Identification of a peptide inducing experimental autoimmune uveoretinitis (EAU) in H-2Ak-carrying mice

Involvement of Angiopoietin 2 and vascular endothelial growth factor in uveitis

PURPOSE

Angiopoietin (Ang) 2 is released from vascular endothelial cells by the stimulation of vascular endothelial growth factor (VEGF)A. Ang2 increases the expression of leukocyte adhesion molecules on endothelial cells via nuclear factor κB. The aim of this study was to evaluate the effects of Ang2 and VEGFA on ocular autoimmune inflammation.

METHODS

We measured the concentrations of Ang2 and VEGFA in vitreous samples among patients with uveitis. Vitreous samples were collected from 16 patients with idiopathic uveitis (uveitis group) and 16 patients with non-inflammatory eye disease (control group). Experimental autoimmune uveoretinitis (EAU) was induced in B10.BR mice with a human interphotoreceptor retinoid-binding protein-derived peptide. The retinochoroidal tissues of the EAU mice were removed, and the mRNA levels of Ang2 and VEGFA were examined. EAU mice treated with anti-Ang2, anti-VEGFA, a combination of anti-Ang2 and anti-VEGFA, anti-Ang2/VEGFA bispecific, or IgG control antibodies were clinically and histopathologically evaluated.

RESULTS

The protein levels of Ang2 and VEGFA were significantly higher in the vitreous samples of patients with uveitis than in controls (P<0.05). The retinochoroidal mRNA levels of Ang2 and VEGFA were significantly upregulated in EAU mice compared to controls (n = 6, P<0.05). Although there was no significant difference, treatment with anti-VEGFA antibody reduced the clinical and histopathological scores. However, treatment with anti-Ang2 antibody reduced the clinical and histopathological scores (n = 18-20, P<0.05). Furthermore, these scores were further decreased when treated by inhibiting both Ang2 and VEGFA.

CONCLUSIONS

Based on these results, VEGFA and Ang2 were shown to be upregulated locally in the eye of both uveitis patients and models of uveitis. Dual inhibition of Ang2 and VEGFA is suggested to be a new therapeutic strategy for uveitis.

Engrafted Neural Progenitor Cells Express a Tissue-Restricted Reporter Gene Associated with Differentiated Retinal Photoreceptor Cells

Neural progenitor cells (NPCs) have shown ability to repair injured CNS, and might provide precursors to retinal neurons. NPCs were isolated from the brains of 14 day murine embryos of transgenic mice that express β-galactosidase (β-gal) on the arrestin promoter, which specifically directs expression to retinal photoreceptor cells. NPCs were transferred to adult, syngeneic mice via inoculation into the anterior chamber of the eye, the peritoneal cavity, or the brain. At 14 weeks postgrafting, tissues were collected and examined to determine if differentiated NPC progeny were present in retina based on histochemical detection of β-gal. Four of six anterior chamber-inoculated recipients showed Bluo-gal-stained cells in retina, indicating the presence of transferred NPCs or their progeny. Because the progenitor cells do not express β-gal, positive staining indicates differentiation leading to activation of the arrestin promoter. Two recipients inoculated by the intraperitoneal route also exhibited Bluo-gal staining in retina. The NPCs did not express β-gal if inoculated into brain, but survived and dispersed. Most recipients, regardless of inoculation route, were PCR positive for β-gal DNA in extraocular tissues, but no Bluo-gal staining was found outside of the retina. Injury to the retina promoted, but was not required, for progenitor cell engraftment. β-Gal-positive cells were concentrated in the outer layers of the retina. In summary, a reporter gene specifically expressed in differentiated retinal photoreceptor cells due to the activity of the arrestin promoter was expressed in recipient mouse retina following transfer of NPCs prepared from the β-gal transgenic mice. The presence of β-gal DNA, but not Bluo-gal staining, in spleen and other tissues revealed that the cells also migrated elsewhere and took up residence in other organs, but did not undergo differentiation that led to β-gal expression.

Environmental microbes and uveitis: is microbial exposure always bad?

The eye generally is considered to be an immune-privileged organ, but this notion is being increasingly challenged as ocular antigens can be expressed in the generative lymphoid organs, resulting in attainment of self-tolerance. What triggers a break in this tolerant state is a fundamental question in autoimmunity research. The general belief is that exposure to environmental microbes can break self-tolerance in genetically susceptible individuals, leading to the induction of autoimmune responses. The molecular mimicry hypothesis has been proposed as one major mechanistic, pathway through which microbes, by generating cross-reactive immune responses, can induce ocular damage of the kind that might occur in uveitis. However, our recent data suggest that exposure to microbial products containing mimicry epitopes for retinal antigens can potentially be beneficial to the host. In this review, we discuss the immune mechanisms with particular reference to the molecular mimicry hypothesis as it relates to immune-mediated uveitis.

Amelioration of experimental autoimmune uveoretinitis by inhibition of glyceraldehyde-derived advanced glycation end-product formation

AGEs are permanently modified macromolecule derivatives that form through nonenzymatic glycation of amino groups of proteins. Glycer-AGEs are highly toxic and play an important role in the pathogenesis of chronic inflammatory diseases. However, the contribution of glycer-AGEs to the pathogenesis of uveitis is unclear. In this study, we measured serum levels of glycer-AGEs in 100 patients with endogenous uveitis (22 with HLA-B27-associated uveitis, 20 with VKH disease, 14 with Behçet's disease, and 44 with sarcoidosis) and 33 healthy volunteers. We then examined the effect of the AGE inhibitor in a mouse model of human endogenous uveitis (EAU) by continuous oral administration of pyridoxamine at 200 or 400 mg/kg/day. Regardless of the etiology, serum glycer-AGE levels were significantly higher in patients with uveitis than in healthy subjects. Treatment with 400 mg/kg pyridoxamine significantly reduced the clinical and histological severity of EAU and was accompanied by a significant decrease in serum and retinal glycer-AGE levels and suppression of translocation of NF-κB p65 into the nucleus of retinal cells. Serum glycer-AGE levels may therefore serve as a biomarker of human uveitis, as well as systemic inflammation, and may contribute to the progression of uveitis, including diabetic iritis, via the activation of NF-κB.

Mimicry epitope from Ehrlichia canis for interphotoreceptor retinoid-binding protein 201-216 prevents autoimmune uveoretinitis by acting as altered peptide ligand

We report here identification of novel mimicry epitopes for interphotoreceptor retinoid-binding protein (IRBP) 201-216, a candidate ocular antigen that causes experimental autoimmune uveoretinitis (EAU) in A/J mice. One mimicry epitope from Ehrlichia canis (EHC), designated EHC 44-59, induced cross-reactive T cells for IRBP 201-216 capable of producing T helper (Th)1 and Th17 cytokines, but failed to induce EAU in A/J mice. In addition, animals first primed with suboptimal doses of IRBP 201-216 and subsequently immunized with EHC 44-59 did not develop EAU; rather, the mimicry epitope prevented the disease induced by IRBP 201-216. However, alteration in the composition of EHC 44-59 by substituting alanine with valine at position 49, similar to the composition of IRBP 201-216, enabled the mimicry epitope to acquire uveitogenicity. The data provide new insights as to how microbes containing mimicry sequences for retinal antigens can prevent ocular inflammation by acting as naturally occurring altered peptide ligands.

Uveitis in mouse and man

Uveitis is underappreciated as a sight-threatening cause of blindness. There are two broad causative classes of uveitis: infectious and non-infectious. Non-infectious uveitis is considered a prototypical autoimmune disorder based mainly on data from experimental models in the mouse. Several different experimental models exist that reflect the different types of uveitis in man (anterior, intermediate, and posterior uveitis). These models have demonstrated that uveitis is predominantly a Th1/Th17 mediated disease, although innate immune cells play a significant role both in induction of disease and in tissue damage. Most experimental models of uveitis rely on activation of the innate immune system by use of adjuvants that activate a range of pathogen recognition receptors (PRRs). This begs the question of the underlying role of initial and/or persistent infection, including latent infection, in immune-mediated uveitis in which active infection cannot be demonstrated. This further raises the possibility of pathogenic mechanisms such as antigenic cross-reactivity and molecular mimicry. Alternatively, residual/latent antigen from infectious agents may act as "endogenous" adjuvants for induction of immune reactions to damaged/altered self antigen, suggesting a commonality in pathogenesis for both infectious and non-infectious uveitis in man.

Coxsackievirus B3 infection leads to the generation of cardiac myosin heavy chain-α-reactive CD4 T cells in A/J mice

Enteroviruses like coxsackievirus B3 (CVB3) are common suspects in myocarditis/dilated cardiomyopathy patients. Autoimmunity has been proposed as an underlying mechanism, but direct evidence of its role is lacking. To delineate autoimmune response in CVB3 myocarditis, we used IA(k) dextramers for cardiac myosin heavy chain (Myhc)-α 334-352. We have demonstrated that myocarditis-susceptible A/J mice infected with CVB3 generate Myhc-α-reactive CD4 T cells and such a repertoire was absent in naïve mice as measured by proliferative response to Myhc-α 334-352 and IA(k) dextramer staining. We also detected Myhc-α 334-352 dextramer(+) cells in the hearts of CVB3-infected mice. The autoreactive T cell repertoire derived from infected mice contained a high frequency of interleukin-17-producing cells capable of inducing myocarditis in naïve recipients. The data suggest that CVB3, a bona fide pathogen of cardiovascular system that primarily infects the heart can lead to the secondary generation of autoreactive T cells and contribute to cardiac pathology.

Mesenchymal stem cells induce functionally active T-regulatory lymphocytes in a paracrine fashion and ameliorate experimental autoimmune uveitis

PURPOSE

Mesenchymal stem/progenitor cells (MSCs) have regenerative and immunomodulatory properties, exerted by cell-cell contact and in a paracrine fashion. Part of their immunosuppressive activity has been ascribed to their ability to promote the induction of CD4+CD25+FoxP3+ T lymphocytes with regulatory functions (Treg). Here the authors studied the effect of MSCs on the induction of Treg and on the development of autoimmunity, and they examined the possibility that MSC-mediated Treg induction could be attributed to the secretion of soluble factors.

METHODS

The authors induced experimental autoimmune uveitis (EAU) in mice by immunization with the 1-20 peptide of the intraphotoreceptor binding protein. At the same time, some of the animals were treated intraperitoneally with syngeneic MSCs. The authors checked T-cell responses and in vitro Treg conversion by cell proliferation and blocking assays, in cell-cell contact and transwell settings. TGFβ and TGFβ receptor gene expression analyses were performed by real-time PCR.

RESULTS

The authors found that a single intraperitoneal injection of MSCs was able to significantly attenuate EAU and that a significantly higher percentage of adaptive Treg was present in MSC-treated mice than in MSC-untreated animals. In vitro blocking of antigen presentation by major histocompatibility complex class II precluded priming and clonal expansion of antigen-specific Treg, whereas blockade of TGFβ impaired the expression of FoxP3, preventing the conversion of CD4+ T cells into functionally active Treg.

CONCLUSIONS

The authors demonstrated that MSCs can inhibit EAU and that their immunomodulatory function is due at least in part to the induction of antigen-specific Treg in a paracrine fashion by secreting TGFβ.

Rodent models of experimental autoimmune uveitis

The model of experimental autoimmune uveitis (EAU) in mice and in rats is described. EAU targets immunologically privileged retinal antigens and serves as a model of autoimmune uveitis in humans as well as a model for autoimmunity in a more general sense. EAU is a well-characterized, robust, and reproducible model that is easily followed and quantitated. It is inducible with synthetic peptides derived from retinal autoantigens in commonly available strains of rats and mice. The ability to induce EAU in various gene-manipulated, including HLA-transgenic, mouse strains makes the EAU model suitable for the study of basic mechanisms as well as in clinically relevant interventions.

Experimental autoimmune uveoretinitis in the rat and mouse

Experimental autoimmune uveoretinitis (EAU) in rats and mice is a prototypic T cell-mediated autoimmune disease that targets the neural retina and related tissues. The model is used to represent human sight-threatening inflammatory eye diseases that are believed to have an autoimmune etiology, and to study basic mechanisms of tolerance and autoimmunity to organ-specific antigens from immunologically privileged sites. In this unit, EAU is induced in rats and mice by immunization with uveitogenic peptide antigens emulsified in complete Freund's adjuvant (CFA). Clinical onset is observed by both external and microscopic examination. A protocol is provided for preparation of tissue sections of affected eyes for microscopic analysis. EAU can also be induced in the rat (as described) by adoptive transfer of lymphocytes from uveitic rats into unimmunized recipients, which obviates the use of CFA. To induce EAU in mice, Bordetella pertussis toxin (PTX) is included to overcome immunological resistance mechanisms.

Mouse models of experimental autoimmune uveitis

The mouse model of experimental autoimmune uveitis, induced by immunization of mice with the retinal protein IRBP, was developed in our laboratory 20 years ago and published in 1988. Since that time it has been adopted by many investigators and has given rise to many studies that helped elucidate genetic influences, dissect the basic mechanisms of pathogenesis and test novel immunotherapeutic paradigms. The current overview will summarize the salient features of the experimental autoimmune uveitis model and discuss its mechanisms.

Anti-inflammatory property of the cannabinoid receptor-2-selective agonist JWH-133 in a rodent model of autoimmune uveoretinitis

Previous studies have shown that cannabinoids have anti-inflammatory and immune-modulating effects, but the precise mechanisms of action remain to be elucidated. In this study, we investigated the effect of JWH 133, a selective agonist for cannabinoid receptor 2, the main receptor expressed on immune cells, in a model of autoimmune disease, experimental autoimmune uveoretinitis (EAU). JWH 133 suppressed EAU in a dose-dependent manner (0.015-15 mg/kg), and the suppressive effect could be achieved in the disease-induction stage and the effector stage. Leukocytes from mice, which had been treated with JWH 133, had diminished responses to retinal peptide and mitogen Con A stimulation in vitro. In vivo JWH 133 treatment also abrogated leukocyte cytokine/chemokine production. Further in vitro studies indicated that JWH 133 down-regulated the TLR4 via Myd88 signal transduction, which may be responsible for its moderate, suppressive effect on antigen presentation. In vivo JWH 133 treatment (1 mg/kg) also suppressed leukocyte trafficking (rolling and infiltration) in inflamed retina as a result of an effect on reducing adhesion molecules CD162 (P-selectin glycoprotein ligand 1) and CD11a (LFA-1) expression on T cells. In conclusion, the cannabinoid agonist JWH 133 has a high in vivo, anti-inflammatory property and may exert its effect via inhibiting the activation and function of autoreactive T cells and preventing leukocyte trafficking into the inflamed tissue.

Mechanisms for inducing nasal mucosal tolerance in experimental autoimmune uveoretinitis

Delivering soluble (auto) antigenic peptides via the naso-respiratory route induces tolerance to that peptide and suppression of experimental models of autoimmune disease. In the normal lung, respiratory tract dendritic cells (RTDCs) efficiently endocytose soluble antigens, migrate to regional lymph nodes and present peptide to T cells that subsequently become tolerant. This article describes protocols for inducing tolerance via the naso-respiratory tract in experimental autoimmune uveoretinitis (EAU); for the isolation of RTDCs to facilitate definition of, and conditions for, maturation and activation of cells; and to test RTDC ability to induce tolerance in murine EAU when adoptively transferred.

Severe chronic experimental autoimmune uveitis (EAU) of the C57BL/6 mouse induced by adoptive transfer of IRBP1–20-specific T cells

Experimental autoimmune uveitis (EAU) can be induced in susceptible mice by immunization with retinal antigens. The response to uveitogens is genetically restricted. B10RIII and B10A mouse are highly susceptible to IRBP-induced uveitis, whereas B6 mouse is less susceptible. Immunization to B6 mouse with IRBP only induced very mild disease with low incidence. However, the susceptibility can be enhanced by transferring activated IRBP-specific T cells. In this study, we show that a reproducible and severe uveitis can be induced in B6 mice by adoptive transfer of IRBP-specific T cells. The disease incidence, severity, and duration can be readily controlled by the number and activation status of the injected T cells. Both CD4(+)- and CD8(+) IRBP1-20-specific T cells were identified in vitro IRBP peptide stimulation. In addition, IRBP1-20-specific T cells were consistently detected in recipient mice for up to 2 months, but only detected in the acute phase of the disease in actively immunized mice, indicating that persistency of injected IRBP1-20-specific T cells in recipient B6 mice might be one of the mechanisms causing chronic and severe disease. Giving that a large number of transgenic and KO mice are available in B6 background, an improved uveitis model in B6 mouse should assist the determination of pathogenesis of disease and identify molecules that can be targeted by new therapies.

Inducible immune regulation following autoimmune disease in the immune-privileged eye

The immune-privileged eye has the potential to induce regulatory immunity along with local mechanisms of immunosuppression. Rodent models of human autoimmune uveoretinitis [experimental autoimmune uveoretinitis (EAU)] recover without spontaneous recurrence of uveitis, which differs from uveitis in some humans. This raises the possibility that the mechanism of immune privilege in the rodent eye can reimpose itself during autoimmune uveoretinitis and re-establish tolerance to autoantigen. To investigate this possibility, we examined the spleens of EAU-recovered mice for regulatory immunity. We detected regulatory immunity when we adoptively transferred post-EAU spleen cells into other mice immunized for EAU. We could not detect this regulatory immunity in enucleated mice nor in naive mice. Moreover, unlike the mechanisms of anterior chamber-associated immune deviation, the suppression was only mediated by post-EAU CD4+ T cells, which required activation with autoantigen presented by post-EAU spleen antigen-presenting cells (APC). Our results demonstrate that when the immune-privileged ocular microenvironment recovers from an autoimmune response, it has influenced systemic immunity to retinal autoantigen by affecting APC and mediating induction of potential regulatory CD4+ T cells laying in wait in the post-EAU spleen for restimulation.

Reduction in shear stress, activation of the endothelium, and leukocyte priming are all required for leukocyte passage across the blood--retina barrier

The passage of leukocytes across the blood-retina barrier at the early stages of an inflammatory reaction is influenced by a complex series of interactions about which little is known. In particular, the relationship between hydrodynamic factors, such as shear stress and leukocyte velocity, to the adherence and subsequent extravasation of leukocytes into the retina is unclear. We have used a physiological method, scanning laser ophthalmoscopy, to track labeled leukocytes circulating in the retina, followed by confocal microscopy of retinal flatmounts to detect infiltrating cells at the early stage of experimental autoimmune uveitis. This has shown that retinal vessels are subjected to high shear stress under normal circumstances. During the inflammatory reaction, shear stress in retinal veins is reduced 24 h before leukocyte infiltration. This reduction is negatively correlated with leukocyte rolling and sticking in veins and postcapillary venules, the sites of leukocyte extravasation. Activation of vascular endothelial cells is also a prerequisite for leukocyte rolling and infiltration. In addition, antigen priming of leukocytes is influential at the early stage of inflammation, and this is seen clearly in the reduction in rolling velocity and adherence of the primed leukocytes in activated retinal venules, 9 days postimmunization.

The suppressive effect of triptolide on experimental autoimmune uveoretinitis by down-regulating Th1-type response

We investigated the suppressive effect of triptolide (TRD), a purified component from a traditional Chinese herb, Tripterygium wilfordii Hook F. (TWHf), on uveitogenic peptide (K2)-induced experimental autoimmune uveoretinitis (EAU). K2-peptide immunized B10.A mice were divided into four groups. One group was EAU control which was treated with PBS. The other two groups were treated with TRD with different time courses (from day 0 to day 28 and from day 14 to day 28). The last group was treated with Cyclosporin A (CsA) as a positive control of the treatment. TRD was administered at dose of 0.1 mg/kg/day (i.p.). CsA was administered at dose of 20 mg/kg/day (i.p.) from day 0 to day 28 during whole period of EAU induction. The data showed that the EAU was suppressed in the whole period of TRD-treated mice, but was not in TRD-treated mice from day 14 to day 28 following immunization. The inhibition of EAU induced by TRD treatment was comparable to CsA-treated mice. The K2-specific lymphocyte proliferation and mRNA expressions of Th1-type cytokines (IL-12p40, IFN-gamma and TNF-alpha) in draining lymph node and inflamed eyes were reduced in TRD-treated mice. The K2-specific IFN-gamma production in the draining lymph node cells (LNC) of TRD-treated mice (whole period) was significantly inhibited. This effect was not related to an apoptotic effect of TRD on CD4+ T cells. Our results suggested that TRD suppressed the induction of EAU by down-regulating Th1-type response in B10.A mice. This preventive effect on EAU induction may be related to the inhibition of TRD on T cell priming and activation.

Immunoregulatory role of ocular macrophages: the macrophages produce RANTES to suppress experimental autoimmune uveitis

Murine experimental autoimmune uveitis (EAU) is a model of human uveitis. Ocular-infiltrating macrophages play a crucial role in the generation of tissue damage in EAU. In fact, several chemokines are actually produced in the inflamed eye. The aim of this study was to elucidate the role of ocular macrophage-derived chemokines in EAU. C57BL/6 mice were immunized with human interphotoreceptor retinoid binding protein peptide 1-20, and the EAU severity was scored at multiple time points based on microscopic fundus observations (retinal vascular dilatation and exudates) and histological examinations. The peak inflammatory response was observed 1 wk (day 16) after the beginning of macrophage infiltration to the eye (day 9). Ocular-infiltrating cells were enriched or depleted of macrophages by magnetic beads and analyzed by real-time RT-PCR for chemokine mRNA production. We found that only the macrophage-enriched cells from the eye produced RANTES, and thus proposed that macrophage-derived RANTES facilitated the ocular inflammations. In contrast to our postulate, neutralization of RANTES by specific Ab in vivo on days 9 and 13 exacerbated EAU. We also found that the ratio of ocular CD4/CD8 T cells was markedly increased after treatment. As a result, RANTES neutralization might exacerbate EAU by modulating the type of T cell subsets recruited to the eye. In conclusion, our data provide insight into the immunoregulatory role of macrophages and RANTES in the pathogenesis of ocular inflammation. Not all macrophage-derived chemokines cause local inflammation, since RANTES produced by ocular macrophages appears to suppress EAU.

Tumour necrosis factor-alpha but not lipopolysaccharide enhances preference of murine dendritic cells for Th2 differentiation

Using murine spleen-derived dendritic cells (DC) and DO11.10 T cells specific for ovalbumin (OVA), the influences of maturational condition and antigen dose on the capability of DC to induce helper T-cell (Th) differentiation were analysed. Immature DC (iDC) with high- or low-dose OVA(323-339) predominantly induced Th1 or Th2 responses in DO11.10 T cells, respectively. DC matured by tumour necrosis factor-alpha (TNF/DC) induced a significantly higher Th2 response in the presence of low-dose OVA(323-339) than iDC and DC matured by lipopolysaccharide (LPS) (LPS/DC). In the presence of high-dose OVA(323-339), LPS/DC induced significantly lower levels of Th1 response than iDC. Under these conditions no difference in the Th1 response was noted between TNF/DC and iDC. The enhanced capability of TNF/DC with a low-dose antigen for Th2 polarization and the decreased preference of LPS/DC with a high-dose antigen to Th1 polarization were not related to the amount of IL-12 produced in these cultures. These results demonstrate for the first time that TNF/DC with a low-dose antigen are potent inducers of Th2 differentiation.

Amelioration of experimental autoimmune uveoretinitis by pretreatment with a pathogenic peptide in liposome and anti-CD40 ligand monoclonal antibody

We have defined a peptide K2 (ADKDVVVLTSSRTGGV) that corresponds to residues 201-216 of bovine interphotoreceptor retinoid-binding protein and induces experimental autoimmune uveoretinitis (EAU)4 in H-2Ak-carrying mice (H-2Ak mice). In this study, we attempted to ameliorate EAU in the H-2Ak mice without nonspecific suppression of T cell responses. Preceding s.c. administration of liposomes including K2 (liposomal K2) specifically inhibited subsequent generation of T cell response to K2. The same result was obtained with a combination of OVA323-339 peptide and the OVA-specific TCR-transgenic T cells. It was suggested that the inhibition was mainly attributed to peripheral anergy induction of T cells specific for the peptide Ag, although specific cell death might also be involved in the inhibition. Pretreatment with liposomal K2 also considerably abolished IFN-gamma production but not IL-4 production. The specific inhibitory effect of the pretreatment with liposomal peptide was augmented by a simultaneous administration of anti-CD40 ligand (anti-CD40L) mAb. Moreover, it was shown that the pretreatment with liposomal K2 reduced both the incidence and severity of the subsequent K2-induced EAU, and the simultaneous administration of anti-CD40L mAb augmented this preventive effect by liposomal K2. Our findings demonstrate that the s.c. administration of liposomal pathogenic peptide and anti-CD40L mAb can be applied to preventing autoimmune diseases without detrimental nonspecific suppression of T cell responses.

Different influence of macrophage migration inhibitory factor (MIF) in signal transduction pathway of various T cell subsets

It has been shown that macrophage migration inhibitory factor (MIF) modulates not only macrophage functions, but also T cell functions. However, detailed analysis of the MIF function on responses of various T cell subpopulations remained to be elucidated. In this report, using a neutralizing anti-MIF monoclonal antibody (mAb) we examined MIF functions on various T cell lineages. It was shown that anti-MIF mAb inhibited antigen-specific responses of both IFN-gamma producing and IL-4 producing T cells. The inhibition appeared to be related to blockade of the signal pathway via T cell receptor (TCR) but not that via IL-2 receptor (IL-2R). However, the anti-MIF mAb showed no inhibitory effect on NK-T cell responses stimulated through TCR. These results suggest that MIF is involved in the signal pathway via TCR in mainstream T cells but not in NK-T cells.