ABSTRACT
Costimulation blockade (CoB) via belatacept is a lower-morbidity alternative to calcineurin inhibitor (CNI)-based immunosuppression. However, it has higher rates of early acute rejection. These early rejections are mediated in part by memory T cells, which have reduced dependence on the pathway targeted by belatacept and increased adhesion molecule expression. One such molecule is leukocyte function antigen (LFA)-1. LFA-1 exists in two forms: a commonly expressed, low-affinity form and a transient, high-affinity form, expressed only during activation. We have shown that antibodies reactive with LFA-1 regardless of its configuration are effective in eliminating memory T cells but at the cost of impaired protective immunity. Here we test two novel agents, leukotoxin A and AL-579, each of which targets the high-affinity form of LFA-1, to determine whether this more precise targeting prevents belatacept-resistant rejection. Despite evidence of ex vivo and in vivo ligand-specific activity, neither agent when combined with belatacept proved superior to belatacept monotherapy. Leukotoxin A approached a ceiling of toxicity before efficacy, while AL-579 failed to significantly alter the peripheral immune response. These data, and prior studies, suggest that LFA-1 blockade may not be a suitable adjuvant agent for CoB-resistant rejection.
Subject(s)
Abatacept/pharmacology , Graft Rejection/drug therapy , Graft Survival/immunology , Immunologic Memory/immunology , Kidney Transplantation/adverse effects , Lymphocyte Function-Associated Antigen-1/chemistry , T-Lymphocytes/immunology , Animals , Disease Models, Animal , Glomerular Filtration Rate , Graft Rejection/etiology , Graft Rejection/pathology , Graft Survival/drug effects , Immunologic Memory/drug effects , Immunosuppressive Agents/pharmacology , Kidney Function Tests , Lymphocyte Function-Associated Antigen-1/metabolism , Macaca mulatta , Postoperative Complications , T-Lymphocytes/drug effects , T-Lymphocytes/pathologyABSTRACT
Transforming growth factor ß1 (TGFß1) plays a key role in T cell homeostasis and peripheral tolerance. We evaluated the influence of a novel human mutant TGFß1/Fc (human IgG4 Fc) fusion protein on memory CD4+ and CD8+ T cell (Tmem) responses in vitro and their recovery following antithymocyte globulin (ATG)-mediated lymphodepletion in monkeys. TGFß1/Fc induced Smad2/3 protein phosphorylation in rhesus and human peripheral blood mononuclear cells and augmented the suppressive effect of rapamycin on rhesus Tmem proliferation after either alloactivation or anti-CD3/CD28 stimulation. In combination with IL-2, the incidence of CD4+ CD25hi Foxp3hi regulatory T cells (Treg) and Treg:Th17 ratios were increased. In lymphodepleted monkeys, whole blood trough levels of infused TGFß1/Fc were maintained between 2 and 7 µg/mL for 35 days. Following ATG administration, total T cell numbers were reduced markedly. In those given TGFß1/Fc infusion, CD8+ T cell recovery to predepletion levels was delayed compared to controls. Additionally, numbers of CD4+ CD25hi CD127lo Treg increased at 4-6 weeks after depletion but subsequently declined to predepletion levels by 12 weeks. In all monkeys, CD4+ CD25hi Foxp3hi Treg/CD4+ IL-17+ cell ratios were reduced, particularly after stopping TGFß1/Fc infusion. Thus, human TGFß1/Fc infusion may delay Tmem recovery following lymphodepletion in nonhuman primates. Combined (low-dose) IL-2 infusion may be required to improve the Treg:Th17 ratio following lymphodepletion.
Subject(s)
Homeostasis/immunology , Immunologic Memory/immunology , Lymphocyte Depletion/adverse effects , Receptors, Fc/metabolism , T-Lymphocytes, Regulatory/immunology , Transforming Growth Factor beta1/metabolism , Animals , Humans , Leukocytes, Mononuclear/immunology , Macaca mulatta , Male , Receptors, Fc/genetics , Transforming Growth Factor beta1/geneticsABSTRACT
Costimulation blockade with the fusion protein belatacept provides a desirable side effect profile and improvement in renal function compared with calcineurin inhibition in renal transplantation. This comes at the cost of increased rates of early acute rejection. Blockade of the integrin molecule leukocyte function-associated antigen 1 (LFA-1) has been shown to be an effective adjuvant to costimulation blockade in a rigorous nonhuman primate (NHP) model of islet transplantation; therefore, we sought to test this combination in an NHP renal transplant model. Rhesus macaques received belatacept maintenance therapy with or without the addition of LFA-1 blockade, which was achieved using a murine-derived LFA-1-specific antibody TS1/22. Additional experiments were performed using chimeric rhesus IgG1 (TS1/22R1) or IgG4 (TS1/22R4) variants, each engineered to limit antibody clearance. Despite evidence of proper binding to the target molecule and impaired cellular egress from the intravascular space indicative of a therapeutic effect similar to prior islet studies, LFA-1 blockade failed to significantly prolong graft survival. Furthermore, evidence of impaired protective immunity against cytomegalovirus was observed. These data highlight the difficulties in translating treatment regimens between organ models and suggest that the primarily vascularized renal model is more robust with regard to belatacept-resistant rejection than the islet model.
Subject(s)
Abatacept/therapeutic use , Disease Models, Animal , Graft Rejection/prevention & control , Graft Survival/immunology , Kidney Failure, Chronic/immunology , Kidney Transplantation/adverse effects , Lymphocyte Function-Associated Antigen-1/immunology , Animals , Glomerular Filtration Rate , Graft Rejection/etiology , Graft Rejection/pathology , Immunologic Memory , Kidney Failure, Chronic/surgery , Kidney Function Tests , Lymphocyte Function-Associated Antigen-1/administration & dosage , Macaca mulatta , Transplantation, HomologousABSTRACT
In murine models, T-cell costimulation blockade of the CD28:B7 and CD154:CD40 pathways synergistically promotes immune tolerance after transplantation. While CD28 blockade has been successfully translated to the clinic, translation of blockade of the CD154:CD40 pathway has been less successful, in large part due to thromboembolic complications associated with anti-CD154 antibodies. Translation of CD40 blockade has also been slow, in part due to the fact that synergy between CD40 blockade and CD28 blockade had not yet been demonstrated in either primate models or humans. Here we show that a novel, nondepleting CD40 monoclonal antibody, 3A8, can combine with combined CTLA4Ig and sirolimus in a well-established primate bone marrow chimerism-induction model. Prolonged engraftment required the presence of all three agents during maintenance therapy, and resulted in graft acceptance for the duration of immunosuppressive treatment, with rejection resulting upon immunosuppression withdrawal. Flow cytometric analysis revealed that upregulation of CD95 expression on both CD4+ and CD8+ T cells correlated with rejection, suggesting that CD95 may be a robust biomarker of graft loss. These results are the first to demonstrate prolonged chimerism in primates treated with CD28/mTOR blockade and nondepletional CD40 blockade, and support further investigation of combined costimulation blockade targeting the CD28 and CD40 pathways.
Subject(s)
CD40 Antigens/antagonists & inhibitors , Chimerism , Immunoconjugates/immunology , Immunosuppressive Agents/pharmacology , Models, Animal , Sirolimus/pharmacology , Abatacept , Animals , Antibodies, Monoclonal/immunology , CD28 Antigens/immunology , CD40 Antigens/immunology , Flow Cytometry , Hematopoietic Stem Cell Transplantation , Macaca mulattaABSTRACT
The importance of CD40/CD154 costimulatory pathway blockade in immunosuppression strategies is well-documented. Efforts are currently focused on monoclonal antibodies specific for CD40 because of thromboembolic complications associated with monoclonal antibodies directed towards CD154. Here we present the rational development and characterization of a novel antagonistic monoclonal antibody to CD40. Rhesus macaques were treated with the recombinant anti-CD40 mAb, 2C10, or vehicle before immunization with keyhole limpet hemocyanin (KLH). Treatment with 2C10 successfully inhibited T cell-dependent antibody responses to KLH without significant peripheral B cell depletion. Subsequently, MHC-mismatched macaques underwent intraportal allogeneic islet transplantation and received basiliximab and sirolimus with or without 2C10. Islet graft survival was significantly prolonged in recipients receiving 2C10 (graft survival time 304, 296, 265, 163 days) compared to recipients receiving basiliximab and sirolimus alone (graft survival time 8, 8, 10 days). The survival advantage conferred by treatment with 2C10 provides further evidence for the importance of blockade of the CD40/CD154 pathway in preventing alloimmune responses. 2C10 is a particularly attractive candidate for translation given its favorable clinical profile.
Subject(s)
Antibodies, Monoclonal/immunology , CD40 Antigens/immunology , Graft Survival , Islets of Langerhans Transplantation , Animals , Antibody Formation , Humans , Macaca mulattaABSTRACT
Costimulation blockade of the CD40/CD154 pathway has been effective at preventing allograft rejection in numerous transplantation models. This strategy has largely depended on mAbs directed against CD154, limiting the potential for translation due to its association with thromboembolic events. Though targeting CD40 as an alternative to CD154 has been successful at preventing allograft rejection in preclinical models, there have been no reports on the effects of CD40-specific agents in human transplant recipients. This delay in clinical translation may in part be explained by the presence of cellular depletion with many CD40-specific mAbs. As such, the optimal biologic properties of CD40-directed immunotherapy remain to be determined. In this report, we have characterized 3A8, a human CD40-specific mAb and evaluated its efficacy in a rhesus macaque model of islet cell transplantation. Despite partially agonistic properties and the inability to block CD40 binding of soluble CD154 (sCD154) in vitro, 3A8-based therapy markedly prolonged islet allograft survival without depleting B cells. Our results indicate that the allograft-protective effects of CD40-directed costimulation blockade do not require sCD154 blockade, complete antagonism or cellular depletion, and serve to support and guide the continued development of CD40-specific agents for clinical translation.
Subject(s)
Antibodies, Monoclonal/therapeutic use , CD40 Antigens/antagonists & inhibitors , CD40 Ligand/immunology , Graft Survival/immunology , Islets of Langerhans Transplantation , Animals , Antibodies, Monoclonal/immunology , CD40 Antigens/immunology , Flow Cytometry , Immunotherapy , Lymphocyte Culture Test, Mixed , Macaca mulatta , Models, AnimalABSTRACT
Recent findings established that primary targets of HIV/SIV are lymphoid cells within the gastrointestinal (GI) tract. Focus has therefore shifted to T-cells expressing alpha(4)beta(7) integrin which facilitates trafficking to the GI tract via binding to MAdCAM-1. Approaches to better understand the role of alpha(4)beta(7)+ T-cells in HIV/SIV pathogenesis include their depletion or blockade of their synthesis, binding and/or homing capabilities in vivo. Such studies can ideally be conducted in rhesus macaques (RM), the non-human primate model of AIDS. Characterization of alpha(4)beta(7) expression on cell lineages in RM blood and GI tissues reveal low densities of expression by NK cells, B-cells, naïve and TEM (effector memory) T-cells. High densities were observed on TCM (central memory) T-cells. Intravenous administration of a single 50mg/kg dose of recombinant rhesus alpha(4)beta(7) antibody resulted in significant initial decline of alpha(4)beta(7)+ lymphocytes and sustained coating of the alpha(4)beta(7) receptor in both the periphery and GI tissues.
Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/pharmacology , Integrins/immunology , Simian Acquired Immunodeficiency Syndrome/immunology , Simian Immunodeficiency Virus/immunology , Animals , Antibodies, Monoclonal/blood , CD4-Positive T-Lymphocytes/drug effects , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/virology , Cross-Sectional Studies , Flow Cytometry , Gastrointestinal Tract/drug effects , Gastrointestinal Tract/immunology , Gastrointestinal Tract/virology , Integrins/biosynthesis , Longitudinal Studies , Macaca mulatta , Male , Pilot Projects , RNA, Viral/chemistry , RNA, Viral/genetics , Recombinant Proteins/blood , Recombinant Proteins/immunology , Recombinant Proteins/pharmacology , Reverse Transcriptase Polymerase Chain Reaction , Simian Acquired Immunodeficiency Syndrome/blood , Simian Acquired Immunodeficiency Syndrome/virology , Simian Immunodeficiency Virus/genetics , T-Lymphocyte Subsets/drug effects , T-Lymphocyte Subsets/immunology , T-Lymphocyte Subsets/virology , Tretinoin/pharmacology , Viral LoadABSTRACT
Clinical evidence suggests that cellular immunity is involved in controlling human immunodeficiency virus-1 (HIV-1) replication. An animal model of acquired immune deficiency syndrome (AIDS), the simian immunodeficiency virus (SIV)-infected rhesus monkey, was used to show that virus replication is not controlled in monkeys depleted of CD8+ lymphocytes during primary SIV infection. Eliminating CD8+ lymphocytes from monkeys during chronic SIV infection resulted in a rapid and marked increase in viremia that was again suppressed coincident with the reappearance of SIV-specific CD8+ T cells. These results confirm the importance of cell-mediated immunity in controlling HIV-1 infection and support the exploration of vaccination approaches for preventing infection that will elicit these immune responses.
Subject(s)
CD8-Positive T-Lymphocytes/immunology , Simian Acquired Immunodeficiency Syndrome/immunology , Simian Acquired Immunodeficiency Syndrome/virology , Simian Immunodeficiency Virus/immunology , Acquired Immunodeficiency Syndrome/immunology , Acquired Immunodeficiency Syndrome/virology , Animals , Antibodies, Monoclonal/immunology , Antibodies, Viral/blood , Disease Progression , Gene Products, gag/blood , Humans , Lymphocyte Count , Lymphocyte Depletion , Macaca mulatta , Neutralization Tests , RNA, Viral/blood , Simian Immunodeficiency Virus/physiology , T-Lymphocytes, Cytotoxic/immunology , Time Factors , Viral Load , Viremia/immunology , Viremia/virology , Virus ReplicationABSTRACT
In sexual transmission of simian immunodeficiency virus, and early and later stages of human immunodeficiency virus-type 1 (HIV-1) infection, both viruses were found to replicate predominantly in CD4(+) T cells at the portal of entry and in lymphoid tissues. Infection was propagated not only in activated and proliferating T cells but also, surprisingly, in resting T cells. The infected proliferating cells correspond to the short-lived population that produces the bulk of HIV-1. Most of the HIV-1-infected resting T cells persisted after antiretroviral therapy. Latently and chronically infected cells that may be derived from this population pose challenges to eradicating infection and developing an effective vaccine.
Subject(s)
CD4-Positive T-Lymphocytes/virology , HIV Infections/transmission , HIV-1/physiology , Lymphocyte Activation , Simian Acquired Immunodeficiency Syndrome/transmission , Simian Immunodeficiency Virus/physiology , Animals , Anti-HIV Agents/therapeutic use , CD4-Positive T-Lymphocytes/cytology , CD4-Positive T-Lymphocytes/immunology , Cell Cycle , Cervix Uteri/virology , Epithelial Cells/virology , Female , HIV Infections/drug therapy , HIV Infections/virology , Lymph Nodes/virology , Macaca mulatta , RNA, Viral/analysis , Simian Acquired Immunodeficiency Syndrome/virology , Time Factors , Virus ReplicationABSTRACT
Treatment of SIV-infected rhesus macaques with short-term antiretroviral therapy (ART) and partially overlapping infusions of antibody to integrin α4ß7 was reported to induce durable posttreatment viral suppression. In an attempt to replicate those observations, we treated macaques infected with the same virus and with the same ART and monoclonal antibody (mAb) regimens (anti-α4ß7 versus control mAb). Sequencing demonstrated that the virus used was actually SIVmac239-nef-stop, not wild-type SIVmac239. A positive correlation was found at 2 weeks after infection between the frequency of repair of attenuated Nef-STOP virus to pathogenic Nef-OPEN and plasma SIV RNA levels. Levels of plasma viremia before the first antibody infusion and preinfection levels of α4ß7 hi CD4+ T cells, but not treatment with antibody to α4ß7 , correlated with levels of viral replication upon discontinuation of all treatments. Follow-up plasma viremia, peripheral blood CD4+ T cell counts, and lymph node and rectal tissue viral load were not significantly different between anti-α4ß7 and control mAb groups.
Subject(s)
Antibodies, Monoclonal/therapeutic use , HIV Infections/therapy , Integrin alpha4/immunology , Integrin beta Chains/immunology , Simian Acquired Immunodeficiency Syndrome/therapy , Simian Acquired Immunodeficiency Syndrome/virology , Simian Immunodeficiency Virus/genetics , Simian Immunodeficiency Virus/immunology , Animals , Anti-Retroviral Agents/therapeutic use , CD4 Lymphocyte Count , CD4-Positive T-Lymphocytes/immunology , Codon, Terminator , Lymph Nodes/virology , Macaca mulatta , RNA, Viral/blood , Rectum/virology , Simian Acquired Immunodeficiency Syndrome/blood , Simian Acquired Immunodeficiency Syndrome/drug therapy , Simian Immunodeficiency Virus/physiology , Viral Load , Viral Regulatory and Accessory Proteins/genetics , Viral Regulatory and Accessory Proteins/immunology , Viremia/blood , Viremia/immunology , Viremia/therapy , Viremia/virology , Virus ReplicationABSTRACT
The selective delivery in vivo of a T lymphocyte-specific monoclonal antibody and immunotoxin conjugates to T cells in lymph node and spleen was assessed in rhesus monkeys. A transient coating of all T lymphocytes in the lymph nodes and spleens of healthy rhesus monkeys could be achieved after infusion of unconjugated anti-T11. Because derivatized antibody is cleared more rapidly than unconjugated antibody, it was necessary to infuse a higher dose of immunotoxin than antibody alone to achieve saturation of the lymphocyte binding sites with anti-T11. When sufficient antibody-toxin conjugate was infused, toxin was readily demonstrable on lymph node and spleen T cells by 16 h after infusion. This demonstration that toxins can be successfully delivered with specificity to target T cell populations in the monkey suggests that killing of restricted cell populations in vivo should be feasible.
Subject(s)
Antibodies, Monoclonal/administration & dosage , Immunotoxins , Lymph Nodes/cytology , N-Glycosyl Hydrolases , Plant Proteins/administration & dosage , Spleen/cytology , T-Lymphocytes/immunology , Animals , Antibodies, Monoclonal/analysis , Antibodies, Monoclonal/immunology , Antigens/immunology , Antineoplastic Agents, Phytogenic , Disulfides , Histocytochemistry , Macaca mulatta , Plant Proteins/analysis , Ribosome Inactivating Proteins, Type 1 , Saporins , T-Lymphocytes/analysisABSTRACT
The T cell tropic retrovirus of macaque monkeys simian T lymphotropic virus type III (STLV-III) has morphologic, growth, and antigenic properties indicating that it is related to human T cell lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV), the etiologic agent of the acquired immune deficiency syndrome (AIDS) of humans. STLV-III has recently been shown to induce an AIDS-like disease in macaque monkeys. In this study the humoral immune responses of six experimentally infected monkeys have been characterized to determine whether certain parameters of the antibody response to the virus might be predictive of the clinical outcome of this infection. Two distinct patterns of antibody responses were found. Four animals that died within 160 d of inoculation developed low titer anti-STLV-III antibody responses that recognized only the viral envelope protein, and progressive declines in total plasma IgG levels and absolute peripheral blood T4 lymphocyte numbers. The two animals that lived longer (one died at 352 d, the other remains alive at 430 d) developed high titer anti-STLV-III antibody responses that recognized both viral envelope and core proteins, increases in total plasma IgG, and a later decrease in number of peripheral blood T4 lymphocytes. Interestingly, the single animal that has remained clinically healthy after infection was the only one to develop detectable STLV-III neutralizing antibodies.
Subject(s)
Acquired Immunodeficiency Syndrome/immunology , Antibody Formation , Retroviridae/immunology , Acquired Immunodeficiency Syndrome/pathology , Animals , Antibodies, Viral/analysis , Cerebral Cortex/immunology , Cerebral Cortex/pathology , Enzyme-Linked Immunosorbent Assay , Macaca mulatta , Neutralization Tests , Retroviridae/isolation & purificationABSTRACT
Although alterations in T lymphocyte subset distribution and function in the peripheral blood of HIV-infected humans are well defined, the extent to which these reflect changes in other lymphoid compartments is unclear. We have characterized the coincident changes in PBL and lymph nodes (LN)1 after simian immunodeficiency virus of macaques (SIVmac) infection of rhesus monkeys. Whereas no consistent change in CD8+ PBL was noted during the first 60 d after infection, CD8+ lymphocytes increased significantly in number in LN. These CD8+ LN lymphocytes exhibited an increased expression of MHC class II and a decreased expression of leukocyte adhesion molecule-1, suggesting that they were activated, but interestingly did not express CD25 (IL-2 receptor). Moreover, there was no evidence that these CD8+ LN cells were proliferating, suggesting that they had migrated to the LN. These changes in the LN CD8+ lymphocyte population preceded any detectable change in the light microscopic appearance of the LN. When SIVmac-specific effector T cell responses were assessed, the magnitude of virus-specific effector activity was nearly identical in the PBL and LN of each monkey studied. However, the presence of SIVmac-specific effector cells in the LN did not correlate with the presence of CD8+, MHC class II+ cells. These findings suggest that this numerically important CD8+ lymphocyte subpopulation may serve a regulatory function.
Subject(s)
CD8 Antigens/analysis , Lymph Nodes/immunology , Simian Acquired Immunodeficiency Syndrome/immunology , T-Lymphocyte Subsets/immunology , Animals , Antigens, CD/analysis , CD4 Antigens/analysis , Cell Adhesion Molecules/analysis , Histocompatibility Antigens/analysis , Histocompatibility Antigens Class II/analysis , L-Selectin , Leukocyte Common Antigens , Lymph Nodes/pathology , Macaca mulatta , Receptors, Interleukin-2/analysis , Simian Acquired Immunodeficiency Syndrome/pathology , T-Lymphocytes, Cytotoxic/physiologyABSTRACT
The cytotoxic effect of a lymphocyte-specific immunotoxin formed by disulfide conjugation of an anti-T11 monoclonal antibody with the ribosome-inactivating protein gelonin was assessed in vitro on peripheral blood T cells and in vivo on splenic and lymph node T cells of macaque monkeys. This immunotoxin was cytotoxic to proliferating peripheral blood T cells in vitro as measured by both direct and indirect assays. Two sequential intravenous infusions into macaque monkeys achieved plasma concentrations of immunotoxin far in excess of those shown to be cytotoxic for cultured T cells and coated all T cells in lymph nodes and spleen with intact immunotoxin for four days. However, the cytotoxic effect of the immunotoxin on T cells in vivo was considerably less than that predicted by the in vitro studies. Further experiments suggested that the state of activation of the targeted T cell population in vivo, or the appearance of anti-immunotoxin antibodies, which occurred in all infused monkeys, might attenuate immunotoxin-mediated cell killing in vivo. These studies illustrate the significant differences between the action of immunotoxin conjugates in vitro, and those seen when these conjugates are utilized as therapeutic agents in vivo.
Subject(s)
Antibodies, Monoclonal/administration & dosage , Antibody Specificity , Antigens, Differentiation/immunology , Antilymphocyte Serum/administration & dosage , Immunotoxins/administration & dosage , Plant Proteins/toxicity , Receptors, Immunologic/immunology , T-Lymphocytes/immunology , Animals , Antibodies, Anti-Idiotypic/biosynthesis , Antibodies, Monoclonal/toxicity , Antilymphocyte Serum/toxicity , Blood Physiological Phenomena , CD2 Antigens , Cytotoxicity Tests, Immunologic , Cytotoxins/administration & dosage , Cytotoxins/toxicity , Drug Stability , Humans , Immunosuppressive Agents/administration & dosage , Immunosuppressive Agents/toxicity , Immunotoxins/toxicity , Interphase/drug effects , Lymphocyte Activation/drug effects , Macaca fascicularis , Mice , Ribosome Inactivating Proteins, Type 1 , Thymidine/antagonists & inhibitorsABSTRACT
Monoclonal antibodies, either alone or conjugated to toxins, hold promise as important therapeutic agents. However, the immune response to these foreign protein agents may markedly limit their therapeutic utility in vivo. We have administered both an interleukin-2 receptor-specific monoclonal antibody (anti-IL-2R) and a CD2-specific monoclonal antibody linked to the ribosome-inactivating protein gelonin to macaque monkeys. The monkeys developed high-titer antibody responses to mouse Ig and, when immunotoxin was administered, to the toxin gelonin. Their antimouse Ig antibody responses were broadly reactive with mouse Ig of differing idiotypes and isotypes. Furthermore, sera from these monkeys blocked the in vitro cytotoxic effect of anti-IL-2R or immunotoxin. This blocking was mediated by both the antimouse Ig and the antigelonin antibodies. Serum from a monkey infused with one CD2-specific monoclonal antibody blocked the in vitro cytotoxicity of two other isotypically different CD2-specific monoclonal antibody conjugates. In addition, this serum blocked the in vitro cytotoxicity of a gelonin-monoclonal antibody conjugate of an unrelated specificity. These data indicate that the immune response to some monoclonal antibodies and toxins might preclude the later use of this class of substances in an individual. Therefore, strategies for the parental therapeutic use of monoclonal antibodies and immunotoxins must take into consideration the possible limiting effects of the humoral immune response to these agents.
Subject(s)
Antibodies, Monoclonal/immunology , Immunotoxins/immunology , Animals , Antibodies, Anti-Idiotypic/analysis , Antibody Formation , Antibody Specificity , Antigens, Differentiation, T-Lymphocyte/immunology , CD2 Antigens , Immune Sera/immunology , Lymphocyte Activation , Macaca fascicularis , Mice , Plant Proteins/immunology , Receptors, Immunologic/immunology , Receptors, Interleukin-2/immunology , Ribosome Inactivating Proteins, Type 1ABSTRACT
In an effort to produce specific immunosuppression through the targeting of those lymphocytes expressing cell surface interleukin 2 receptors in response to an allograft, the anti-human IL-2 receptor monoclonal antibody anti-Tac was administered to cynomolgus monkeys receiving renal transplants. The data demonstrate that anti-Tac produces a significant delay in renal allograft rejection and prolongs host survival in cynomolgus monkeys. Though higher doses of anti-Tac produce modest delays in rejection, there was a surprising finding of greatly prolonged survival in three of five monkeys treated with much lower doses of anti-Tac. Anti-Tac was not shown to be synergistic with cyclosporine in this model. Animals treated with anti-Tac developed high titers of antibodies against the murine monoclonal antibody after 6-8 days of treatment, associated with the disappearance of plasma anti-Tac staining of activated lymphocytes as measured by flow cytometry. The data confirm the utility of the IL-2 receptor as a target for immunosuppressive therapy, and suggest that investigations of dosage and of methods to reduce the immunogenicity of anti-IL-2 receptor agents may be beneficial.
Subject(s)
Antibodies, Monoclonal/immunology , Kidney Transplantation , Receptors, Interleukin-2/immunology , Animals , Antibodies, Anti-Idiotypic/biosynthesis , Antibodies, Monoclonal/pharmacokinetics , Cyclosporins/administration & dosage , Dose-Response Relationship, Immunologic , Graft Survival , Kidney/pathology , Macaca fascicularis , Time FactorsABSTRACT
Questions regarding the potential impact of complement-activating antibodies on lentivirus pathogenesis and vaccine development were addressed in the SIV/macaque model by evaluating sera for activity related to complement-mediated, antibody-dependent enhancement (C'-ADE) of SIV infection in vitro. C'-ADE activity in sera obtained during acute primary infection in macaques inoculated with SIVmac251 appeared before neutralizing antibodies and coincided with the initial peak and decline of plasma antigenemia. The power of C'-ADE activity (i.e., virus production measured by p24 immunoassay) decreased as titers of neutralizing antibodies increased in these animals, suggesting a balance in the net effect between C'-ADE and neutralizing activities in vitro. Antibodies with C'-ADE activity were also induced in macaques immunized with live-attenuated SIVmac239/nef-deletion or primed with recombinant SIVmne gp120 vaccinia virus and boosted with SIVmne rgp160. The titer (i.e., last serum dilution to show enhancement), peak (i.e., serum dilution producing the greatest enhancement as measured by p24 production), and power (i.e., magnitude of p24 production at the peak titer) of C'-ADE activity in sera obtained from vaccinated macaques on the day of challenge were comparable to those of sera from infected macaques and showed no correlation with vaccine outcome, where some protected animals had C'-ADE profiles that resembled those of unprotected animals. The results of these studies suggest that antibodies having C'-ADE activity in vitro could contribute to virus replication or, alternatively, to virus clearance during the acute stage of SIV infection in macaques.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Antibodies, Viral/immunology , Complement Activation/immunology , Simian Acquired Immunodeficiency Syndrome/immunology , Simian Immunodeficiency Virus/immunology , Animals , Macaca , Recombinant Proteins/genetics , Recombinant Proteins/immunology , Simian Acquired Immunodeficiency Syndrome/prevention & control , Vaccination , Viral Envelope Proteins/genetics , Viral Envelope Proteins/immunology , Viral Vaccines/administration & dosage , Viral Vaccines/immunologyABSTRACT
A definition of the specific cell types that support HIV replication early in the course of infection will be important for understanding AIDS pathogenesis and designing strategies for preventing infection. Observations have indicated that the population of lymphocytes susceptible to productive infection extends beyond activated CD4(+) T cells. To explore this issue, we have employed laser scanning cytometry technology and the techniques of lymphocyte surface immunophenotyping followed by fluorescent in situ hybridization to detect simian immunodeficiency virus of macaques (SIVmac) RNA in phenotypically defined rhesus monkey lymphocytes. The immunophenotype of productively infected cells in either a rhesus monkey T cell line or in PBMCs infected in vitro with SIVmac was remarkably similar to that observed in productively infected PBMCs obtained from monkeys during primary infection. We observed low levels or no detectable expression of CD4 on cells infected in vitro or on PBMCs of infected monkeys. However, a substantial number of SIVmac-infected PBMCs both in cultured lymphocytes and sampled directly from infected monkeys expressed CD8 but not CD4. These observations are consistent with the possibility that the CD4 molecule may be modulated off the surface of CD4(+)CD8(-) or CD4(+)CD8(+) lymphocytes after infection or that infection occurred via a CD4-independent mechanism. Moreover, there was no preferential expression of CD25 on cells positive for SIVmac RNA, which might have been predicted if replication of the virus was occurring selectively in activated lymphocytes. These results broaden the range of lymphocytes that support productive SIVmac infection to include CD4(-)CD8(-) and CD4(-)CD8(+) subsets, and are consistent with virus replication occurring in nonactivated cells.
Subject(s)
CD4-Positive T-Lymphocytes/virology , CD8-Positive T-Lymphocytes/virology , RNA, Viral/blood , Simian Acquired Immunodeficiency Syndrome/virology , Simian Immunodeficiency Virus/isolation & purification , Animals , Cell Line, Transformed , Disease Models, Animal , Flow Cytometry , HIV Infections/immunology , HIV Infections/virology , Humans , Immunophenotyping , In Situ Hybridization, Fluorescence/methods , Macaca mulatta , Simian Acquired Immunodeficiency Syndrome/immunologyABSTRACT
With the demonstration that interleukin 12 can enhance natural killer (NK) cell activity and drive CD4+ lymphocytes toward T helper type 1 (Thl) responses, there is a strong rationale for exploring the use of this cytokine as an immunomodulatory therapy in HIV-1-infected individuals. To assess its potential safety and effects on both immune and virologic aspects of HIV-1 infection, recombinant human IL-12 (rhIL-12) was assessed in rhesus monkeys chronically infected with the simian immunodeficiency virus of macaques (SIVmac). The activity of rhIL-12 on rhesus monkey lymphocytes was confirmed with the demonstration that peripheral blood lymphocyte lysis of the NK-sensitive cell line Colo was enhanced by this recombinant cytokine. Further, rhIL-12 was shown to induce interferon-gamma production by rhesus monkey lymphocytes in vitro. Then, in separate studies, two treatment regimens of rhIL-12 were assessed in SIVmac-infected monkeys: a low-dose regimen (0.1 microg/kg, daily for 4 weeks) and a high-dose regimen (2.5 microg/kg, every 3-4 days, for 3 weeks). Both rhIL-12 treatment regimens were well tolerated by these virus-infected animals. The high-dose regimen of rhIL-12 induced transient decreases in circulating lymphocytes in the SIVmac-infected monkeys. Furthermore, no changes in lymphocyte-associated SIVmac DNA or SIVmac plasma RNA levels were seen in the treated monkeys. These studies indicate that short-term treatment with rhIL-12 is well tolerated and causes no measurable changes in virus load in chronically SIVmac-infected rhesus monkeys.