Immunomodulatory Properties of Mesenchymal Stromal Cells: Still Unresolved "Yin and Yang".

Mesenchymal stromal cells (MSC) are mesodermal elements characterized by the ability to differentiate into several types of cells present mainly in connective tissues. They play a key function in tissue homeostasis and repair. Furthermore, they exert a strong effect on both innate and adaptive immune response. The main current of thought considers MSC as strong inhibitors of the immune system. Indeed, the first description of MSC immunomodulation pointed out their inability to induce alloimmune responses and their veto effects on mixed lymphocyte reactions. This inhibition appears to be mediated both by direct MSC interaction with immune cells and by soluble factors. Unfortunately, evidence to support this notion comes almost exclusively from in vitro experiments. In complex experimental systems, it has been shown that MSC can exert immunosuppressive effects also in vivo, either in murine models or in transplanted patients to avoid the graft versus host disease. However, it is still debated how the small number of administered MSC can regulate efficiently a large number of host effector lymphocytes. In addition, some reports in the literature indicate that MSC can trigger rather than inhibit lymphocyte activation when a very low number of MSC are co-cultured with lymphocytes. This would imply that the ratio between the number of MSC and immune cells is a key point to forecast whether MSC will inhibit or activate the immune system. Herein, we discuss the conflicting results reported on the immunomodulatory effects of MSC to define which features are relevant to understand their behavior and cross-talk with immune cells.

A Functionally Different Immune Phenotype in Cattle Is Associated With Higher Mastitis Incidence.

A novel vaccine against bovine viral diarrhea (BVD) induced pathogenic antibody production in 5-10% of BVD-vaccinated cows. Transfer of these antibodies via colostrum caused Bovine neonatal pancytopenia (BNP) in calves, with a lethality rate of 90%. The exact immunological mechanisms behind the onset of BNP are not fully understood to date. To gain further insight into these mechanisms, we analyzed the immune proteome from alloreactive antibody producers (BNP cows) and non-responders. After in vitro stimulation of peripheral blood derived lymphocytes (PBL), we detected distinctly deviant expression levels of several master regulators of immune responses in BNP cells, pointing to a changed immune phenotype with severe dysregulation of immune response in BNP cows. Interestingly, we also found this response pattern in 22% of non-BVD-vaccinated cows, indicating a genetic predisposition of this immune deviant (ID) phenotype in cattle. We additionally analyzed the functional correlation of the ID phenotype with 10 health parameters and 6 diseases in a retrospective study over 38 months. The significantly increased prevalence of mastitis among ID cows emphasizes the clinical relevance of this deviant immune response and its potential impact on the ability to fight infections.

Notch signaling mediated by Delta-like ligands 1 and 4 controls the pathogenesis of chronic GVHD in mice.

Chronic graft-versus-host disease (cGVHD) is a major complication of allogeneic hematopoietic cell transplantation (allo-HCT) and remains an area of unmet clinical need with few treatment options available. Notch blockade prevents acute GVHD in multiple mouse models, but the impact of Notch signaling on cGVHD remains unknown. Using genetic and antibody-mediated strategies of Notch inhibition, we investigated the role of Notch signaling in complementary mouse cGVHD models that mimic several aspects of human cGVHD in search of candidate therapeutics. In the B10.D2→BALB/c model of sclerodermatous cGVHD, Delta-like ligand 4 (Dll4)-driven Notch signaling was essential for disease development. Antibody-mediated Dll4 inhibition conferred maximum benefits when pursued early in a preventative fashion, with anti-Dll1 enhancing early protection. Notch-deficient alloantigen-specific T cells showed no early defects in proliferation or helper polarization in vivo but subsequently exhibited markedly decreased cytokine secretion and enhanced accumulation of FoxP3+ regulatory T cells. In the B6→B10.BR major histocompatibility complex-mismatched model with multi-organ system cGVHD and prominent bronchiolitis obliterans (BO), but not skin manifestations, absence of Notch signaling in T cells provided long-lasting disease protection that was replicated by systemic targeting of Dll1, Dll4, or both Notch ligands, even during established disease. Notch inhibition decreased target organ damage and germinal center formation. Moreover, decreased BO-cGVHD was observed upon inactivation of Notch1 and/or Notch2 in T cells. Systemic targeting of Notch2 alone was safe and conferred therapeutic benefits. Altogether, Notch ligands and receptors regulate key pathogenic steps in cGVHD and emerge as novel druggable targets to prevent or treat different forms of cGVHD.

Screening RhoA/ROCK inhibitors for the ability to prevent chronic rejection of mouse cardiac allografts.

BACKGROUND: Chronic rejection of transplanted organs is a major obstacle in organ transplantation. The main symptoms of chronic rejection are vessel occlusion and tissue fibrosis. Macrophages play a crucial role in chronic rejection. We showed previously that RhoA deletion or RhoA/Rock inhibition using Y27632 inhibitor reorganizes macrophage actin cytoskeleton, prevents macrophage movement to the cardiac allografts, and abrogates chronic rejection in rodent models. Although besides Y27632 there are other RhoA/ROCK inhibitors available commercially, their efficacy in inhibition of chronic rejection remains unknown. METHODS: We screened four RhoA/Rock inhibitors for their ability to inhibit chronic rejection of BALB/c [H-2d] mouse cardiac allografts heterotopically transplanted into C57BL/6 [H-2b] recipients. We also tested the effect of inhibitors on macrophages in vitro. RESULTS: We found that out of four tested compounds, the Fasudil and Azaindole, inhibited vessel occlusion, tissue fibrosis, decreased M2 macrophage infiltration and abrogated chronic rejection of mouse cardiac allografts. The remaining inhibitors, SAR-407899 and SLX-2119, decreased only tissue fibrosis, and were ineffective or only slightly effective in inhibiting vessel occlusion. We also found that Azaindole and Fasudil affected actin cytoskeleton and protein expression in mouse peritoneal macrophages CONCLUSION: Results of these studies might help in development of anti-chronic rejection therapy for clinical use.

Immunocontraceptive target repertoire defined by systematic identification of sperm membrane alloantigens in a single species.

Sperm competence in animal fertilization requires the collective activities of numerous sperm-specific proteins that are typically alloimmunogenic in females. Consequently, sperm membrane alloantigens are potential targets for contraceptives that act by blocking the proteins' functions in gamete interactions. Here we used a targeted proteomics approach to identify the major alloantigens in swine sperm membranes and lipid rafts, and thereby systematically defined the repertoire of these sperm-specific proteins in a single species. Gilts with high alloantibody reactivity to proteins in sperm membranes or lipid rafts produced fewer offspring (73% decrease) than adjuvant-only or nonimmune control animals. Alloantisera recognized more than 20 potentially unique sperm membrane proteins and five sperm lipid raft proteins resolved on two-dimensional immunoblots with or without prior enrichment by anion exchange chromatography. Dominant sperm membrane alloantigens identified by mass spectrometry included the ADAMs fertilin α, fertilin ß, and cyritestin. Less abundant alloantigens included ATP synthase F1 ß subunit, myo-inositol monophosphatase-1, and zymogen granule membrane glycoprotein-2. Immunodominant sperm lipid raft alloantigens included SAMP14, lymphocyte antigen 6K, and the epididymal sperm protein E12. Of the fifteen unique membrane alloantigens identified, eleven were known sperm-specific proteins with uncertain functions in fertilization, and four were not previously suspected to exist as sperm-specific isoforms. De novo sequences of tryptic peptides from sperm membrane alloantigen "M6" displayed no evident homology to known proteins, so is a newly discovered sperm-specific gene product in swine. We conclude that alloimmunizing gilts with sperm membranes or lipid rafts evokes formation of antibodies to a relatively small number of dominant alloantigens that include known and novel sperm-specific proteins with possible functions in fertilization and potential utility as targets for immunocontraception.

Heterogeneity of Human Neutrophil CD177 Expression Results from CD177P1 Pseudogene Conversion.

Most humans harbor both CD177neg and CD177pos neutrophils but 1-10% of people are CD177null, placing them at risk for formation of anti-neutrophil antibodies that can cause transfusion-related acute lung injury and neonatal alloimmune neutropenia. By deep sequencing the CD177 locus, we catalogued CD177 single nucleotide variants and identified a novel stop codon in CD177null individuals arising from a single base substitution in exon 7. This is not a mutation in CD177 itself, rather the CD177null phenotype arises when exon 7 of CD177 is supplied entirely by the CD177 pseudogene (CD177P1), which appears to have resulted from allelic gene conversion. In CD177 expressing individuals the CD177 locus contains both CD177P1 and CD177 sequences. The proportion of CD177hi neutrophils in the blood is a heritable trait. Abundance of CD177hi neutrophils correlates with homozygosity for CD177 reference allele, while heterozygosity for ectopic CD177P1 gene conversion correlates with increased CD177neg neutrophils, in which both CD177P1 partially incorporated allele and paired intact CD177 allele are transcribed. Human neutrophil heterogeneity for CD177 expression arises by ectopic allelic conversion. Resolution of the genetic basis of CD177null phenotype identifies a method for screening for individuals at risk of CD177 isoimmunisation.

Hemolytic disease of the fetus and newborn caused by anti-Lan.

BACKGROUND: Antibodies to the high-incidence red blood cell (RBC) antigen Lan (Langereis) are typically immunoglobulin G and have been shown to fix complement and cause hemolysis of Lan antigen-positive RBCs. Only three cases of hemolytic disease of the fetus and newborn (HDFN) have been reported involving anti-Lan and all have been characterized as "mild." CASE REPORT: A 26-year-old Hispanic female presented in her fifth pregnancy for routine obstetric care. Due to progressively rising anti-Lan titers, middle cerebral artery (MCA) Dopplers were performed. At 32 weeks of gestation, the antibody titer had reached 128; the MCA Doppler indicated that fetal anemia was severe. An intrauterine transfusion with Lan antigen-negative RBCs was performed and a viable infant was delivered 25 days later. DISCUSSION: Three cases of HDFN associated with anti-Lan have been previously reported. While these cases have been associated with somewhat variable serologic findings, none have resulted in fetal demise or severe symptomatology requiring pre- or postnatal intervention other than routine phototherapy. The current report, however, suggests that in some instances anti-Lan can result in a more severe form of HDFN requiring more aggressive prenatal therapy. CONCLUSION: In spite of previous case reports suggesting that anti-Lan is associated with relatively mild HDFN, this case suggests that in some instances, this antibody can cause severe HDFN requiring prenatal intervention.

Genetic variation of the HNA-3a encoding gene.

BACKGROUND: Antibodies against the human neutrophil alloantigen-3a (HNA-3a) play an important role in transfusion-related acute lung injury. The HNA-3a and -3b alloantigens result from a single-nucleotide exchange in the choline transporter-like protein 2 gene (CTL2). We sought for additional polymorphisms that might impair antibody binding to or genotyping of the HNA-3a or -3b antigens. STUDY DESIGN AND METHODS: CTL2-specific complementary DNA (cDNA) fragments were generated from 67 unrelated blood donors followed by DNA sequencing. Polymerase chain reaction with sequence-specific primers (PCR-SSP) was used to test a higher number of donors for relevant new single-nucleotide polymorphisms (SNPs). The granulocyte agglutination test recommended for HNA-3a antibody detection was performed to check HNA-3a antibody binding to the products of the CTL-2 gene variants. RESULTS: Two new missense mutations were demonstrated in the CTL2 cDNA: a 537C>T* exchange leading to a Leu153Phe amino acid substitution and 988C>T variation predicting Thr301Met change. The inherited 537T variant is located in HNA-3a allele results impaired granulocyte agglutination by four of 14 antibodies tested while 988T remains nearly unaffected. CONCLUSIONS: The Leu153Phe exchange next to the HNA-3a/b defining amino acid position can impede the binding of HNA-3a alloantibodies. The HNA-3a genotyping by PCR-SSP might produce misleading results in HNA-3ab heterozygous individuals with the additional CTL2-537T variation of the HNA-3a antigen. These findings must account for the development of new screening assays.

Cell therapy to promote transplantation tolerance: a winning strategy?

Organ transplantation is currently the only effective treatment for end-stage organ failure. However, success is limited by the immune response of the recipient to allogeneic tissues (recognized by the direct and indirect alloresponses) and by the morbidity and mortality associated with the immunosuppressive drugs that are used to control alloimmunity. One solution to these problems is the induction of immunological tolerance. In our laboratory, we have selected two strategies to achieve this goal. The first is to expand and/or generate Tregs directly in vivo using infusions of 'tolerogenic' DCs into patients; the second is to purify Tregs from the blood of patients on the waiting list for a transplant, enrich and expand these cells in vitro and then inject back in vivo after transplantation. Here, we have summarized our results both in the murine and human systems on the use of Treg-based strategies to induce tolerance to the transplanted organs.

Manipulating the bioenergetics of alloreactive T cells causes their selective apoptosis and arrests graft-versus-host disease.

Cells generate adenosine triphosphate (ATP) by glycolysis and by oxidative phosphorylation (OXPHOS). Despite the importance of having sufficient ATP available for the energy-dependent processes involved in immune activation, little is known about the metabolic adaptations that occur in vivo to meet the increased demand for ATP in activated and proliferating lymphocytes. We found that bone marrow (BM) cells proliferating after BM transplantation (BMT) increased aerobic glycolysis but not OXPHOS, whereas T cells proliferating in response to alloantigens during graft-versus-host disease (GVHD) increased both aerobic glycolysis and OXPHOS. Metabolomic analysis of alloreactive T cells showed an accumulation of acylcarnitines consistent with changes in fatty acid oxidation. Alloreactive T cells also exhibited a hyperpolarized mitochondrial membrane potential (ΔΨm), increased superoxide production, and decreased amounts of antioxidants, whereas proliferating BM cells did not. Bz-423, a small-molecule inhibitor of the mitochondrial F(1)F(0) adenosine triphosphate synthase (F(1)F(0)-ATPase), selectively increased superoxide and induced the apoptosis of alloreactive T cells, which arrested established GVHD in several BMT models without affecting hematopoietic engraftment or lymphocyte reconstitution. These findings challenge the current paradigm that activated T cells meet their increased demands for ATP through aerobic glycolysis, and identify the possibility that bioenergetic and redox characteristics can be selectively exploited as a therapeutic strategy for immune disorders.

Hemolytic disease of the newborn associated with anti-Jra alloimmunization in a twin pregnancy: the first case report in Korea.

Jr(a) is a high-frequency antigen found in all ethnic groups. However, the clinical significance of the anti-Jr(a) antibody has remained controversial. Most studies have reported mild hemolytic disease of the newborn and fetus (HDNF) in Jr(a)-positive patients. Recently, fatal cases of HDNF have also been reported. We report the first case of HDNF caused by anti-Jr(a) alloimmunization in twins in Korea. A 33-yr-old nulliparous woman with no history of transfusion or amniocentesis was admitted at the 32nd week of gestation because of vaginal bleeding caused by placenta previa. Anti-Jr(a) antibodies were detected in a routine laboratory examination. An emergency cesarean section was performed at the 34th week of gestation, and 2 premature infant twins were delivered. Laboratory examination showed positive direct antiglobulin test and Jr(a+) phenotype in the red blood cells and the presence of anti-Jr(a) antibodies in the serum in both neonates. The infants underwent phototherapy for neonatal jaundice; this was followed by conservative management. They showed no further complications and were discharged on the 19th postpartum day. Preparative management to ensure the availability of Jr(a-) blood, via autologous donation, and close fetal monitoring must be performed even in cases of first pregnancy in Jr(a-) women.

Two different regulatory T cell populations that promote corneal allograft survival.

PURPOSE: To compare and contrast the T regulatory cells (Tregs) induced by anterior chamber (AC) injection of antigen with those induced by orthotopic corneal allografts. METHODS: Anterior chamber-associated immune deviation (ACAID) Tregs were induced by injecting C57BL/6 spleen cells into the AC of BALB/c mice. Delayed-type hypersensitivity responses to C57BL/6 alloantigens were evaluated by a conventional ear swelling assay. Corneal allograft Tregs were induced by applying orthotopic C57BL/6 corneal allografts onto BALB/c hosts. The effects of anti-CD25, anti-CD8, anti-interferon-γ (IFN-γ), anti-IL-17A, or cyclophosphamide treatments on corneal allograft survival and ACAID were evaluated. RESULTS: Administration of either anti-CD25 or anti-IFN-γ antibodies prevented the expression of ACAID and abolished the immune privilege of corneal allografts. By contrast, in vivo treatment with anti-CD8 antibody abrogated ACAID but had no effect on corneal allograft survival. Further discordance between ACAID and corneal allograft survival emerged in experiments in which the induction of allergic conjunctivitis or the administration of anti-IL-17A abolished the immune privilege of corneal allografts but had no effect on the induction or expression of ACAID. CONCLUSIONS: Although orthotopic corneal allografts are strategically located for the induction of ACAID by the sloughing of corneal cells into the AC, the results reported here indicate that the Tregs induced by orthotopic corneal allografts are remarkably different from the Tregs that are induced by AC injection of alloantigen. Although both of these Treg populations promote corneal allograft survival, they display distinctly different phenotypes.

Isatis tinctoria L. combined with co-stimulatory molecules blockade prolongs survival of cardiac allografts in alloantigen-primed mice.

Memory T cells present a unique challenge in transplantation. Although memory T cells express robust immune responses to invading pathogens, they may be resistant to the effects of immunosuppressive therapies used to prolong graft survival. In previous studies, we found that compound K, the synthesized analogue of highly unsaturated fatty acids from Isatis tinctoria L., reduced acute cardiac allograft rejection in mice (Wang et al., 2009 [1]). Here, we further investigated the effect of compound K on cardiac allograft rejection in alloantigen-primed mice. We found that compound K significantly inhibited CD4(+) and CD8(+) memory T cells proliferation in a mixed lymphocyte reaction (MLR). In vivo, compound K combined with anti-CD154 and anti-LFA-1 monoclonal antibodies (mAbs) significantly extended the survival time of heart grafts in alloantigen-primed mice with no obvious toxic side effects. Furthermore, our data suggests that compound K works by reducing the expression of both IL-2 and IFN-gamma within the graft rather than enhancing expression of regulatory T cells (Tregs). Compound K can also inhibit the alloresponses of memory T cells, while increasing the proportion of CD4(+) memory T cells in the spleen of the recipients and significantly reducing the level of alloantibodies in the serum. Our study highlights the unique immune effects of compound K that may be further explored for clinical use in extending the survival of transplant grafts.

Hemolytic Disease of the Newborn Associated with Anti-Jr(a) Alloimmunization in a Twin Pregnancy: The First Case Report in Korea / 대한진단검사의학회지

Jr(a) is a high-frequency antigen found in all ethnic groups. However, the clinical significance of the anti-Jr(a) antibody has remained controversial. Most studies have reported mild hemolytic disease of the newborn and fetus (HDNF) in Jr(a)-positive patients. Recently, fatal cases of HDNF have also been reported. We report the first case of HDNF caused by anti-Jr(a) alloimmunization in twins in Korea. A 33-yr-old nulliparous woman with no history of transfusion or amniocentesis was admitted at the 32nd week of gestation because of vaginal bleeding caused by placenta previa. Anti-Jr(a) antibodies were detected in a routine laboratory examination. An emergency cesarean section was performed at the 34th week of gestation, and 2 premature infant twins were delivered. Laboratory examination showed positive direct antiglobulin test and Jr(a+) phenotype in the red blood cells and the presence of anti-Jr(a) antibodies in the serum in both neonates. The infants underwent phototherapy for neonatal jaundice; this was followed by conservative management. They showed no further complications and were discharged on the 19th postpartum day. Preparative management to ensure the availability of Jr(a-) blood, via autologous donation, and close fetal monitoring must be performed even in cases of first pregnancy in Jr(a-) women.

Immunomodulatory effects of blood transfusions: the synergic role of soluble HLA Class I free heavy-chain molecules detectable in blood components.

BACKGROUND: Over the past decades, the weight of the published literature demonstrates that blood transfusions can induce clinically significant immunosuppression in recipients. Several studies showed significant improved clinical outcomes in the patients receiving leukoreduced transfusions, compared with control patients who received nonleukoreduced transfusions. Moreover, the immunosuppressive potential of blood products grows with the time of their storage and becomes highest in nonleukoreduced blood products stored for a long time. STUDY DESIGN AND METHODS: The interest was previously focused on the determination of immunomodulatory soluble molecules such as soluble HLA Class I (sHLA-I) and soluble Fas ligand (sFasL) in different blood components and on the evaluation of their immunomodulatory activities. On this basis, whether soluble beta2-microglobulin free HLA Class I heavy chains (sHLA-beta2fHC) could be detected and immunochemically characterized in different blood components was evaluated. Immunomodulatory activity of detectable sHLA-beta2fHC molecules was evaluated by apoptosis inducing capacity in interleukin-2-activated antigen-specific cytotoxic T lymphocytes (CTL). RESULTS: Double-determinant immunoenzymatic assay indicates that sHLA-beta2fHC levels in red blood cells stored for up to 30 days and in random-donor platelets are significantly (p < 0.001) higher than in other blood components, and the immunochemical characterization suggests that the major source of sHLA-beta2fHC molecules might be the residual white cells that undergo membrane damage during storage. Finally, allogeneic CD8+ CTL apoptosis induction confirmed biofunctionality of sHLA-beta2fHC molecules. CONCLUSION: These data are comparable with those previously reported dealing with contaminant soluble molecules in allogeneic and autologous blood components, suggesting that sHLA-beta2fHC molecules could contribute to the immunosuppressive effects of blood transfusions.

Blockade of the OX40 ligand prolongs corneal allograft survival.

Although corneal transplantation is one of the most common tissue transplantations and is known to have a high graft acceptance rate, occasional corneal graft rejection remains a cause of blindness. OX40, a member of the TNF receptor superfamily, is expressed on activated T cells, and transmits a costimulatory signal by binding to OX40 ligand (OX40L) expressed on several cells with antigen-presenting functions. Using a blocking monoclonal antibody (mAb) against murine OX40L, we investigated the role of OX40 in a murine model of corneal transplantation. C3H/He mouse corneas were transplanted to BALB/c mice orthotopically. Administration of anti-OX40L mAb significantly reduced allograft rejection, and increased graft survival rate to 40% at 8 weeks after transplantation, while all corneas were rejected within 5 weeks in control IgG-treated mice. Similar reduced rejection was observed when wild-type donor corneas were transplanted to OX40L-deficient recipients. In vitro study revealed that the anti-OX40L mAb treatment reduced proliferative response and IFN-gamma production of draining lymph node cells in response to stimulation with donor alloantigen. These results demonstrate that OX40L blockade is effective for prolongation of corneal allograft survival by inhibiting recipient T cell activation.

The immunosuppressive drug FK778 induces regulatory activity in stimulated human CD4+ CD25- T cells.

The induction of transplantation tolerance involves a T-cell-mediated process of immune regulation. In clinical transplantation, the use of immunosuppressive drugs that promote or facilitate this process would be highly desirable. Here, we investigated the tolerance-promoting potential of the immunosuppressive drug FK778, currently under development for clinical therapy. Using a human allogeneic in vitro model we showed that, upon T-cell receptor (TCR) triggering, FK778 induced a regulatory phenotype in CD4+ CD25- T cells. Purified CD4+ CD25- T cells primed in the presence of FK778 showed hyporesponsiveness upon restimulation with alloantigen in the absence of the drug. This anergic state was reversible by exogenous interleukin-2 (IL-2) and was induced independent of naturally occurring CD4+ CD25+ regulatory T cells. Pyrimidine restriction was a crucial requirement for the de novo induction of regulatory activity by FK778. The FK778-induced anergic cells showed suppressor activity in a cell-cell contact-dependent manner; were CD25(high), CD45RO+, CD27-, and CD62L-; and expressed cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), glucocorticoid-induced tumor necrosis factor receptor (GITR), and FoxP3. The cells revealed delayed p27(kip1) degradation and enhanced phosphorylation of STAT3. In conclusion, the new drug FK778 shows tolerizing potential through the induction of a regulatory T-cell subset in CD4+ CD25- T cells.

Anti-tumor activities of the antlered form of Ganoderma lucidum in allogeneic and syngeneic tumor-bearing mice.

We investigated the anti-tumor effects of a dry powder preparation of the antlered form of Ganoderma lucidum (G. lucidum AF, rokkaku-reishi in Japanese), a variant type of G. lucidum, not only in allogeneic Sarcoma 180-bearing ddY mice, but also in syngeneic MM 46-bearing C3H/He mice. G. lucidum AF inhibited tumor growth and elongated the life span when orally administered to mice by free-feeding of a 2.5% G. lucidum AF-containing diet. It also showed anti-tumor activity in spite of post-feeding after tumor inoculation. G. lucidum AF significantly countered the depression of splenic CD8+ cells and protected the decrease in interferon-gamma (IFN-gamma) production in regional lymph nodes of MM 46-bearing mice, indicating that the anti-tumor activity of G. lucidum AF might be caused by its immunostimulating action. These results suggest that the ingestion of G. lucidum AF can be useful for the prevention and curing of cancer.

Cutting edge: atopy promotes Th2 responses to alloantigens and increases the incidence and tempo of corneal allograft rejection.

A large body of evidence suggests that corneal allograft rejection is mediated by a type 1 Th cell response and that deviation toward type 2 immunity favors graft survival. However, clinical observations indicate that patients with severe ocular allergies have increased risk of corneal allograft rejection. We used a mouse model of atopic conjunctivitis to evaluate the effects of Th2 immune deviation on corneal allograft survival and possible mechanisms of graft rejection. Our results reveal the following novel findings: 1) atopic conjunctivitis promotes systemic Th2 immune responses to corneal graft donor alloantigens; 2) corneal allografts in atopic host eyes have an increased incidence and swifter tempo of rejection; 3) increased rejection is associated with alterations in systemic T cell-mediated responses to donor alloantigens; and 4) corneal allograft rejection in atopic hosts does not require the direct involvement of infiltrating eosinophils.