Apoptosis Inhibitor 5: A Multifaceted Regulator of Cell Fate

Apoptosis, or programmed cell death, is a fundamental process that maintains tissue homeostasis, eliminates damaged or infected cells, and plays a crucial role in various biological phenomena. The deregulation of apoptosis is involved in many human diseases, including cancer. One of the emerging players in the intricate regulatory network of apoptosis is apoptosis inhibitor 5 (API5), also called AAC-11 (anti-apoptosis clone 11) or FIF (fibroblast growth factor-2 interacting factor). While it may not have yet the same level of notoriety as some other cancer-associated proteins, API5 has garnered increasing attention in the cancer field in recent years, as elevated API5 levels are often associated with aggressive tumor behavior, resistance to therapy, and poor patient prognosis. This review aims to shed light on the multifaceted functions and regulatory mechanisms of API5 in cell fate decisions as well as its interest as therapeutic target in cancer.

Abstract 464: AAC-11 survival pathways as therapeutic target in cancer: AAC-11 leucine-zipper domain derived peptides exert potent antitumor effects and exhibit favorable stability, pharmacokinetic and toxicology profiles

Background: Due to their basal stress phenotype associated to transformation, cancer cells are addicted to non-mutated, non-oncogenic proteins that do not bear such vital functions in normal cells, a phenomenon referred as Non-Oncogenic Addiction (NOA). Targeting these NOAs could therefore induce selective killing of cancer cells, opening several therapeutic opportunities. Recent data suggest that the stress-related scaffold protein AAC-11 (anti-apoptosis clone 11, also known as Api5) is critically involved in cancer cells resistance to chemotherapies, metastatic potential and escape from the immune system.

Methods: We have developed inactivating peptides based on the fusion of a cell penetrating sequence and portions of the leucine-zipper domain of AAC-11, which functions as a protein-protein interaction module. These peptides induce cancer cells death, through the inhibition of protein-protein interactions between AAC-11 and its partners, while sparing normal cells. We now describe further characterization of our lead peptide, JRT39, which contains residues 377 to 379 of AAC-11 linked to the cell-penetrating peptide “penetratin”.

Results: In vitro, JRT39 causes cell death in a wide spectrum of cancer cell lines with IC50 ranging from 5 µM to 30 µM depending on tumor cell type. In particular, JRT39 showed selective efficacy towards primary cells from Acute Myeloid Leukemia (AML), Acute Lymphocytic Leukemia (ALL) or Sézary syndrome (SS) patients, while sparing normal hematopoietic cells, with an IC50 of 5-15 µM. Mechanistically, JRT39 induces membranolysis of cancer cells through binding to p21-activated kinase 1 (PAK1) in AML or SS cells plasma membrane, where PAK1 is overexpressed. In addition, JRT39 exerted potent anti-tumor activity in vivo in disseminated or subcutaneous AML, APL (Acute Promyelocytic Leukemia) and SS-patient derived preclinical murine models. Preliminary pharmacokinetic studies revealed that JRT39 is stable in human serum and has a plasma half-life of ~1.5-2.5 hours after intravenous (IV) administration to dogs or cynomolgus monkeys, with concentration-time data fitting 2-compartment model. Finally, JRT39 was well tolerated at 5 and 10 mg/kg after single or repeated (daily) IV injections.

Conclusions: Combined, our preclinical data confirm that interfering with AAC-11-related survival pathways is a promising novel anticancer strategy and support the development of JRT39 for the treatment of cancer.

Citation Format: Louise Jeammet, Emile Adicéam, Justine Habault, Anna Kaci, Jeannig Berrou, Mélanie Dupont, Nicolas Thonnart, Ewa Pasquereau-Kotula, Anne Marie-Cardine, Armand Bensussan, Marika Pla, Hervé Dombret, Claude Gardin, Martine Bagot, Jean-Christophe Rain, Hélène Sicard, Jérôme Tiollier, Thorsten Braun, Jean-Luc Poyet. AAC-11 survival pathways as therapeutic target in cancer: AAC-11 leucine-zipper domain derived peptides exert potent antitumor effects and exhibit favorable stability, pharmacokinetic and toxicology profiles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 464.

CD164 identifies CD4+ T cells highly expressing genes associated with malignancy in Sézary syndrome: the Sézary signature genes, FCRL3, Tox, and miR-214

Sézary syndrome (SS), a leukemic variant of cutaneous T-cell lymphoma (CTCL), is associated with a significantly shorter life expectancy compared to skin-restricted mycosis fungoides. Early diagnosis of SS is, therefore, key to achieving enhanced therapeutic responses. However, the lack of a biomarker(s) highly specific for malignant CD4+ T cells in SS patients has been a serious obstacle in making an early diagnosis. We recently demonstrated the high expression of CD164 on CD4+ T cells from Sézary syndrome patients with a wide range of circulating tumor burdens. To further characterize CD164 as a potential biomarker for malignant CD4+ T cells, CD164+ and CD164-CD4+ T cells isolated from patients with high-circulating tumor burden, B2 stage, and medium/low tumor burden, B1-B0 stage, were assessed for the expression of genes reported to differentiate SS from normal controls, and associated with malignancy and poor prognosis. The expression of Sézary signature genes: T plastin, GATA-3, along with FCRL3, Tox, and miR-214, was significantly higher, whereas STAT-4 was lower, in CD164+ compared with CD164-CD4+ T cells. While Tox was highly expressed in both B2 and B1-B0 patients, the expression of Sézary signature genes, FCRL3, and miR-214 was associated predominantly with advanced B2 disease. High expression of CD164 mRNA and protein was also detected in skin from CTCL patients. CD164 was co-expressed with KIR3DL2 on circulating CD4+ T cells from high tumor burden SS patients, further providing strong support for CD164 as a disease relevant surface biomarker.

Abstract 2473: KIR3DL2 is a novel target for antibody-therapy of T cell lymphomas

Intro:

The killer immunoglobulin-like receptor, three domains, long cytoplasmic tail 2 (KIR3DL2) is a transmembrane glycoprotein expressed by natural killer (NK) cells and subsets of T cells. On NK cells, KIRD3L2 modulates NK cell activation by transducing inhibitory signals upon ligation by human leukocyte antigen (HLA) class I molecules. Interestingly, KIR3DL2 is also expressed on several subtypes of T cell lymphomas/leukemias, such as Sézary Syndrome and transformed Mycosis Fungoides. This expression pattern provides a promising target for antibody-based therapy. Recently, antibody-based therapies have been shown to synergize with co-stimulatory immunomodulation via agonistic immunotherapeutic antibodies, such as anti-CD137.

Methods:

We evaluated the efficacy of an anti-KIR3DL2 monoclonal antibody, IPH4102 (Innate Pharma S.A.), in inducing effector cell cytotoxicity of KIR3DL2+ tumors. In vitro experiments utilized primary samples and three KIR3DL2+ cell lines: HUT78, a Sézary cell line with constitutive KIR3DL2 expression; a RAJI-KIR3DL2 high-expression sub clone with ∼28,000 KIR3DL2 antigen sites per cell; and a RAJI-KIR3DL2 low-expression sub clone with ∼ 6,000 antigens sites per cell. All antibody-mediated cell cytotoxicity (ADCC) experiments used 7-AAD and Annexin-V to identify apoptotic cells.

Results:

In a CD107a /IFN-γ assay, NK cells co-cultured with IPH4102-coated HUT78 cells demonstrated increased activation profiles relative to NK cells co-cultured with untreated HUT78 cells. Activated NK cells displayed elevated expression of CD137, OX40, and CD69 and produced more CD107a and IFN-γ. In allo-ADCC assays using HUT78 cells at varying target to effector ratios, IPH4102 treatment induced more target apoptosis than treatment with positive control anti-CD52 alemtuzumab. In additional allo-ADCC assays, RAJI-KIR3DL2 high-expression tumors demonstrated more apoptosis than RAJI-KIR3DL2 low-expression tumors. The IPH4102-mediated cytotoxicity could be enhanced by the concurrent administration of an agonistic anti-CD137 monoclonal antibody. In ADCC assays of primary Sézary cells with autologous NK cells, we confirmed the upregulation of KIR3DL2 and observed enhanced NK cytotoxicity following tumor treatment with IPH4102. Again, the combination of anti-KIR3DL2 and anti-CD137 therapy proved synergistic leading to increased tumor eradication relative to either therapy alone.

Conclusion:

Our findings support a role for anti-KIR3DL2 monoclonal antibodies in the treatment of KIR3DL2+ tumors. IPH4102 effectively increased ADCC of KIR3DL2+ tumors by NK cells. The addition of agonistic anti-CD137 antibodies will further augment the anti-tumor efficacy of this therapeutic strategy.

Citation Format: Cariad Chester, Sean Lim, Anne Marie-Cardine, Naren Rajasekaran, Hélène Sicard, Youn Kim, Holbrook Kohrt. KIR3DL2 is a novel target for antibody-therapy of T cell lymphomas. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2473. doi:10.1158/1538-7445.AM2015-2473

A novel targeted immunotherapy for CTCL is on its way: Anti-KIR3DL2 mAb IPH4102 is potent and safe in non-clinical studies

Cutaneous T-cell lymphomas (CTCLs) represent a group of rarely occurring and clinically and pathologically heterogeneous diseases that are considered incurable at advanced stages. Current treatments provide limited clinical benefit and are thus largely amenable to improvement. An antibody-based CTCL-specific immunotherapy targeting the KIR3DL2 receptor expressed by the tumor cells in CTCL is currently under development and has shown encouraging results in pre-clinical studies.

IPH4102, a humanized KIR3DL2 antibody with potent activity against cutaneous T-cell lymphoma

Advanced cutaneous T-cell lymphoma (CTCL) remains an unmet medical need, which lacks effective targeted therapies. In this study, we report the development of IPH4102, a humanized monoclonal antibody that targets the immune receptor KIR3DL2, which is widely expressed on CTCL cells but few normal immune cells. Potent antitumor properties of IPH4102 were documented in allogeneic human CTCL cells and a mouse model of KIR3DL2(+) disease. IPH4102 antitumor activity was mediated by antibody-dependent cell cytotoxicity and phagocytosis. IPH4102 improved survival and reduced tumor growth in mice inoculated with KIR3DL2(+) tumors. Ex vivo efficacy was further evaluated in primary Sézary patient cells, sorted natural killer-based autologous assays, and direct spiking into Sézary patient peripheral blood mononuclear cells. In these settings, IPH4102 selectively and efficiently killed primary Sézary cells, including at unfavorable effector-to-target ratios characteristic of unsorted PBMC. Together, our results offer preclinical proof of concept for the clinical development of IPH4102 to treat patients with advanced CTCL.

The PPARα pathway in Vγ9Vδ2 T cell anergy

Phosphoantigens (PAgs) activate Vγ9Vδ2 T lymphocytes, inducing their potent and rapid response in vitro and in vivo. However, humans and nonhuman primates that receive repeated injections of PAgs progressively lose their Vγ9Vδ2 T cell response to them. To elucidate the molecular mechanisms of this in vivo desensitization, we analyzed the transcriptome of circulating Vγ9Vδ2 T cells from macaques injected with PAg. We showed that three PAg injections induced the activation of the PPARα pathway in Vγ9Vδ2 T cells. Thus, we analyzed the in vitro response of Vγ9Vδ2 T cells stimulated with a PPARα agonist. We demonstrated that in vitro PPARα pathway activation led to the inhibition of the BrHPP-induced activation and proliferation of human Vγ9Vδ2 T cells. Since the PPARα pathway is involved in the antigen-selective desensitization of human Vγ9Vδ2 T cells, the use of PPARα inhibitors could enhance cancer immunotherapy based on Vγ9Vδ2 T cells.

What lessons can be learned from γδ T cell-based cancer immunotherapy trials?

During the last several years, research has produced a significant amount of knowledge concerning the characteristics of human γδ T lymphocytes. Findings regarding the immune functions of these cells, particularly their natural killer cell-like lytic activity against tumor cells, have raised expectations for the therapeutic applications of these cells for cancer. Pharmaceutical companies have produced selective agonists for these lymphocytes, and several teams have launched clinical trials of γδ T cell-based cancer therapies. The findings from these studies include hematological malignancies (follicular lymphoma, multiple myeloma, acute and chronic myeloid leukemia), as well as solid tumors (renal cell, breast and prostate carcinomas), consisting of samples from more than 250 patients from Europe, Japan and the United States. The results of these pioneering studies are now available, and this short review summarizes the lessons learned and the role of γδ T cell-based strategies in the current landscape of cancer immunotherapies.

Phase I study of bromohydrin pyrophosphate (BrHPP, IPH 1101), a Vgamma9Vdelta2 T lymphocyte agonist in patients with solid tumors

PURPOSE

Vgamma9Vdelta2 (gammadelta) T lymphocytes, a critical peripheral blood lymphocyte subset, are directly cytotoxic against many solid and hematologic tumor types. Vgamma9Vdelta2 T lymphocytes can be selectively expanded in vivo with BrHPP (IPH1101) and IL-2. The present phase I trial was conducted with the aim of determining the maximum-tolerated dose (MTD) and safety of IPH1101 combined with a low dose of IL-2 in patients with solid tumors.

EXPERIMENTAL DESIGN

A 1-h intravenous infusion of IPH11 was administered alone at cycle 1, combined with a low dose of SC IL-2 (1 MIU/M(2) d1 to d7) in the subsequent cycles (day 1 every 3 weeks). The dose of IPH1101 was escalated from 200 to 1,800 mg/m(2).

RESULTS

As much as 28 patients with solid tumors underwent a total of 109 treatment cycles. Pharmacodynamics data demonstrate that gammadelta T lymphocyte amplification in humans requires the co-administration of IL-2 and is dependent on IPH 1101 dose. Dose-limiting toxicity occurred in two patients at a dose of 1,800 mg/m(2): one grade 3 fever (1 patient) and one grade 3 hypotension (1 patient) suggesting cytokine release syndrome immediately following the first infusion. At lower doses the treatment was well tolerated; the most frequent adverse events were mild fever, chills and abdominal pain, without exacerbation in the IL-2 combined cycles.

CONCLUSION

IPH1101 in combination with SC low-dose IL-2 is safe, well tolerated and induces a potent gammadelta T lymphocyte expansion in patients. Its clinical activity will be evaluated in phase II clinical trials.

Large scale expansion of Vgamma9Vdelta2 T lymphocytes from human peripheral blood mononuclear cells after a positive selection using MACS "TCR gamma/delta+ T cell isolation kit"

Interest in gamma9delta2 T cells has increased greatly in the past decade. While several protocols allowed the amplification of a large proportion of these cells in vitro, the purity of the final preparation is usually heterogeneous between different donors. Functional studies of this population are often controversial due to the presence of other populations such as NK cells which share a wide range of characteristics. Here, the gamma9delta2 T cells labelled-fraction is purified and mixed with the irradiated unlabelled fraction followed by a single stimulation with phosphoantigen, in turn followed by a classical step of amplification in the presence of interleukin 2. In this study, we describe a straightforward protocol to amplify pure populations of gamma9delta2 T cells which could be useful in fundamental research or in the development of a new generation of gammadelta cell therapy protocol.

Synthesis and biological activity of phosphonate analogues and geometric isomers of the highly potent phosphoantigen (E)-1-hydroxy-2-methylbut-2-enyl 4-diphosphate

Gammadelta-T-lymphocytes contribute to innate immunity and are selectively activated by nonpeptide phosphorylated molecules (so-called phosphoantigens) produced by organisms responsible for causing a broad range of infectious diseases. gammadelta-T-cells are also activated by synthetic phosphoantigens and are cytotoxic to tumor cells. Here we report the synthesis, NMR characterization, and comparative biological evaluation of new pyrophosphate, phosphonate, and pyrophosphonate monoesters whose structures correspond to isosteric analogues and stereoisomers of the highly potent isoprenoid metabolite ( E)-1-hydroxy-2-methylbut-2-enyl 4-diphosphate called HDMAPP (hydroxy-dimethyl-allyl pyrophosphate). Both pyrophosphate and pyrophosphonate series elicit promising gammadelta-T-cell stimulatory responses in vitro, the pyrophosphonate ester (C-HDMAPP) being by far more stable than its parent pyrophosphate ester (HDMAPP) with improved ADMET properties and a similar pharmacodynamic profile based on in vivo studies in nonhuman primate. In both series, we found that E-stereoisomers are the most active derivatives and that Z-stereoisomers show very marginal bioactivity levels. These results indicate that the use of bioisosteric analogues of HDMAPP may represent promising new leads for immunotherapy.

Vγ9Vδ2 T (γδ) lymphocytes: a promising approach for immunotherapy of solid tumors

3064

Background: The Vγ9Vd2 T (γd) blood lymphocyte subset has a strong cytotoxic potential and can be selectively activated with chemically-synthesized, structural analogues of non-conventional antigens like BrHPP (IPH1101). Their proliferation requires low dose of Interleukin-2 (IL-2). Methods: We developed several in vitro and in vivo models to assess the immunotherapeutic potential of IPH1101-activated γd cells: - Direct cytotoxicity assays on patient-derived primary tumor cell lines - Extensive pharmacodynamics in the non human primate (NHP) - Small scale in vitro amplification assays for IPH1101-sensitive patient pre-selection Then, two Phase I clinical trials were performed in solid tumor patients: - Autologous cell therapy with ex vivo IPH1101- expanded γd cells (1, 4 or 8.109 cells) - Direct administration of IPH1101 (200 to 1800 mg/m2 i.v.) and low dose IL-2 (106 U/m2 s.c.). Results: In NHP, IPH1101 and low dose IL-2 induce early pro-inflammatory cytokine release and dose-dependent γd cell amplification in peripheral blood. In vitro, mRCC tumor cells are efficiently and selectively killed by autologous γd cells. In Phase I clinical trials, both ex vivo expanded γd cells and IPH1101 were well tolerated. - Cell therapy-related AEs included mainly gastrointestinal disorders, flu-like symptoms and hypotension. Six patients showed stabilized disease. Median duration of stabilization was 25.7 weeks. 2 pts treated with 4.109 or 8.109 cells showed substantial tumor shrinkage at the 14-week evaluation (-22% and -48%, respectively). - When IPH1101 was administered with low dose of IL-2, a significant increase of blood γd T cells was observed (up to 240 times the basal values) and in terms of clinical activity assessment, among the evaluable mRCC population (n=15), 8 patients presented disease stabilization for more than 35 weeks, including 6 for more than 51 weeks. Conclusions: For the first time, a specific γd immunotherapy was fully developed and led to Phase I clinical trials. It has been found well tolerated. Encouraging signs of disease stabilisation in mRCC patients suggest that γd may have a role in the treatment of cancers resistant to conventional therapies. A phase 2 is ongoing in mRCC patients.

No significant financial relationships to disclose.

A tuberculosis vaccine based on phosphoantigens and fusion proteins induces distinct gammadelta and alphabeta T cell responses in primates

Phosphoantigens are mycobacterial non-peptide antigens that might enhance the immunogenicity of current subunit candidate vaccines for tuberculosis. However, their testing requires monkeys, the only animal models suitable for gammadelta T cell responses to mycobacteria. Thus here, the immunogenicity of 6-kDa early secretory antigenic target-mycolyl transferase complex antigen 85B (ESAT-6-Ag85B) (H-1 hybrid) fusion protein associated or not to a synthetic phosphoantigen was compared by a prime-boost regimen of two groups of eight cynomolgus. Although phosphoantigen activated immediately a strong release of systemic Th1 cytokines (IL-2, IL-6, IFN-gamma, TNF-alpha), it further anergized blood gammadelta T lymphocytes selectively. By contrast, the hybrid H-1 induced only memory alphabeta T cell responses, regardless of phosphoantigen. These latter essentially comprised cytotoxic T lymphocytes specific for Ag85B (on average + 430 cells/million PBMC) and few IFN-gamma-secreting cells (+ 40 cells/million PBMC, equally specific for ESAT-6 and for Ag85B). Hence, in macaques, a prime-boost with the H-1/phosphoantigen subunit combination induces two waves of immune responses, successively by gammadelta T and alphabeta T lymphocytes.

In vivo immunomanipulation of V gamma 9V delta 2 T cells with a synthetic phosphoantigen in a preclinical nonhuman primate model

Vgamma9Vdelta2(+) cells represent the major population of gammadelta T cells in primate blood and react in an MHC-unrestricted fashion to a set of low m.w. nonpeptide phosphoantigens. Two types of structurally related agonists have been discovered so far: the natural phosphoantigens (hydroxydimethyl allyl-pyrophosphate or isopentenyl-pyrophosphate (IPP)) acting directly on Vgamma9Vdelta2(+) TCR and aminobisphosphonates, which block the mevalonate pathway in target cells, leading to accumulation of natural phosphoantigens that in turn activate Vgamma9Vdelta2(+) cells. We demonstrate in the cynomolgus monkey that Vgamma9Vdelta2 can be manipulated in vivo with bromohydrin pyrophosphate (BrHPP)/Phosphostim, a potent synthetic agonist for which the mechanism of action is similar to natural phosphoantigens. Although of very short half-life, injection of BrHPP leads to strong activation of Vgamma9Vdelta2, inducing production of a high level of Th1 cytokines. Combination of BrHPP with low-dose rhIL-2 induces specific amplification of effector-memory peripheral Vgamma9Vdelta2 in blood in a dose-dependant manner. This transient response returns to baseline within 10-15 days. Successive infusions of BrHPP and rhIL-2 induce less vigorous expansions, suggesting a progressive exhaustion of the response. As no toxicity is detected with or without IL-2, this scheme represents a promising immunotherapeutic strategy for induction of systemic Th1 cytokines and massive expansion of gammadelta T cell subset with antitumor and anti-infectious properties.

Diagnosis of cypress pollen allergy: in vivo and in vitro standardization of a Juniperus ashei pollen extract

BACKGROUND

Cypress pollen allergy is a major cause of rhinoconjunctivitis and asthma in the Mediterranean area. The nonstandardized cypress allergen extracts currently available for the diagnosis of cypress allergy have a low level of activity. The search for an active material has led to the selection of Juniperus ashei (Ja) pollen because of its very high cross-reactivity with cypress extracts and its superior allergenic activity. The aim of this study was to characterize in vitro and calibrate in vivo an in-house reference extract (IHRS) of J. ashei pollen and determine the specificity and sensitivity of a standardized Ja extract for the prick test diagnosis of cypress allergy.

METHODS

Juniperus ashei pollen extract was analysed by 2-D electrophoresis. The IHRS Ja extract was calibrated by skin prick testing in 28 cypress-allergic patients. The sensitivity and specificity of cypress allergy diagnosis using a standardized Ja extract was studied by skin prick test in 42 cypress-allergic patients and 53 nonallergic patients. Jun a 1 content of the IHRS was determined by a monoclonal antibody-based electrophoretic technique.

RESULTS

The Jun a 1 content of the 100 IR/ml Ja IHRS extract was 180 microg/ml. For in vivo diagnosis of cypress allergy, Ja pollen extract demonstrated a sensitivity of 95%, a specificity of 100%, a negative predictive value of 96%, and a positive predictive value of 100%.

CONCLUSION

Standardized Ja pollen extract is therefore a very appropriate tool for the in vivo diagnosis of cypress pollen allergy and good candidate for specific immunotherapy.

Synthetic phosphoantigens enhance human Vgamma9Vdelta2 T lymphocytes killing of non-Hodgkin's B lymphoma

BACKGROUND

Non-Hodgkin's B lymphomas (NHL) are often resistant to conventional treatments and, until now, immunotherapeutic approaches against NHL only aimed at inducing anti-tumor effectors. Nevertheless, human blood Vgamma9Vdelta2 T lymphocytes represent an abundant pool of cytotoxic tumor-reactive cells. Vgamma9Vdelta2 T cells are strongly activated by natural compounds, from which powerful synthetic ligands have been derived. These synthetic antigens induce efficient Vgamma9Vdelta2 T cell responses in vitro.

MATERIALS AND METHODS

We set up a series of Vgamma9Vdelta2 T cell-activation experiments, including cytotoxic activity and amplification from whole blood cells. Several types of Vgamma9Vdelta2 effectors were challenged against a panel of 16 B lymphoma cell lines. These tests have been performed in the absence and presence of -specific synthetic ligands to evaluate the effect of such molecules on anti-tumor activity.

RESULTS

We report here that Vgamma9Vdelta2 T cells recognize B lymphomas. This recognition is associated with the cytotoxic activity against B-lymphoma cells and/or proliferative responses, and appears to be T-cell antigen receptor (TCR)-dependent. Because few B lymphoma induce a complete set of Vgamma9Vdelta2 cell responses, a chemical ligand of Vgamma9Vdelta2 T cells was used to enhance both proliferation and cytotoxic activity of anti-B lymphoma effectors. We show that such synthetic compound improves Vgamma9Vdelta2 CTL numbers and lysis of B lymphoma lines, especially when the targets are already spontaneously recognized by these effectors.

CONCLUSIONS

We report here that human Vgamma9Vdelta2 T cells anti-B lymphoma response can be improved by use of specific synthetic ligands, which enhance their cytotoxic activity and allows their rapid expansion ex vivo.

Y2K+1 state-of-the-art on non-peptide phosphoantigens, a novel category of immunostimulatory molecules

Some human T cells are activated in vivo and in vitro by small non-peptide antigens, so-called phosphoantigens. Since their discovery in 1994, several reports have continuously documented novel members of this category of immunostimulatory molecules. This article reviews the current knowledge on their biochemical properties.

[Conjunctival provocation test with Dermatophagoides pteronyssinus in the diagnosis of allergic conjunctivitis from house mites]

INTRODUCTION

Perennial conjunctivitis due to house dust mites is the most frequent form of allergic conjunctivitis in urban environments. However, its diagnosis remains difficult for ophthalmologists. In this study, we evaluated a conjunctival provocation test (CPT) using standardized extracts of Dermatophagoides pteronyssinus (Dpt) and compared it to the diagnostic methods commonly performed in allergology: prick tests with dust and house dust mites and specific and IgE assay.

MATERIALS AND METHODS

We performed a CPT on 60 volunteer patients, between the ages of 8 and 64 years, corresponding to 30 patients sensitized to house dust mites with the presence of specific IgE and chronic conjunctivitis, 21 patients not sensitized to house dust mites but presenting features of chronic conjunctivitis, and 9 asymptomatic patients. A house dust mite desensitizing treatment was not an exclusion criterion for a number of allergic patients. CPTs were prepared from Dpt allergenic extracts (Laboratoires Stallergènes, Antony, France) with 5 progressive concentrations by dilution in a nonphenolic physiological solution: 1.2 RI, 3.7 RI, 11 RI, 33 RI, and 100 RI. CPTs were performed in only one eye and asymmetry of the ocular response was evaluated by the cumulative clinical score of Abelson Chambers and Smith. The correlation between the 2 diagnostic tests was established by calculating the Cohen correlation coefficient or kappa. We also evaluated the sensitivity and diagnostic specificity for each test.

RESULTS

The statistical correlation between specific IgE and the other allergological tests in for allergic conjunctivitis to house dust mites was 0.93 for the CPT, 0.46 for the prick test to Dpt, and 0.33 for the prick test to dust. The diagnostic sensitivities and specificities for each test were 90% and 100% for the CPT, 60% and 70% for the prick test to dust, 70% and 76% for prick test to Dpt, respectively. Beyond an antigenic cut-off value of 11 RI, we also observed greater hypersensitivity reactions for patients with lacrimal IgE or elevated specific IgE levels.

CONCLUSION

The results obtained with the CPT confirm its high antigenic quality. It is a particularly useful, rapid, and perfectly safe clinical test. It is the only test able to establish a relationship between ocular manifestations and specific I(8)E.

Safety of sublingual-swallow immunotherapy in children and adults

BACKGROUND

Immunotherapy is an established treatment of allergic diseases. The safety of this treatment, particularly when administered without direct medical surveillance, as in the case of the sublingual-swallow route needs to be established. The aim of this paper is to review the safety of the sublingual-swallow immunotherapy as reported in eight double-blind, placebo-controlled trials carried out in France, Italy and Greece.

METHODS

Six hundred and ninety subjects, 472 adults and 218 children, took part in trials of specific immunotherapy (SIT) for the treatment of rhinoconjunctivitis and/or asthma. Three hundred and forty-seven patients received SIT and 343 patients received placebo. Treatment with specific immunotherapy with allergen extracts or placebo was administered using the sublingual-swallow technique. The allergens administered were grass, ambrosia, parietaria and olive pollens, and mites. The daily dose taken during maintenance therapy ranged from 100 to 300 IR (index of reactivity) and cumulative doses ranged from 4,500 to 104,000 IR. Treatment duration ranged from 4 months to 2 years. Adverse events reported either spontaneously by the patient or on direct questioning by the investigator were analysed.

RESULTS

One hundred and forty-five unusual events were reported in the subjects receiving active SIT and 79 in those receiving placebo (p < 0.001). Of these 85 were children aged 15 years or less (50 received active SIT, 35 placebo) and 139 were adults (95 received SIT, 44 placebo). Unusual events involving the buccal cavity (61 SIT, 13 placebo) and the gastro-intestinal tract (47 SIT, 15 placebo) were significantly more frequent in the SIT-treated patients (p < 0.001). Wheezing (9 SIT, 21 placebo) was more frequent in the placebo-treated patients (p < 0.05). There were no differences in the frequency of unusual events between adults and children and in the frequency of events involving other body systems. No event was reported as serious. Two events reported as laryngeal oedema were not considered to be accurate descriptions.

CONCLUSIONS

No serious adverse event was reported in the studies monitored, confirming the good safety profile of the sublingual-swallow method both in children and adults with rhinitis or moderate asthma.

[Juniperus ashei: the gold standard of the Cuppressaceae]

The non-standardized Cupressus sempervirens allergen extract currently available for the diagnosis of cypress allergy has a low level of activity. The search for an active material consisted of in vitro and in vivo comparison of three Cupressaceae pollen extracts: Cupressus sempervirens (Cs), Cupressus arizonica (Ca) and Juniperus ashei (Ja) (synonyms: Juniperus sabinoides and Mountain Cedar). These 3 trees belong to the same botanical family of Cupressaceae. While Cs and Ca are commonly encountered in Mediterranean regions, Ja is only present in Europe in the Balkans, but is a major cause of allergy in the USA. In vitro, with a similar protein content, the allergenic properties of Ja extract are 20-Fold higher than those of Cs and 11-fold higher than those of Ca. IgE immunoblotting revealed 14, 42 and 70 kDa allergens common to all 3 extracts. The inhibition curves of the 3 extracts were more than 88% parallel. A significant correlation was observed between serum specific IgE titres for Ja and Cs in 23 patients (r = 0.916; p < 0.001). In vivo, in 23 patients with cypress allergy, the mean diameter of the prick test papule at 1/20 W/V of Ja (8.3 mm) was greater than that of the Cs papule (6.3 mm) (p = 0.001) and the Ca papule (6.7 mm) (p < 0.001). Correlations between cutaneous responses to Cs and Ja (r = 0.629; p = 0.002), and to Cs and Ca (r = 0.75; p = 0.001) were significant. These results demonstrate the intense cross-reactivity between Cs, Ca and Ja. The allergenic potency of the Ja extract is superior to that of Cs and Ca extracts, both in vitro and in vivo. This superiority is correlated with a high concentration of the major allergen, Jun a 1. The non-standardized The now standardized extract of in vitro ashei pollen therefore represents an effective and documented solution for identification, and probably for treatment, of Cupressaceae pollen allergy.

Structure and functions of nucleolin

Nucleolin is an abundant protein of the nucleolus. Nucleolar proteins structurally related to nucleolin are found in organisms ranging from yeast to plants and mammals. The association of several structural domains in nucleolin allows the interaction of nucleolin with different proteins and RNA sequences. Nucleolin has been implicated in chromatin structure, rDNA transcription, rRNA maturation, ribosome assembly and nucleo-cytoplasmic transport. Studies of nucleolin over the last 25 years have revealed a fascinating role for nucleolin in ribosome biogenesis. The involvement of nucleolin at multiple steps of this biosynthetic pathway suggests that it could play a key role in this highly integrated process.

The role of the Schizosaccharomyces pombe gar2 protein in nucleolar structure and function depends on the concerted action of its highly charged N terminus and its RNA-binding domains

Nonribosomal nucleolar protein gar2 is required for 18S rRNA and 40S ribosomal subunit production in Schizosaccharomyces pombe. We have investigated the consequences of the absence of each structural domain of gar2 on cell growth, 18S rRNA production, and nucleolar structure. Deletion of gar2 RNA-binding domains (RBDs) causes stronger inhibition of growth and 18S rRNA accumulation than the absence of the whole protein, suggesting that other factors may be titrated by its remaining N-terminal basic/acidic serine-rich domain. These drastic functional defects correlate with striking nucleolar hypertrophy. Point mutations in the conserved RNP1 motifs of gar2 RBDs supposed to inhibit RNA-protein interactions are sufficient to induce severe nucleolar modifications but only in the presence of the N-terminal domain of the protein. Gar2 and its mutants also distribute differently in glycerol gradients: gar2 lacking its RBDs is found either free or assembled into significantly larger complexes than the wild-type protein. We propose that gar2 helps the assembly on rRNA of factors necessary for 40S subunit synthesis by providing a physical link between them. These factors may be recruited by the N-terminal domain of gar2 and may not be released if interaction of gar2 with rRNA is impaired.

Ultrastructural changes in the Schizosaccharomyces pombe nucleolus following the disruption of the gar2+ gene, which encodes a nucleolar protein structurally related to nucleolin

The nucleolar protein gar2, from the fission yeast Schizosaccharomyces pombe, is the functional homolog of NSR1 from Saccharomyces cerevisiae, and is structurally related to nucleolin from vertebrates. By immunocytochemistry at the electron microscope level, we show that gar2 co-localizes with RNA polymerase I and the gar1 protein along the dense fibrillar component of the nucleolus in a wild-type strain of S. pombe, suggesting that gar2 is involved in the transcription and/or in the early steps of maturation of the ribosomal RNAs. Since the effects of disruption of the gar2+ gene might also shed light on the role of the gar2 protein, we analyzed the ultrastructure of the nucleolus of a gar2-disruption mutant. The nucleolus of the gar2- mutant is dramatically reorganized when compared with that of the wild-type gar2+ strain: a truncated protein containing the NH2-terminus of the gar2 protein is accumulated in an unusual nucleolar "dense body". Our results also suggest that the NH2-terminus might be sufficient for nucleolar localization via interaction with specific nucleolar components and support the hypothesis that gar2 in wild-type S. pombe interacts with nascent pre-rRNA via its two RNA-binding domains in combination with the glycine/arginine-rich domain. We also report that disruption of the gar2+ gene results in a mutant that is defective in cytokinesis and nuclear division.

Mitosis-specific phosphorylation of gar2, a fission yeast nucleolar protein structurally related to nucleolin

The nucleolar protein gar2 of fission yeast is structurally related to the multifunctional nucleolar protein nucleolin from vertebrates and has been shown to be implicated in production of 18S rRNA. gar2 contains several potential casein kinase 2 (CK2) phosphorylation sites and a single putative p34(cdc2 )phosphorylation site in the consensus S50PKK. Here, we show that, like nucleolin, gar2 is phosphorylated in vitro by both highly purified CK2 from CHO cells and p34(cdc2 )from starfish oocytes. Moreover, the substitution of alanine for the N-terminal serine 50 abolishes phosphorylation by p34(cdc2 )in vitro. We also provide evidence that gar2 is phosphorylated in vitro by a p13(suc1)-Sepharose-bound kinase from Schizosaccharomyces pombe extracts that displays cell cycle-regulated activity similar to that of the p34(cdc2(kinase. In vivo 32P labeling of cells indicates that gar2 is a phosphoprotein and that incorporation of phosphate on residue 50 occurs specifically at mitosis. Taken together, these results lead us to propose that gar2 is likely to be an in vivo substrate for the mitotic p34(cdc2 )kinase. However, this posttranslational modification of the gar2 protein does not appear to be essential for normal production of 18S rRNA.

Latex allergy diagnosis: in vivo and in vitro standardization of a natural rubber latex extract

For the diagnosis of IgE-mediated (immediate) hypersensitivity to natural rubber latex (NRL), skin prick testing with extracts of latex gloves has been widely used, but such extracts are difficult to standardize. The present study aimed to produce on an industrial scale an NRL extract from freshly collected NRL and to evaluate, calibrate, and standardize the extract by both in vivo and in vitro testing. The source material, latex of the rubber tree, Hevea brasiliensis (clone RRIM 600), was frozen immediately after collection in Malaysia and shipped in dry ice to Stallergènes SA, France. Protein and allergen profiles were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting, isoelectric focusing (IEF), crossed immunoelectrophoresis (CIE), and crossed radioimmunoelectrophoresis (CRIE). Allergen quantification was effected by RAST inhibition. The capacity of the preparation to elicit immediate hypersensitivity reactions in vivo was measured by skin prick testing in 46 latex-allergic patients and 76 nonallergic control subjects. SDS-PAGE and immunoblot profiles of the extract and an NRL standard (E8) provided by the US Food and Drug Administration were almost identical, disclosing several distinct IgE-binding proteins with apparent molecular weights of 14, 20, 27, 30, and 45 kDa, conforming to reported molecular weights of several significant NRL allergens. An arbitrary index of reactivity (IR) of 100 was assigned to the extract at 1:200 dilution (w/v), having a protein content of 22 micrograms/ml. Skin prick testing of latex-allergic patients and controls using the extract at 100 IR revealed 93% sensitivity, 100% specificity, 100% negative predictive value, and 96% positive predictive value. In conclusion, a skin prick test reagent for diagnosis of type I NRL allergy was successfully standardized. The reagent was demonstrated to contain most, if not all, of the currently known clinically significant NRL allergens, and it showed high sensitivity and specificity.

A double-blind, placebo-controlled trial by the sublingual route of immunotherapy with a standardized grass pollen extract

Fifty-eight patients with well-documented history of seasonal rhinoconjunctivitis caused by grass pollens were allocated randomly on a double-blind basis to receive either sublingual therapy with a solution of purified, standardized allergen preparation (Stallergènes) or a matched placebo for 17 weeks. The assessment of the effect of oral immunotherapy, done with drops of five-grass allergen extract, was on the clinical symptoms and on the medication score of the authorized rescue treatments. The actively treated patients had significantly (P < 0.05 to P < 0.01) fewer symptoms of rhinitis (sneezing and rhinorrhea) and of conjunctivitis (redness and tears) during the pollen season than the placebo group. Consumption of nasal solution of sodium cromoglycate and of betamethasone and dexchlorpheniramine was significantly less in the desensitized group (P < 0.01). Side-effects were negligible. This study concludes that perlingual immunotherapy with grass pollen extract in grass-pollen-sensitive seasonal hay fever and conjunctivitis patients is effective, easy to perform, inexpensive, and safe.

[Sublingual specific immunotherapy for rhinoconjunctivitis caused by grass pollens]

Fifty eight patients with rhino-conjunctivitis caused by grass pollen were included in a double-blind study in which they received, by the sub-lingual route over 5 months, either a solution of purified and standardised allergen or a placebo. Assessment of the effect of this immunotherapy, which was done with drops of Stallergenes "5-grass pollen" was by clinical symptoms and the use of authorized drugs and treatments. Compared with the placebo group, the patients on active treatment showed significantly less (P = 0.05 to P = 0.01) rhinitis symptoms (sneezing and rhinorrhea) and conjunctivitis (reddening and tears) during the pollen season. Consumption of nasal cromoglycate solution, of betamethasone and dexchlorpheniramine was significantly lower (p = 0.01) in the desensitised group. Secondary effects were negligible. From this study, it can be concluded that immunotherapy with grass pollen extract, by the sub-lingual route, of patients with rhino-conjunctivitis who were sensitive to these allergens, is efficacious, easy to do, economic and sure.