varying time points the expression of pro- and anti-inflammatory as well as matrix degeneration proteins, i.e. MMPs, were analyzed. Furthermore, proliferation assays, wound healing tests and the detection of NF-κB activation were conducted. Unstimulated HGFs served as control.

RESULTS

Our experiments showed that low clinical average Ni(II) levels did not alter pro-inflammatory cytokines significantly compared to control (p>0.05). Instead, a 10-fold higher dose up-regulated these mediators significantly in a time-dependent manner (p<0.01). This was even more pronounced combining both Ni(II) concentrations with an inflammatory condition (p<0.001), MMP expressions were in line with our findings (p<0.001). The mRNA data were supported by proliferation and wound closure assays (p<0.001). However, the combination of both stimuli induced contradictory results. Analyzing NF-κB activation revealed that our results may be in part attributed to NF-κB.

SIGNIFICANCE

Our in vitro study implicated that Ni(II) has various modifying effects on IL-1β-induced inflammatory processes depending on the concentration.

Alarmin function of cathelicidin antimicrobial peptide LL37 through IL-36γ induction in human epidermal keratinocytes

Several dermatoses, including psoriasis, atopic dermatitis, and rosacea, alter the expression of the innate immune effector human cathelicidin antimicrobial peptide (CAMP). To elucidate the roles of aberrant CAMP in dermatoses, we performed cDNA array analysis in CAMP-stimulated human epidermal keratinocytes, the primary cells responding to innate immune stimuli and a major source of CAMP LL37 in skin. Among LL37-inducible genes, IL-1 cluster genes, particularly IL36G, are of interest because we observed coordinate increases in CAMP and IL-36γ in the lesional skin of psoriasis, whereas virtually no CAMP or IL-36γ was observed in nonlesional skin and normal skin. The production and release of IL-36γ were up to 20-30 ng/ml in differentiated keratinocytes cultured in high-calcium media. G-protein inhibitor pertussis toxin and p38 inhibitor suppressed IL-36γ induction by LL37. As an alarmin, LL37 induces chemokines, including CXCL1, CXCL8/IL8, CXCL10/IP-10, and CCL20/MIP3a, and IL-36 (10-100 ng/ml) augments the production of these chemokines by LL37. Pretreatment with small interfering RNA against IL36γ and IL-36R IL36R/IL1RL2 and IL1RAP suppressed LL37-dependent IL8, CXCL1, CXCL10/IP10, and CCL20 production in keratinocytes, suggesting that the alarmin function of LL37 was partially dependent on IL-36γ and its receptors. Counting on CAMP induction in innate stimuli, such as in infection and wounding, IL-36γ induction by cathelicidin would explain the mechanism of initiation of skin inflammation and occasional exacerbations of psoriasis and skin diseases by general infection.

Evaluation of the Multi-ImmunoTox Assay composed of 3 human cytokine reporter cells by examining immunological effects of drugs

We established a luciferase reporter assay system, the Multi-ImmunoTox Assay (MITA), to evaluate the effects on key predictivein vitro components of the human immune system. The system is composed of 3 stable reporter cell lines transfected with 3 luciferase genes, SLG, SLO, and SLR, under the control of 4 cytokine promoters, IL-2, IFN-γ, IL-1β, and IL-8, and the G3PDH promoter. We first compared the effects of dexamethasone, cyclosporine, and tacrolimus on these cell lines stimulated with phorbol 12-myristate 13-acetate and ionomycin, or lipopolysaccharides, with those on mRNA expression by the mother cell lines and human whole blood cells after stimulation. The results demonstrated that MITA correctly reflected the change of mRNA of the mother cell lines and whole blood cells. Next, we evaluated other immunosuppressive drugs, off-label immunosuppressive drugs, and non-immunomodulatory drugs. Although MITA did not detect immunosuppressive effects of either alkylating agents or antimetabolites, it could demonstrate those of the off-label immunosuppressive drugs, sulfasalazine, chloroquine, minocycline, and nicotinamide. Compared with the published immunological effects of the drugs, these data suggest that MITA can present a novel high-throughput approach to detect immunological effects of chemicals other than those that induce immunosuppressive effects through their inhibitory action on cell division.