Prostaglandin E2 and IL-4 provide naive CD4+ T cells with distinct inhibitory signals for the priming of IFN-gamma production

Allergen uptake, activation, and IL-23 production by pulmonary myeloid DCs drives airway hyperresponsiveness in asthma-susceptible mice

Maladaptive, Th2-polarized inflammatory responses are integral to the pathogenesis of allergic asthma. As regulators of T cell activation, dendritic cells (DCs) are important mediators of allergic asthma, yet the precise signals which render endogenous DCs “pro-asthmatic”, and the extent to which these signals are regulated by the pulmonary environment and host genetics, remains unclear. Comparative phenotypic and functional analysis of pulmonary DC populations in mice susceptible (A/J), or resistant (C3H) to experimental asthma, revealed that susceptibility to airway hyperresponsiveness is associated with preferential myeloid DC (mDC) allergen uptake, and production of Th17-skewing cytokines (IL-6, IL-23), whereas resistance is associated with increased allergen uptake by plasmacytoid DCs. Surprisingly, adoptive transfer of syngeneic HDM-pulsed bone marrow derived mDCs (BMDCs) to the lungs of C3H mice markedly enhanced lung IL-17A production, and rendered them susceptible to allergen-driven airway hyperresponsiveness. Characterization of these BMDCs revealed levels of antigen uptake, and Th17 promoting cytokine production similar to that observed in pulmonary mDCs from susceptible A/J mice. Collectively these data demonstrate that the lung environment present in asthma-resistant mice promotes robust pDC allergen uptake, activation, and limits Th17-skewing cytokine production responsible for driving pathologic T cell responses central to the development of allergen-induced airway hyperresponsiveness.

Facilitation of Th1-mediated immune response by prostaglandin E receptor EP1

Prostaglandin E₂ (PGE₂) exerts its actions via four subtypes of the PGE receptor, EP1–4. We show that mice deficient in EP1 exhibited significantly attenuated Th1 response in contact hypersensitivity induced by dinitrofluorobenzene (DNFB). This phenotype was recapitulated in wild-type mice by administration of an EP1-selective antagonist during the sensitization phase, and by adoptive transfer of T cells from sensitized EP1^−/− mice. Conversely, an EP1-selective agonist facilitated Th1 differentiation of naive T cells in vitro. Finally, CD11c⁺ cells containing the inducible form of PGE synthase increased in number in the draining lymph nodes after DNFB application. These results suggest that PGE₂ produced by dendritic cells in the lymph nodes acts on EP1 in naive T cells to promote Th1 differentiation.

Cyclooxygenase-2 inhibition promotes enhancement of antitumor responses by transcutaneous vaccination with cytosine-phosphate-guanosine-oligodeoxynucleotides and model tumor antigen

One of the principal goals in tumor immune prophylaxis and tumor therapy is the induction of antitumor responses by generating sufficient numbers of tumor antigen-specific helper T (Th)1 cells and cytotoxic T lymphocytes (CTLs). We have demonstrated that the administration of cytosine-phosphate-guanosine-oligodeoxynucleotide (CpG-ODN) through tape-stripped skin induced a Th1-type immune response and suggested that the skin is a potential site for vaccination. CpG-ODN induces the expression of cyclooxygenase (COX)-2, and its product prostaglandin (PG) E2 underlies an immunosuppressive network, therefore it is a simple strategy to use a COX-2 inhibitor for tumor vaccination with CpG-ODN. In this study, we examined whether a COX-2 inhibitor enhances the antitumor immune response induced by CpG-ODN with model tumor antigen, ovalbumin (OVA), applied to tape-stripped skin in mice. The COX-2 inhibitor remarkably enhanced antigen-specific Th1-type immune responses and generation of CTLs induced by transcutaneous vaccination with CpG-ODN and OVA. PGE2 and IL-10 levels in the skin were significantly decreased and production of IL-12 was enhanced. This vaccination also induces an effective antitumor immunity in tumor-challenged mice. These results suggested that transcutaneous vaccination with a COX-2 inhibitor, CpG-ODN, and tumor antigen is a very simple and cost-effective strategy for tumor vaccine and may be readily achievable.

Murine serum cytokines throughout the estrous cycle, pregnancy and post partum period

Cytokines are pleiotropic glycoproteins participating in many aspects of mammalian reproductive physiology. Although murine models have been established to study normal and pathological pregnancy, the small volume of retrievable sample has hampered investigations into the role of cytokines in these processes. These problems were overcome by using fluid-phase multiplex immunoassays to monitor the serum profiles of 18 cytokines in single animals throughout normal murine reproduction: estrus, diestrus, post coitum, preimplantation, implantation, mid-pregnancy, late pregnancy and post partum. Most cytokines were detectable throughout all stages studied. Modest changes in profile were associated with estrous cyclicity and early pregnancy while virtually all cytokine levels increased markedly in mid- to late pregnancy and either fell slightly or levelled off post partum. The functional interrelationships between the various cytokines and the hormonal milieu are discussed with respect to gestational stage. Although certain profiles supported the 'conventional' Th1:Th2 cytokine paradigm of pregnancy, many of the changes recorded were orchestrated around IL-12 (p40) and (p70). The present findings suggest that the traditional cytokine dichotomy poorly describes complex immunological processes like pregnancy.

Prostaglandin E2-mediated regulation of immunoglobulin G2 via interferon gamma

BACKGROUND

Patients with localized aggressive periodontitis (LAgP) produce elevated levels of IgG2 both in vivo and in vitro. Responses to the periodontitis-associated pathogens Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis are dominated by IgG2, and these IgG2 responses are associated with reduced extent and severity of disease. Little is known about regulation of the IgG2 subclass, although prostaglandin E2 (PGE2) (a mediator known to polarize responses toward Th-2) and interferon (IFN)-gamma (a Th-1 mediator) both promote IgG2 production. This unusual relationship prompted the hypothesis that, in certain circumstances, PGE2 enhances rather than inhibits IFN-gamma production.

METHODS

To test this hypothesis, indomethacin (IND)-treated peripheral blood mononuclear cell (PBL) cultures from healthy volunteers were stimulated with pokeweed mitogen (PWM), and the cultures were manipulated by adding PGE2, rIFN-gamma, rIL-Ialpha, rIL-1beta, rIL-6, or rIL-12. Production of IgG1, IgG2, IFN-gamma, and PGE2 was monitored by enzyme-linked immunosorbent assay.

RESULTS

Indomethacin treatment inhibited IgG1 and IgG2 production, and PGE2 restored both immunoglobulins in PWM-stimulated cultures. Remarkably, addition of IFN-gamma also restored IND-suppressed IgG2 but not IgG1. In contrast, addition of rIL (interleukin)-1alpha, rIL-1beta, rIL-6, or rIL-12 did not restore IgG2 responses. Furthermore, IND suppressed IFN-gamma production and PGE2 increased IFN-gamma levels. Kinetic studies indicate that PGE2 production occurred on the first day of culture, followed by IFN-gamma two days later.

CONCLUSIONS

These findings support the concept that in certain circumstances, PGE2 production can lead to increased IFN-gamma and that this IFN-gamma selectively promotes IgG2 responses. These data suggest that the elevated PGE2 observed in LAgP patients may contribute to increased IFN-gamma production and help explain elevated IgG2 responses.

Macrophages and post-burn immune dysfunction

The activation of a pro-inflammatory cascade after burn injury appears to be important in the development of subsequent immune dysfunction, susceptibility to sepsis and multiple organ failure. Macrophages are major producers of pro-inflammatory mediators and their productive capacity for these mediators is markedly enhanced following thermal injury. Thus, macrophage hyperactivity (as defined by increased productive capacity for pro-inflammatory mediators) appears to be of critical importance in the development of post-burn immune dysfunction. This review will focus on the current state of knowledge with regards to the role of macrophages in the development of post-burn immune dysfunction. Particular areas of discussion include: nitric oxide synthase (NOS) and cyclooxygenase (COX) enzyme systems, macrophages and the T-helper (Th)-1/Th-2 cytokine responses, alterations in macrophages signal transduction and a potential role for gamma/delta T-cells in the development of macrophage hyperactivity following thermal injury. A more comprehensive understanding of the relationship between macrophage activity and post-burn immune dysfunction will hopefully provide the basis for improved therapeutic regimes in the treatment of burn patients.

Expression of intracellular Th1 and Th2 cytokines in women with recurrent spontaneous abortion, implantation failures after IVF/ET or normal pregnancy

PROBLEM

We aimed to investigate absolute counts of intracellular T helper 1 (Th1) and Th2 cytokine expressing T-cell subpopulations in women with three or more recurrent spontaneous abortions (RSA), multiple implantation failures after in-vitro fertilization and embryo transfer (IVF/ET) (three or more) or during normal pregnancy.

METHOD OF STUDY

Absolute cell counts and percentages of CD3+, CD3+/CD4+, and CD3+/CD8+ T-cell populations expressing intracellular cytokines [interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-4 and IL-10] was studied by four-color flow cytometry in 15 RSA and 13 implantation failure patients. Eighteen fertile non-pregnant and 47 normal pregnant women were also compared with regard to intracellular cytokine expression.

RESULTS

Interleukin-10 producing CD3+/CD8+ T-cell counts were significantly lower in women with RSA (P < 0.05) and implantation failures (P < 0.05), and TNF-alpha producing CD3+/CD4+ T-cell counts were higher in women with RSA (P < 0.05) and implantation failures (P < 0.005) than those of non-pregnant fertile controls. During normal pregnancies, first trimester IL-4 expressing CD3+, CD3+/CD4+ T-cell counts (P < 0.05) and IFN-gamma expressing CD3+ T-cell counts (P < 0.05) were significantly higher than those of third trimester (P < 0.05). First trimester TNF-alpha expressing CD3+/CD8+ T-cell counts were significantly higher than those of second and third trimester women (P < 0.05). However, there are no differences in cytokine expression between non-pregnant and first trimester pregnant women.

CONCLUSION

Absolute counts of IFN-gamma, IL-4, and TNF-alpha expressing T cells decrease with the progress of gestation (third trimester) during normal pregnancies. In women with implantation failures, absolute cell counts of TNF-alpha expressing CD3+/ 4- cells reflects the presence of dominant Th1 immune response. A significantly increased Th1 cytokine expression may be the underlying immune etiology for reproductive failures.

Phospholipase A(2) and cyclooxygenase gene expression in human preimplantation embryos

Phospholipase A(2) (PLA(2)) and cyclooxygenase (COX) are two key enzymes in PG synthesis; the latter has two forms, COX-1 and COX-2. mRNA was extracted from single preimplantation embryos and examined for PLA(2), COX-1, and COX-2 gene expression by RT-PCR to investigate whether PLA(2) and COX genes are expressed in human preimplantation conceptuses from zygote to blastocyst stage and to compare COX-1 and COX-2 gene expression within the same stage of embryonic development. Expression of PLA(2), COX-1, and COX-2 was detected in 48, 37, and 45%, respectively, of total embryos examined. COX-1 was expressed in approximately 66% of early human preimplantation embryos from zygote to two-cell stage, whereas COX-2 was expressed in about 58% of later stage embryos from eight-cell to blastocyst stage (P < 0.05). Furthermore, COX-2 mRNA and protein were localized to trophectoderm in blastocyst stage embryos. In conclusion, PLA(2), COX-1, and COX-2 are expressed during early human embryonic development and may contribute to the production of PGs such as PGE(2) in human embryogenesis. COX-1 and COX-2 are differentially expressed, with COX-2 being primarily expressed by trophectoderm in late-stage human preimplantation embryos, which may promote embryonic differentiation and implantation.

Cyclooxygenase 2-mediated suppression of macrophage interleukin-12 production after thermal injury

Macrophage (Mphi) prostaglandin (PG)E(2) production has been implicated in immunosuppression and increased susceptibility to sepsis after thermal injury. Deficient interleukin (IL)-12 production has also been implicated in these postburn complications. The present study examined the relationship between Mphi cyclooxygenase (COX)-2 activity and IL-12 production after thermal injury. C57BL/6 female mice were subjected to a 25% total body surface area full-thickness burn. Mphi were isolated 7 days later, or the mice were subjected to sepsis by cecal ligation and puncture (CLP). IL-12 production by Mphi from injured mice was suppressed by >50%, whereas COX-2 expression and PGE(2) production were increased twofold. The COX-2 inhibitor NS-398 suppressed PGE(2) production and normalized IL-12 production in the injury group, whereas it had no effect on IL-10 production. Injured mice subjected to CLP had lower IL-12 plasma levels compared with sham-treated mice subjected to CLP. NS-398 treatment prevented the suppression in plasma IL-12 levels in the injury group. Thus elevated Mphi COX-2 activity, independent of IL-10, suppresses Mphi IL-12 production after thermal injury and may play an important role in the observed immunosuppression under such conditions.

Suppression of allergic reactions by royal jelly in association with the restoration of macrophage function and the improvement of Th1/Th2 cell responses

We studied the immunomodulatory effects of royal jelly (RJ), the principal food source of the queen honeybee. In this study, suppression of allergic reactions by RJ was investigated in DNP-KLH immunized mice (DNP-KLH mice). Oral administration of RJ (1 g/kg) to DNP-KLH mice significantly decreased the serum levels of antigen-specific Ig E and significantly inhibited DNP-KLH mediated-histamine release from mast cells, resulting in the suppression of immediate hypersensitivity reactions of ear skin. In DNP-KLH mice, IFN-gamma (Th1 cytokine) production from CD4+ T cells was suppressed and IL-4 (Th2 cytokine) production from CD4+ T cells was increased as compared to normal mice. On the other hand, RJ improved the balance of Th1/Th2 cell responses from Th2-dominant to Th1-dominant. RJ significantly increased GSH levels in macrophages from DNP-KLH mice. In addition, the administration of RJ to DNP-KLH mice increased IL-12 p40 mRNA expression and NO production, and decreased PG E2 production from macrophages as compared to untreated DNP-KLH mice. These results suggested that RJ suppressed antigen-specific Ig E production and histamine release from mast cells in association with the restoration of macrophage function and improvement of Th1/Th2 cell responses in DNP-KLH mice.

Prostaglandin E2 up-regulates macrophage-derived chemokine production but suppresses IFN-inducible protein-10 production by APC

PGE(2) has been known to suppress Th1 responses. We studied the role of PGE(2) in two representative chemokines, macrophage-derived chemokine (MDC) and IFN-inducible protein-10, production by LPS- or CD40-stimulated spleen cells. The production of MDC, one of the ligands for CCR4 preferentially expressed on Th2, was enhanced in nonstimulated, LPS-, CD40-, or CD3-stimulated spleen cells by the pretreatment with PGE(2), while the production of IFN-inducible protein-10, a representative ligand for CXC chemokine receptor 3 expressed on Th1, was suppressed. MDC production was also enhanced by IL-4, IL-5, and intracellular cAMP-elevating agents such as dibutyryl cAMP and 3-isobutyl-1-methylxanthine, and the effect of IL-4, IL-5, and PGE(2) was additive. However, the pretreatment with IL-6, IL-10, or TGF-beta, or the neutralization of IFN-gamma or IL-12 had no effect on MDC production. B cells, macrophages, and dendritic cells were main producers of MDC, while T cells produced only a small amount of MDC. MDC production by B cells was equally stimulated by LPS and anti-CD40 Ab, while that by macrophages and dendritic cells was more markedly stimulated by anti-CD40 Ab, and PGE(2) further enhanced MDC production by these stimulated cells. These results indicate that PGE(2) regulates Th1/Th2-related chemokine production by B cells, macrophages, and dendritic cells, and that this is a new function of PGE(2) for the regulation of Th2 immune responses at the induction and activation stages.

The effects of histamine on interferon gamma production are dependent on the stimulatory signals

Histamine regulates the immune response by enhancing TH2 cytokine production and by inhibiting TH1 cytokine production. We assessed the mechanisms of histamine's action on helper T cell subsets by evaluating the role of protein kinase A (PKA) in the histamine-mediated effects on IFN gamma production. The splenocytes and TH1 murine cloned cells (pGL10) were pretreated with histamine at a concentration range of 10(-8)-10(-5) M for 1 h and then were activated with anti-CD3, PHA, PMA + ionomycin, or ionomycin for 24 h. The levels of IFN gamma were measured in the supernatants by ELISA. The inhibitory effects of histamine were the most prominent in anti-CD3-stimulated splenocytes (61%). The effects of histamine on IFN gamma production from TH1 cells depended on the mode of cell activation. The activation of cells with anti-CD3 resulted in 27% inhibition of IFN gamma production whereas the activation with ionomycin produced 70% suppression. The inhibitory effects of histamine were completely reversed by cimetidine in a dose-dependent manner in both TH1 cells and in splenocytes. PKA played a role in the inhibition of IFN gamma by histamine when the cells were activated via TCR, and the PKA inhibitors Rp-cAMPS (10(-5) M) and H8 (10(-5) M) reversed the inhibitory effects of histamine on IFN gamma production. However, when the cells were stimulated with ionomycin, the PKA inhibitors did not affect histamine-mediated suppression of IFN gamma production.

Immunological principles of adverse drug reactions: the initiation and propagation of immune responses elicited by drug treatment

Adverse drug reactions account for between 2 to 5% of all hospital admissions and can prevent the administration of an otherwise effective therapeutic agent. Hypersensitivity or immune-mediated reactions, although less common, tend to be proportionately more serious. There is convincing evidence to implicate the immune system in the pathogenesis of hypersensitivity reactions. Our understanding of the way in which the immune system recognises drugs is based on the hapten hypothesis; the onset of hypersensitivity involves drug bioactivation, covalent binding to proteins, followed by uptake, antigen processing and T cell proliferation. Central to this hypothesis is the critical role of drug metabolism, with the balance between metabolic bioactivation and detoxification being one important component of individual susceptibility. The purpose of this review is to classify drug hypersensitivity reactions in terms of their clinical presentation, and also to consider recent advances in our understanding of the chemical, biochemical and, in particular, cellular immunological mechanisms of hypersensitivity. The following topics are reviewed: (i) drug disposition and cellular metabolism; (ii) mechanisms of antigen processing and presentation; (iii) the role of cytokines and co-stimulatory molecules in the induction and maintenance of a polarised immune response; and (iv) the application of the hapten hypothesis, danger hypothesis and serial triggering model to drug hypersensitivity. A greater understanding of the mechanism(s) of hypersensitivity may identify novel therapeutic strategies and help to combat one of the more severe forms of adverse reactions to drugs.

Suppression of gamma interferon transcription and production by nematode excretory-secretory antigen during polyclonal stimulation of rat lymph node T cells

Although certain helminth infections preferentially induce type 2 T-cell responses, the immunological mechanisms responsible for type 2 T-cell polarization remain unclear. In the present study, we investigated the effects of excretory-secretory (ES) antigen from the nematode Nippostrongylus brasiliensis on cytokine production by mesenteric lymph node (MLN) cells isolated from naive rats. MLN cells produced considerable levels of gamma interferon (IFN-gamma) during a 72-h stimulation with concanavalin A (ConA) or with immobilized anti-CD3 plus soluble anti-CD28 antibodies (anti-CD3/CD28). With either stimulation, 10 microg of ES antigen per ml significantly suppressed IFN-gamma and interleukin-2 (IL-2) production without cytotoxic activity. The copresence of anti-IL-4, anti-IL-10, or transforming growth factor beta (TGF-beta) blocking antibodies did not alter the suppressive effect of ES antigen on IFN-gamma production. ES antigen did not affect IL-10 production. Kinetic studies of the effect of ES antigen indicated that the antigen suppressed even ongoing IFN-gamma production. Reverse transcription-PCR study showed that in the presence of ES antigen, IFN-gamma mRNA expression by MLN cells was suppressed 6 and 12 h after ConA or anti-CD3/CD28 stimulation. ES antigen also significantly suppressed IFN-gamma production by purified CD4(+) or CD8(+) T cells during anti-CD3/CD28 stimulation but did not affect IL-4 production by CD4(+) T cells. These findings suggested that the nematode antigen suppressed production of IFN-gamma and IL-2 but not IL-4 or IL-10 production. ES antigen-mediated suppression of IFN-gamma during the initiation of the immune response may provide a microenvironment that helps generation of type 2 T cells.

Immunology at the maternal-fetal interface: lessons for T cell tolerance and suppression

Mammalian reproduction poses an immunological paradox because fetal alloantigens encoded by genes inherited from the father should provoke responses by maternal T cells leading to fetal loss. Current understanding of T cell immunobiology and the critical role of inflammatory processes during pregnancy is reviewed and discussed. Lessons derived from studies on the regulation of T cell responsiveness during mammalian gestation are considered in the wider context of T cell tolerance toward some microbial infections and tumors, avoidance of autoimmunity, and tissue allograft rejection.

Innate immune responses in children and adults with Shigellosis

An array of pro- and anti-inflammatory mediators of the innate immune system was analyzed in stool, urine, and rectal mucosa samples from adults and children with shigellosis to better understand their role in recovery from and in the immunopathogenesis of the disease. Increased concentrations of lactoferrin (Lf), myeloperoxidase (MPO), prostaglandin E(2), and leukotriene B(4) (LTB(4)) in stool during acute shigellosis in both children and adults indicated that activated cells of the innate defense system at the mucosal site were secreting the mediators. Increased concentration of MPO and 8-iso-prostaglandin F(2alpha) and lower levels of superoxide dismutase (SOD) activity in stool during acute Shigella infection suggested increased formation of reactive oxygen species, free radical-catalyzed peroxidation of membrane lipids, and decreased scavenging of the reactive oxygen radicals. In children, lower expression of SOD in tissue with severe inflammation and lower levels of SOD activity in stool for longer periods compared to adults may further worsen the tissue damage and predispose the children to a lowered defense. Both adult and pediatric patients had significantly higher expression of inducible nitric oxide synthase (iNOS) in the rectum with severe inflammation, compared to that seen with mild inflammation, accompanied by persistently up-regulated iNOS mRNA, reflecting increased production of nitric oxide at the local site. However, in contrast to adults, reduced urinary nitrate levels in pediatric patients during acute shigellosis suggested lower production of nitric oxide in the renal compartment. Persistent production of Lf in pediatric patients may contribute to chronic inflammation in the rectum. In addition, increased production of proinflammatory mediators in the rectum of patients with severe histology suggested contribution of these molecules to the immunopathogenesis of severe colitis caused by shigellae.

Regulation of immunoglobulin G2 production by prostaglandin E(2) and platelet-activating factor

Patients with localized juvenile periodontitis (LJP) have elevated levels of immunoglobulin G2 (IgG2) in their sera. This is also observed in vitro when peripheral blood leukocytes from LJP patients are stimulated with pokeweed mitogen. In previous studies, we showed that lymphocytes from subjects with no periodontitis (NP subjects) produced substantial amounts of IgG2 when they were cultured with monocytes from LJP patients (LJP monocytes). These observations indicate that monocytes or monocyte-derived mediators are positive regulators of the production of IgG2. The present study was initiated to determine if secreted factors from LJP monocytes were capable of enhancing IgG2 production and to determine if prostaglandin E2 (PGE(2)), which LJP monocytes produce at elevated levels, enhances IgG2 production. Experiments in a transwell system and with monocyte-conditioned media indicated that cell-cell contact was not necessary for LJP monocytes to augment the production of IgG2 by T and B cells from NP subjects. Moreover, the production of IgG2 was selectively induced by the addition of PGE(2) or platelet-activating factor (PAF), another lipid cytokine, which can elevate PGE(2) synthesis. Furthermore, IgG2 production was abrogated when cells were treated with indomethacin, a cyclooxygenase inhibitor that blocks the synthesis of PGE(2), or the PAF antagonists CV3988 and TEPC-15. The effects of indomethacin were completely reversed by PGE(2), indicating that this is the only prostanoid that is essential for the production of IgG2. Similarly, PGE(2) reversed the effects of a PAF antagonist, suggesting that the effects of PAF are mediated through the induction of PGE(2) synthesis. Together, these data indicate that PGE(2) and PAF are essential for the production of IgG2.

Hypomethylation of the proximal and intronic regulatory regions of the IFN-gamma gene is not essential for its transcription by naive CD4+ T cells cultured with IL-4

Recently, long-term preculture with IL-4 or IL-7 has been reported to induce IFN-gamma-producing ability in naive CD4+ T cells without stimulation via TCR. The mechanism of IFN-gamma-transcription in naive CD4+ T cells precultured with IL-4 was analyzed and compared with that in typical Th1 cells by focusing on the TATA proximal and first intronic regulatory regions of the IFN-gamma gene. Both regulatory regions in these IL-4-primed naive CD4+ T cells, which produce a large amount of IFN-gamma upon stimulation with PMA and ionomycin, were completely methylated in contrast to the same hypomethylated regions in Th1 cells. DNase I hypersensitive site analysis suggested that both regulatory regions in IL-4-primed naive CD4+ T cells were not active for IFN-gamma-expression. Moreover, we demonstrated that the composition of transcriptional factors that can bind to the proximal regulatory region is different between IL-4-primed naive CD4+ T cells and Th1 cells. These results indicated that the transcriptional machinery involved in the expression of the IFN-gamma gene by CD4+ T cells varied depending on their modes of differentiation in both the responsive regulatory regions and the specific nuclear factors.