T cell costimulation, checkpoint inhibitors and anti-tumor therapy

The hallmarks of the adaptive immune response are specificity and memory. The cellular response is mediatedby T cells which express cell surface T cell receptors (TCRs) that recognize peptide antigens in complex withmajor histocompatibility complex (MHC) molecules on antigen presenting cells (APCs). However, binding ofcognate TCRs with MHC-peptide complexes alone (signal 1) does not trigger optimal T cell activation. Inaddition to signal 1, the binding of positive and negative costimulatory receptors to their ligands modulates Tcell activation. This complex signaling network prevents aberrant activation of T cells. CD28 is the mainpositive costimulatory receptor on naı¨ve T cells; upon activation, CTLA4 is induced but reduces T cellactivation. Further studies led to the identification of additional negative costimulatory receptors known ascheckpoints, e.g. PD1. This review chronicles the basic studies in T cell costimulation that led to the discoveryof checkpoint inhibitors, i.e. antibodies to negative costimulatory receptors (e.g. CTLA4 and PD1) whichreduce tumor growth. This discovery has been recognized with the award of the 2018 Nobel prize in Physiology/Medicine. This review highlights the structural and functional roles of costimulatory receptors, themechanisms by which checkpoint inhibitors work, the challenges encountered and future prospects.

Inmunoterapia en cáncer: Perspectivas actuales, desafíos y nuevos horizontes / Immunotherapy in cancer. Current prospects, challenges and new horizons

La activación del sistema inmunológico en pacientes con cáncer ha sido un objetivo histórico en el campo de la oncología. En las últimas décadas, nuestro entendimiento de la respuesta inmunológica antitumoral ha promovido el desarrollo de novedosas estrategias terapéuticas dando como resultado un cambio de paradigma en el tratamiento del cáncer. La utilización de agentes bloqueantes de puntos de chequeo del sistema inmunológico como PD-1/PD-L1 y CTLA-4, de agonistas de moléculas co-estimuladoras como CD137 y OX-40 y la transferencia adoptiva de células T antitumorales modificadas genéticamente han generado importantes beneficios clínicos, reflejados en respuestas objetivas y durader as, en enfermos sin tratamientos convencionales disponibles. Sin embargo, un gran número de pacientes no responde a dichas terapias generando resistencia o sufriendo recaídas de la enfermedad debido a la aparición de circuitos inhibitorios o compensatorios. La combinación racional de estrategias terapéuticas permite eliminar mecanismos de resistencia, mientras que la identificación de biomarcadores predictivos facilita la selección de pacientes respondedores a dichos tratamientos. Recientes ensayos clínicos y estudios pre-clínicos permiten vislumbrar un escenario optimista con importantes desafíos en la implementación de estrategias de inmunoterapia en cáncer.

Recent under-standing of the mechanisms that control immune system homeostasis and orchestrate antitumor responses has prompted the development of novel immunotherapeutic modalities. These include antibodies that target immune checkpoints such as PD-1/PD-L1 and CTLA-4, agonistic antibodies of costimulatory molecules such as CD137 and OX-40 and the adoptive transfer of genetically-modified antitumor T cells. However, a large number of patients do not respond to these therapies and develop resistance as a result of activation of compensatory circuits. Rational combination of immunotherapeutic modalities will help overcome resistance and will increase the number of patients who will benefit from these treatments. Moreover, identification of predictive biomarkers will allow selection of patients responding to these treatments. Emerging clinical trials and pre-clinical studies have shown exciting results anticipating new horizons in the design and implementation of cancer immunotherapeutic modalities.

Purification of monoclonal anti-B7-H4 antibody and the blockade of B7-H4-mediated tumor immune evasion by the antibody / 中国药科大学学报

The purified 3C8 was obtained by two step column purification,including Protein G affinity purification and DEAE anion exchange purification.The purity of purified 3C8 was about 93％ when analyzed by reverse column.SDS-PAGE showed that the purity of 3C8 was increased greatly by two step purification.By flowcytometry we found that 3C8 specifically binded with B7-H4/293T cells and did not bind with Mock/293T cells,moreover 3C8 did not bind with other B7 family members transgene cells.In confocal experiment 3C8 could specifically stained B7-H4/293T cells.In Western blot only B7-H4/293T cells showed positive band while Mock/293T cells showed negative result.The result of immunohistochemistry showed that B7-H4 was highly expressed in prostate cancer and renal cell carcinoma,while para-cancer tissues did not express B7-H4.The T cell proliferation experiment showed that B7-H4-Ig could bind to activate T cells and inhibit T cell proliferation,while 3C8 could block the binding of B7-H4-Ig and reverse the T cell proliferation inhibition effect of B7-H4-Ig by CFSE and CCK8 assay.The cytokine IFN-γ and IL-2 secreted by activating T cells was decreased by B7-H4-Ig and 3C8 could reverse the effect of B7-H4-Ig.

Experimental study on effect of immune response mediated by ICOS signal in renal fibrosis of SHR / 中国免疫学杂志

Objective:To preliminarily study the immune response mediated by inducible costimulation molecule in the role of essential hypertensive renal damage .Methods: The blood pressure of spontaneously hypertensive rats and the wild control group (Wistar-Kyoto rats)was dynamically monitored by noninvasive tail artery blood pressure measuring instrument .The urine protein of the rats in 24 hours was dynamically detected by ELISA .The levels of ICOS protein and its mRNA in the rat′s kidneys were dynamically detected by immunohistochemistry , RT-PCR, respectively.The levels of IL-17A and TGF-β1 in the rat′s plasma and kidneys were dynamically detected by ELISA ,immunohistochemistry ,respectively.The renal pathological changes of the rats were detected by HE and MASSON staining.Results:The blood pressure and urine protein in 24 h of SHRs were significantly higher than that of group WKY from 6 weeks.The expression of ICOS protein and its mRNA in SHRs were significantly higher than that of WKY rats from 6 weeks,and there are significantly positive correlations between the dynamic change of ICOS protein and its mRNA and renal fibrosis score of SHRs (rA=0.813,PA<0.05;rB=0.753,PB<0.05).The expression of IL-17A and TGF-β1 in SHR′s plasma and kidneys were significantly higher than that of WKY rats at the weeks 10 and 23.HE and Masson staining showed that the degree of renal fibrosis of SHRs was sig-nificantly higher than that of WKY rats at 23 weeks.Conclusion:The immune response mediated by ICOS plays an important role in hypertensive renal damage .

Effects of lupeol on human co-stimulation cells and colonic cancer cell lines SW480 / 医学研究生学报

Objective Co-stimulation cells is a kind of natual killer (NK)-like T cells, which can kill tumor cells.Previous studies show that lupeol , an natural plant extracts , can change the growth of NK cells ,γδT cells and their effects on tumor cells .This study aimed to investigate the effects of lupeol on human co-stimulation cells and colonic cancer cell lines SW 480 . Methods The peripheral blood mononuclear cells ( PBMC) from healthy volunteers were induced in vitro by different cytokines and transferred into Co-simulation cells.After SW480 and Co-stimulation cells were incubated with different concentrations of lupeol for different durations , methyl thiazolyl tetrazolium (MTT) was used to detect the effects of lupeol on co-stimulation cells and colonic cancer cell lines SW480. Lactate dehydrogenase was used to determine the cell-killing activity of Co-simulation cells to colonic cancer lines SW 480 . Results The concentration of lupeol in 0.1-200.0 mg/L promoted the growth of Co-stimulation cells and inhibited the colonic cancer cell lines SW480.When the concentration of lupeol is at 12.5 mg/L, the cell-killing activity of Co-simulation cells to colonic cancer lines SW 480 was enhanced significantly compared with the controls (76%vs 40%, P<0.05). Conclusion Lupeol could promote the prolifera-tion of Co-stimulation cells, inhibit the growth of cancer lines SW480, and strengthen the cytotoxicity of Co-stimulation cells against co-lonic cell lines SW480.

The CD28-B7 Family in Anti-Tumor Immunity: Emerging Concepts in Cancer Immunotherapy

The interactions between B7 molecules and CD28-family receptors are crucial in the regulation of adaptive cellular immunity. In cancer, the aberrant expression of co-inhibitory B7 molecules has been attributed to reduced anti-tumor immunity and cancer immune evasion, prompting the development of cancer therapeutics that can restore T cell function. Murine tumor models have provided significant support for the targeting of multiple immune checkpoints involving CTLA-4, PD-1, ICOS, B7-H3 and B7-H4 during tumor growth, and clinical studies investigating the therapeutic effects of CTLA-4 and PD-1 blockade have shown exceptionally promising results in patients with advanced melanoma and other cancers. The expression pattern of co-inhibitory B7 ligands in the tumor microenvironment has also been largely correlated with poor patient prognosis, and recent evidence suggests that the presence of several B7 molecules may predict the responsiveness of immunotherapies that rely on pre-existing tumor-associated immune responses. While monotherapies blocking T cell co-inhibition have beneficial effects in reducing tumor burden, combinatorial immunotherapy targeting multiple immune checkpoints involved in various stages of the anti-tumor response has led to the most substantial impact on tumor reduction. In this review, we will examine the contributions of B7- and CD28-family members in the context of cancer development, and discuss the implications of current human findings in cancer immunotherapy.

Integration of the Innate and Adaptive Immunity by CD137-CD137L Bidirectional Signals: Implications in Allograft Rejection / 대한이식학회지

Two-signal models are useful in explaining various types of immune responses. In particular, secondary, so-called costimulatory, signals are critically required for the process of T-cell activation, survival, differentiation, and memory formation. Early studies in rodent models showed that targeting T-cell costimulatory pathways elicits immunological tolerance, providing a basis for development of costimulatory therapeutics in allograft rejection. However, as the classic definition of T-cell costimulation continues to evolve, simple blockade of costimulatory pathways has limitations in prevention of allograft rejection. Furthermore, functions of costimulatory molecules are much more diverse than initially anticipated and beyond T cells. In this mini-review, we will discuss CD137-CD137L bidirectional signals as examples showing that two-signals can be applicable to multiple phases of immune responses.

La molécula CD28 y su función en la activación de células T

La molécula CD28 es considerada uno de los receptores coestimuladores más importantes en las células T, necesaria para la completa activación celular. En los últimos años se ha acumulado suficiente evidencia sobre su participación en los mecanismos conocidos como señal 2 de activación celular o coestimuladora. De esta forma se convierte en un blanco atractivo para estrategias terapéuticas en enfermedades autoinmunes y trasplante de órganos. Esta revisión se concentra en los principales mecanismos por los cuales esta molécula participa en la completa activación de las células T

CD28 is a very important correceptor among T cells and provide positive signals that promote and sustain T-cell responses. In the last few years, CD 28 has become an interesting target in grafts and autoimmune diseases. This review will focus on the mechanisms whereby CD28 allowing a complete T cell activation

OX40 stimulation down-regulates the expression of Foxp3 in CD4+ CD25+ regulatory T cells / 中华器官移植杂志

Objective To evaluate the regulatory effect of OX40 co-stimulatory signal on the expression of Foxp3 in inductive regulatory T cells (iTreg) in vitro.Method CD4+ CD25+ naive T cells were isolated from C57BL/6 mouse lymphocyte suspension by MASC CD4+ CD25+ regulatory T cell isolation kit.Inductive Tregs were generated by stimulation of naive T cells in the presence of transforming growth factor beta (TGFβ1),anti-CD3,anti-CD28 and IL-2.The regulatory effect on iTregs was shown by use of OX40 stimulation monoclonal antibody (OX86) or control antibody.Using flow cytometric analysis (FACS),we examined the antibody-based identification of Tregs surface markers CD4 and CD25,along with the intracellular activation marker FoxP3.Results The ratio of CD4+ CD25+ nTregs isolated from mouse lymphatic node was (5.0 ± 0.4)％ vs.(71.8 ± 13.4)％ of TGFβ1-driven iTregs.The ratio of CD4+ CD25+ Tregs was (80.0 ± 1.6) ％ in OX40 stimulation McAb group vs.(86.0 ± 1.4)％ in control antibody group.Furthermore,the expression of Foxp3 was (59.2 ± 0.7) ％ in OX40 stimulation McAb group vs.(70.0 ± 0.8) ％ in control antibody group (P＜0.05).Conclusion TGFβ1-dependent protocol may induce the conversion of naive CD4+ T cells into CD25+ Foxp3+ iTregs.OX40 stimulation can down-regulate the expression of Foxp3 in CD4+ CD25 + iTreg significantly.Thus OX40 molecular may become an attractive target in Tregs-induced transplant tolerance.Further study should be performed to increase the suppressive activity of iTregs through blockade of OX40 signal.

Emerging Co-signaling Networks in T Cell Immune Regulation

Co-signaling molecules are surface glycoproteins that positively or negatively regulate the T cell response to antigen. Co-signaling ligands and receptors crosstalk between the surfaces of antigen-presenting cells (APCs) and T cells, and modulate the ultimate magnitude and quality of T cell receptor (TCR) signaling. In the past 10 years, the field of co-signaling research has been advanced by the understanding of underlying mechanisms of the immune modulation led by newly identified co-signaling molecules and the successful preclinical and clinical trials targeting co-inhibitory molecules called immune checkpoints in the treatment of autoimmune diseases and cancers. In this review, we briefly describe the characteristics of well-known B7 co-signaling family members regarding the expression, functions and therapeutic implications and to introduce newly identified B7 members such as B7-H5, B7-H6, and B7-H7.

Functional Characteristics of C-terminal Lysine to Cysteine Mutant Form of CTLA-4Ig

CTLA-4Ig is regarded as an inhibitory agent of the T cell proliferation via blocking the costimulatory signal which is essential for full T cell activation. To improve applicability, we developed the CTLA-4Ig-CTKC in which the c-terminal lysine had been replaced by cysteine through single amino acid change. The single amino acid mutation of c-terminus of CTLA-4Ig was performed by PCR and was checked by in vitro transcription and translation. DNA construct of mutant form was transfected to Chinese hamster ovary (CHO) cells by electroporation. The purified proteins were confirmed by Western blot and B7-1 binding assay for their binding ability. The suppressive capacity of CTLA-4Ig-CTKC was evaluated by the mixed lymphocyte reaction (MLR) and in the allogeneic pancreatic islet transplantation model. CTLA-4Ig-CTKC maintained binding ability to B7-1 molecule and effectively inhibits T cell proliferation in MLR. In the murine allogeneic pancreatic islet transplantation, short-term treatment of CTLA-4Ig-CTKC prolonged the graft survival over 100 days. CTLA-4Ig-CTKC effectively inhibits immune response both in MLR and in allogeneic islet transplantation model, indicating that single amino acid mutation does not affect the inhibitory function of CTLA-4Ig. CTLA-4Ig-CTKC can be used in vehicle-mediated drug delivery system such as liposome conjugation.

Anti-CD137 mAb Deletes Both Donor CD4+ and CD8+ T Cells in Acute Graft-versus-host Disease

We previously demonstrated that in vivo engagement of CD137, a member of TNF receptor superfamily, can delete allorective CD4+ T cells through the induction of activation-induced cell death (AICD) in chronic graft-versus-host disease (cGVHD) and subsequently reverse established cGVHD. In this study, we further showed that agonistic anti-CD137 mAb was highly effective in triggering AICD of donor CD8+ T cells as well as donor CD4+ T cells in the C57BL/6-->unirradiated (C57BL/6 x DBA/2)F1 acute GVHD model. Our results suggest that strong allostimulation should facilitate AICD of both alloreactive CD4+ and CD8+ T cells induced by CD137 stimulation. Therefore, depletion of pathogenic T cells using agonistic anti-CD137 mAb combined with potent TCR stimulation may be used to block autoimmune or inflammatory diseases mediated by T cells.

Adenosin deaminasa como molécula coestimuladora y marcador de inmunidad celular / Adenosine deaminase as costimulatory molecule and marker of cellular immunity

La adenosin deaminasa (ADA), es una enzima del metabolismo de las purinas que ha sido objeto de mucho interés debido a que el defecto congénito de esta enzima causa el síndrome de inmunodeficiencia combinada severa. Una de las tres isoformas de la enzima (ecto-ADA) es capaz de unirse a la glicoproteína CD26 y a los receptores de adenosina A1 y A2B. La interacción ADA-CD26 produce una señal coestimuladora en los eventos de activación de las células T y en la secreción de IFN-g, TNF-a e IL-6. Durante dicha activación la actividad de la enzima está regulada de manera positiva por IL-2 e IL-12 y negativamente por IL-4, basado en un mecanismo de translocación. Diversos estudios señalan que los niveles séricos y plasmáticos de ADA se elevan en algunas enfermedades causadas por microorganismos que infectan principalmente a los macrófagos; así como en trastornos hipertensivos, lo cual podría representar un mecanismo compensatorio como consecuencia de la elevación de los niveles de adenosina y la liberación de mediadores hormonales e inflamatorios estimulados por la hipoxia.

Adenosine deaminase (ADA) is an enzyme of purine metabolism which has been the subject of much interest because the congenital defect of this enzyme causes severe combined immunodeficiency syndrome. One of the three isoforms of the enzyme (ecto-ADA) is capable of binding to the glycoprotein CD26 and adenosine receptors A1 and A2B. ADA-CD26 interaction produces a costimulatory signal in the events of T cell activation and secretion of IFN-g, TNF-a and IL-6. During this activation, the enzyme activity is regulated positively by IL-2 and IL-12 and negatively by IL-4, based on the mechanism of translocation. Diverse studies suggest that seric and plasmatic levels of ADA rise in some diseases caused by microorganisms infecting mainly the macrophages and in hypertensive disorders, which may represent a compensatory mechanism resulting from increased adenosine levels and the release of hormones and inflammatory mediators estimulated by hipoxia.

Expression and Function of TLR2 on CD4 Versus CD8 T Cells

BACKGROUND: Toll-like receptors (TLRs) play a fundamental role in innate immunity through their capacity to recognize pathogen-associated molecular patterns. Also, TLRs that are expressed in T cells are reported to function as co-stimulatory receptors. However, the functional capacity of TLRs on CD4 T and CD8 T cells has not been directly compared. Here we compared CD4 and CD8 T cell responses to TLR2 ligand plus TCR-mediated stimulation. METHODS: TLR2 expression was analyzed on T cell subsets under naive and alloantigen-primed conditions. We analyzed the effects of TLR2 co-stimulation on proliferation and survival of T cell subsets in vitro when stimulated with soluble anti-CD3 in the presence or absence of synthetic ligand Pam3CSK4. RESULTS: TLR2 expression on CD8 T cells was induced following activation; this expression was much higher than on CD4 T cells. Thus, the molecule was constitutively expressed on Listeria-specific memory CD8 T cells. Based on these expression levels, proliferation and survival were markedly elevated in CD8 T cells in response to the TLR2 co-stimulation by Pam3CSK4 compared with those in CD4 T cells. CONCLUSION: Our data show that TLR2 co-stimulation is more responsible for proliferation and survival of CD8 T cells than for that of CD4 T cells.

The Differential Effects of Donor-Strain Immature Dendritic Cell Subtypes and the Blockade of CD40/CD154 Pathway on the Creation of Allograft Tolerance / 대한신장학회잡지

BACKGOUND: Dendritic cells (DC) are pivotal antigen presenting cells and serve a unique role in initiating immunity. To test the hypothesis that pre-immunization of recipient with certain DC subsets of donor origin can influence graft outcome. METHODS: We have studied the effects of immunization with allogeneic CD4+CD11c+(MDC) and CD8+CD11c+(LDC) DCs on the allograft response. RESULTS: Both immature MDC and LDC subsets from DBA/2 were able to prime naive allogeneic C57BL/6 (B6) T cells in MLR. In vitro allogeneic T cell responses were attenuated by the addition of anti-CD154 mAb into the culture. T cells from B6 mice that received DBA/2 MDC intravenously 4 weeks before testing mounted weaker MLR driven cell proliferation than T cells from LDC pretreated B6 mice. Consistent with the MLR results, combined pretreatment with MDC, but not LDC, plus anti-CD154 mAb produced donor-strain specific long-term graft survival and induced tolerance while treatment with LDC plus anti-CD154 mAb created minimal prolongation of allograft survival in a pancreas islet transplant model (DBA/2->B6). The beneficial effects exerted by MDC and anti-CD154 mAb pretreatment were correlated with TH1 to TH2 immune deviation and with the amplified donor-specific suppressive capacity by recipient CD4+CD25+T cells. CONCLUSION: These findings highlight the capacity of MDC to modulate alloimmune responses, and suggest therapeutic approaches for the induction of donor specific tolerance.

Role of T lymphocyte in the pathogenesis of rheumatoid arthritis / 한양의대학술지

PURPOSE OF REVIEW: Rheumatoid arthritis (RA) is characterized by a chronic T-cell response that has escaped normal control mechanisms. This review summarizes recent insights in pathways that are functional in RA and that favor continuous and pathogenic T-cell activation. RECENT FINDINGS: T-cell activation is ultimately determined by positive signals from costimulatory molecules and negative signals from regulatory T cells. Blockade of the classic costimulatory pathway, CD28-CD80 or CD86, is beneficial in RA. Additional pathways that predominantly control the activation of memory and effector T cells are functionally important in synovial inflammation. Some of these costimulatory molecules(such as stimulatory killer cell immunoglobulin-like receptors and NKG2D) appear to be relatively specific for RA and not to play a role in normal immune responses. In addition to this predominance of positive signals, age-disproportionate decline in thymic activity in RA may lead to a diminution of regulatory T cells and loss of their negative signals. SUMMARY: The successful treatment trial of RA with CTLA-4Ig clearly documents the importance of T-cell costimulation in RA disease activity. Novel costimulatory pathways may be of even greater significance than CD28 in RA and may represent promising new therapeutic targets. The finding of reduced thymic activity in RA is exciting and will stimulate further studies of T-cell homeostasis and the function of regulatory cells.

Immunotherapeutic Effects of CTLA4Ig Fusion Protein on Murine EAE and GVHD

BACKGROUND: CTLA4 (CD152), which is expressed on the surface of T cells following activation, has a much higher affinity for B7 molecules comparing to CD28, and is a negative regulator of T cell activation. In contrast to stimulating and agonistic capabilities of monoclonal antibodies specific to CTLA-4, CTLA4Ig fusion protein appears to act as CD28 antagonist and inhibits in vitro and in vivo T cell priming in variety of immunological conditions. We've set out to confirm whether inhibition of the CD28-B7 costimulatory response using a soluble form of human CTLA4Ig fusion protein would lead to persistent inhibition of alloreactive T cell activation. METHODS: We have used CHO-dhfr cell-line to produce CTLA4Ig fusion protein. After serum free culture of transfected cell line we purified this recombinant molecule by using protein A column. To confirm characterization of fusion protein, we carried out a series of Western blot, SDS-PAGE and silver staining analyses. We have also investigated the efficacy of CTLA4Ig in vitro such as mixed lymphocyte reaction (MLR) & cytotoxic T lymphocyte (CTL) response and in vivo such as experimental autoimmune encephalomyelitis (EAE), graft versus host disease (GVHD) and skin-graft whether this fusion protein could inhibit alloreactive T cell activation and lead to immunosuppression of activated T cell. RESULTS: In vitro assay, CTLA4Ig fusion protein inhibited immune response in T cell-specific manner: 1) Human CTLA4Ig inhibited allogeneic stimulation in murine MLR; 2) CTLA4Ig prevented the specific killing activity of CTL. In vivo assay, human CTLA4Ig revealed the capacities to induce alloantigen-specific hyporesponsiveness in mouse model: 1) GVHD was efficiently blocked by dose-dependent manner; 2) Clinical score of EAE was significantly decreased compared to nomal control; 3) The time of skin-graft rejection was not different between CTLA4Ig treated and control group. CONCLUSION: Human CTLA4Ig suppress the T cell-mediated immune response and efficiently inhibit the EAE, GVHD in mouse model. The mechanism of T cell suppression by human CTLA4Ig fusion protein may be originated from the suppression of activity of cytotoxic T cell. Human CTLA4Ig could not suppress the rejection in mouse skin-graft, this finding suggests that other mechanism except the suppression of cytotoxic T cell may exist on the suppression of graft rejection.

Inhibitory effects of CTLA4-Ig fusion protein on the proliferation of T cell and the antibody production of B cell / 천식및알레르기

BACKGROUND: Atopic asthma is characterized by activation of Th2-type T cells in the bronchial mucosa. Several reports have suggested an important role for costimulation through the CD28/CTLA4 (cytotoxic T lymphocyte-associated antigen 4)-B7 (CD80/CD86) pathway in allergen activation of T cells in animal models of allergen-induced asthma, because B7-CD28/ CTLA4 interaction can promote the differentiation and development of the Th2 lymphocyte subset. OBJECTIVE: In the present study, we intended to investigate a potential role of humanized CTLA4-Ig on the inhibition of T and B cell activation by blocking B7/CD28 interactions. METHOD: For this purpose we produced humanized CTLA4-Ig fusion protein by transfection to CHO cell and examined its inhibitory effects for activated T and B cell responses. We evaluated the inhibitory effect of MLR (mixed lymphocyte reaction) and con A-stimulated T cell proliferation. And we assayed wheather B cell was inhibited by stimulation of costimulatory signal in LPS-induced B cell response and PFC assay. RESULT: In vitro assay, humanized CTLA4-Ig fusion protein inhibited T cell-specific immune response in dose-dependent manner: CTLA4-Ig inhibited allogeneic stimulation in murine MLR, and the proliferation of T cell by the stimulation of Con A. But CTLA4-Ig did not inhibit directly the proliferative response of B cell by the stimulation of LPS. In addition, in vivo assay, CTLA4-Ig inhibited the production of antibody from B cell, which was presented by plaque-forming cell (PFC) assay. CONCLUSION: These findings suggest that humanized CTLA4-Ig is effective to inhibit the proliferation of activated T cell directly by blocking B7/CD28 costimulation. And humanized CTLA4-Ig influences antibody-producing capacity of B cell indirectly by regulating T cell.

ADVANCES IN RESEARCH OF TRANSPLANTATION TROLERACE / 解放军医学杂志

Recent advances in transplantation tolerance were comprehensively reviewed. The contents included the mechanisms and methods of induction and maintenance of transplantation tolerance. Some experimental protocols were introduced including mixed chimerism of allogeneic bone marrow, blockade of co-stimulation signal and transgene technology for transplantation tolerance induction. The problems and the future of clinical transplantation tolerance were objectively evaluated here.

Effects of CD86 costimulation on the modulation of Th2 bias at maternal-fetal interface and the relationship with outcomes of gestation / 中国免疫学杂志

Objective:To explore the role of CD86 costimulation in inducing Th2 bias at maternal-fetal interface and the relationship to outcomes of gestation.Methods:Pregnant DBA/2J mated CBA/J mice with a high embryo resorption rate from 20% to 30% and BALB/C mated CBA/J mice with low embryo resorption rates were studied,with rat anti-murine CD86 mAb administered intraperitoneally at the dosage of 100 ?g,at the time of implantation(day 4) and on the following days(6,8,10) of gestation.The competitive semiquantity RT-PCR and ELISA was applied to analysis of the transcription and expression of Th type-1/Th type-2 cytokines at the maternal-fetal interface at day 9 or day 14 of gestation respectively.The embryo resorption rate was counted at day 14 of gestation.Results:In the model of normal pregnancy,blockade of CD86 costimulation had no significant effects on the original Th2 bias at the maternal-fetal interface,and the outcomes of gestation had not changed significantly.While in the model of abortion-prone,blockade of CD86 costimulation successfully induced a Th2 bias at maternal-fetal interface.Therefore,the embryo resorbing rates decreased significantly.Conclusion:Blocking the CD86 costimulation at the early stage of the abortion-prone pregnancy could recover the physiological balance of Th1/Th2 at maternal-fetal interface and induce the maternal-fetal immune tolerance.