Reduced progression of cardiac allograft vasculopathy with routine use of induction therapy with basiliximab.

INTRODUCTION: Cardiac allograft vasculopathy (CAV) is a major limitation for long-term survival of patients undergoing heart transplantation (HT). Some immunosuppressants can reduce the risk of CAV. OBJECTIVES: The primary objective was to evaluate the variation in the volumetric growth of the intimal layer measured by intracoronary ultrasound (IVUS) after 1 year in patients who received basiliximab compared with that in a control group. METHODS: Thirteen patients treated at a single center between 2007 and 2009 were analyzed retrospectively. Evaluations were performed with IVUS, measuring the volume of a coronary segment within the first 30 days and 1 year after HT. Vasculopathy was characterized by the volume of the intima of the vessel. RESULTS: Thirteen patients included (7 in the basiliximab group and 6 in the control group). On IVUS assessment, the control group was found to have greater vessel volume (120-185.43 mm3 vs. 127.77-131.32 mm3; p = 0.051). Intimal layer growth (i.e., CAV) was also higher in the control group (27.30-49.15 mm3 [∆80%] vs. 20.23-26.69 mm3[∆33%]; p = 0.015). Univariate regression analysis revealed that plaque volume and prior atherosclerosis of the donor were not related to intima growth (r = 0.15, p = 0.96), whereas positive remodeling was directly proportional to the volumetric growth of the intima (r = 0.85, p < 0.001). CONCLUSION: Routine induction therapy with basiliximab was associated with reduced growth of the intima of the vessel during the first year after HT.

Modeling the role of IL2 in the interplay between CD4+ helper and regulatory T cells: studying the impact of IL2 modulation therapies.

Several reports in the literature have drawn a complex picture of the effect of treatments aiming to modulate IL2 activity in vivo. They seem to promote indistinctly immunity or tolerance, probably depending on the specific context, dose and timing of their application. Such complexity might derives from the dual role of IL2 on T-cell dynamics. To theoretically address the latter possibility, we develop a mathematical model for helper, regulatory and memory T-cells dynamics, which account for most well-known facts relative to their relationship with IL2. We simulate the effect of three types of therapies: IL2 injections, IL2 depletion using anti-IL2 antibodies and IL2/anti-IL2 immune complexes injection. We focus in the qualitative and quantitative conditions of dose and timing for these treatments which allow them to potentate either immunity or tolerance. Our results provide reasonable explanations for the existent pre-clinical and clinical data and further provide interesting practical guidelines to optimize the future application of these types of treatments. Particularly, our results predict that: (i) Immune complexes IL2/anti-IL2 mAbs, using mAbs which block the interaction of IL2 and CD25 (the alpha chain of IL2 receptor), is the best option to potentate immunity alone or in combination with vaccines. These complexes are optimal when a 1:2 molar ratio of mAb:IL2 is used and the mAbs have the largest possible affinity; (ii) Immune complexes IL2/anti-IL2 mAbs, using mAbs which block the interaction of IL2 and CD122 (the beta chain of IL2 receptor), are the best option to reinforce preexistent natural tolerance, for instance to prevent allograft rejection. These complexes are optimal when a 1:2 molar ratio of mAb:IL2 is used and the mAbs have intermediate affinities; (iii) mAbs anti-IL2 can be successfully used alone to treat an ongoing autoimmune disorder, promoting the re-induction of tolerance. The best strategy in this therapy is to start treatment with an initially high dose of the mAbs (one capable to induce some immune suppression) and then scales down slowly the dose of mAb in subsequent applications.

Aspergillosis in patients treated with monoclonal antibodies.

Invasive aspergillosis is a disease typically related with prolonged neutropenia or the use of corticosteroids. However, the increased use of new therapeutic modalities such as biologic agents that act by blocking specific immune pathways have put more patients at risk for invasive aspergillosis. Most cases of aspergillosis in patients taking monoclonal antibodies have been associated with the use of tumour necrosis factor (TNF)-alpha blockers. However, many more drugs have been implicated, including interleukin-2 inhibitors, and CD52 and CD20 blockers. In this manuscript we review the pathophysiology associated with an increased risk for aspergillosis in these patients, in addition to diagnostic and therapeutic considerations.

Modulation of T cell responses in HTLV-1 carriers and in patients with myelopathy associated with HTLV-1.

OBJECTIVE: Human T lymphotropic virus-type 1 (HTLV-1) activates the immune system leading to a persistent and exacerbated T-cell response with increased production of IFN-gamma and TNF-alpha. Overproduction of pro-inflammatory cytokines is correlated with the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), although some HTLV-1 carriers also show high levels of these cytokines. In this study, the ability of regulatory cytokines and cytokine antagonists to inhibit spontaneous IFN-gamma production was investigated. METHOD: IFN-gamma levels were measured by ELISA before and after addition of cytokines or anti-cytokines. RESULTS: Addition of IL-10 significantly reduced spontaneous IFN-gamma synthesis in cell cultures from HTLV-1 carriers, while no differences were observed in HAM/TSP patients. There was also a tendency to decreased IFN-gamma levels in cell cultures from HTLV-1 carriers with exogenous addition of TGF-beta. In paired analysis, neutralization of IL-2 significantly decreased IFN-gamma production in HTLV-1 carriers but not in HAM/TSP patients. Neutralization of IL-15 was less effective than neutralization of IL-2 in modulating IFN-gamma production. In HTLV-1 carriers, anti-IL-2 and simultaneous addition of anti-IL-2 and anti-IL-15 decreased IFN-gamma synthesis by 46 and 64%, respectively, whereas in patients with HAM/TSP simultaneous neutralization of both anti-cytokines only decrease IFN-gamma levels by 27%. CONCLUSIONS: Although a large proportion of HTLV-1 carriers produced high levels of pro-inflammatory cytokines similar to those observed in HAM/TSP patients, immune response can be downregulated by cytokines or cytokine antagonists in most HTLV-1 carriers. This modulation can be an important step in the prevention of tissue damage and progression from the HTLV-1 carrier state to HAM/TSP.

Construction, purification, and characterization of a chimeric TH1 antagonist.

BACKGROUND: TH1 immune response antagonism is a desirable approach to mitigate some autoimmune and inflammatory reactions during the course of several diseases where IL-2 and IFN-gamma are two central players. Therefore, the neutralization of both cytokines could provide beneficial effects in patients suffering from autoimmune or inflammatory illnesses. RESULTS: A chimeric antagonist that can antagonize the action of TH1 immunity mediators, IFN-gamma and IL-2, was designed, engineered, expressed in E. coli, purified and evaluated for its in vitro biological activities. The TH1 antagonist molecule consists of the extracellular region for the human IFNgamma receptor chain 1 fused by a four-aminoacid linker peptide to human 60 N-terminal aminoacid residues of IL-2. The corresponding gene fragments were isolated by RT-PCR and cloned in the pTPV-1 vector. E. coli (W3110 strain) was transformed with this vector. The chimeric protein was expressed at high level as inclusion bodies. The protein was partially purified by pelleting and washing. It was then solubilized with strong denaturant and finally refolded by gel filtration. In vitro biological activity of chimera was demonstrated by inhibition of IFN-gamma-dependent HLA-DR expression in Colo 205 cells, inhibition of IFN-gamma antiproliferative effect on HEp-2 cells, and by a bidirectional effect in assays for IL-2 T-cell dependent proliferation: agonism in the absence versus inhibition in the presence of IL-2. CONCLUSION: TH1 antagonist is a chimeric protein that inhibits the in vitro biological activities of human IFN-gamma, and is a partial agonist/antagonist of human IL-2. With these attributes, the chimera has the potential to offer a new opportunity for the treatment of autoimmune and inflammatory diseases.

Interleukin-4 selectively inhibits interleukin-2 secretion by lipopolysaccharide-activated dendritic cells.

Dendritic cells (DCs) generated in vitro from bone marrow precursors using granulocyte-macrophage colony-stimulating factor (GM-CSF) secrete interleukin-2 (IL-2) upon activation, an event probably associated to the initiation of adaptive immune responses. Additionally, they produce IL-12, a cytokine related to T-cell polarization. To analyse the effect of IL-4 on DC differentiation and function, we assessed the capacity of murine bone marrow dendritic cells (BMDCs) differentiated with GM-CSF in the presence or absence of IL-4 to produce IL-2 and IL-12 upon lipopolysaccharide (LPS) activation. We found that although IL-4 enhanced DC IL-12p70 production, it strongly impaired IL-2 secretion by BMDCs. This inhibition, which depends on the presence of IL-4 during LPS activation, is DC specific, as IL-4 did not affect IL-2 secretion by T cells. Interestingly, inhibition of DC IL-2 production did not prevent DC priming of T lymphocytes. These results illustrate a new putative role for IL-4 on the regulation of the immune response and should help clarify the controversial reports on the effect of IL-4 on DCs.

Interleukin-2 and systemic lupus erythematosus--fifteen years later.

Systemic lupus erythematosus (SLE) is a highly heterogeneous disorder in which multiple immunologic abnormalities have been described. In this review, we thoroughly analyse the impaired T cell production of, and response to, interleukin-2 (IL-2) characteristic of patients with SLE. Since it was first reported, several articles have provided us with enlightening, but somewhat confusing, data that reveal the complexity of the subject. The IL-2 production by T cells is part of a complex network in which a discrete alteration is capable of disrupting the whole system. On the other hand, regulatory mechanisms exist that, in an attempt to compensate the primary alteration, provoke secondary defects. Evidence indicates that this defect is not intrinsic, but rather, results from multiple microenvironmental influences that act on the T cell and modify its activation state and its cytokine production. Abnormalities in co-stimulatory mechanisms and in cytokines that may be related to the IL-2 production deficiency, have been described in patients with SLE. We also consider the information derived from murine SLE models, IL-2 knockout models and reports concerning the immune dysregulation present in patients with SLE.

In vitro inhibitory activity of tumor necrosis factor alpha and interleukin-2 of human immunoglobulin preparations.

Human immunoglobulin preparations have been used in a number of clinical settings with good results, although in many of them the mechanism of action is not yet known. One possible mechanism is the modulation of cytokine activity. This study investigated the presence of inhibitory activity in intravenous immunoglobulin (IVIg) and F(ab')2 fragment preparations to two cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-2 (IL-2). Cytotoxic activity of human recombinant TNF-alpha or TNF-alpha secreted by peripheral blood mononuclear cells (PBMC) on L929 cells and the proliferative activity of the IL-2 on CTLL-2 cells were examined. Human serum albumin (HSA) was used as control. F(ab')2 inhibited, in a dose-dependent fashion, the TNF-alpha activity secreted by PBMC serial dilutions or, at the higher concentrations (25 and 10 mg/ml), recombinant TNF-alpha activity. In contrast, IVIg was able to inhibit only at 25 and 10 mg/ml the TNF-alpha activity secreted by any PBMC dilution tested, and did not inhibit the recombinant TNF-alpha activity. With IL-2, however, even HSA was able to inhibit its proliferative activity, possibly through a carrier effect. The IVIg inhibition of IL-2 activity was not different from that of HSA, but F(ab')2, at 12.5 mg/ml, was capable of inhibiting significantly more the IL-2 activity than HSA. Our results suggest an anticytokine effect of the immunoglobulin preparations that this activity may be mainly mediated by variable regions of the immunoglobulins, and that the more pronounced effect of F(ab')2 may be due to its greater molar concentration compared to intact IgG molecules.

Seminal plasma modulates lymphokine-activated killer cell activity in vitro.

We have previously reported that seminal plasma (SP) pool from donors and azoospermic patients can inhibit the NK response in vitro. In this study we investigated whether SP also inhibits the interleukin -2-activated natural cytotoxicity (LAK). Pools of SP from 10 healthy donors and 17 azoospermic patients were used. They were sterilized by filtration and stored at -20 degrees C until use. Anti-sperm antibodies were negative in all samples. Peripheral blood lymphocytes (PBL) obtained from volunteer donors were incubated during 16 hours in culture medium, RPMI alone, with 10% fetal calf serum (FCS) or with 10% human serum (HuS). The NK and LAK cytotoxicity assay was performed using the cell line K 562 labeled with 51Cr. In view of our results, we conclude that LAK activity is inhibited by SP when PBL are incubated in the absence of FCS. This inhibitory effect of SP is unrelated to cellular death and there is no difference between healthy and azoospermic seminal plasma.

Proliferación de leucocitos de sangre periférica en presencia de sueros de pacientes con cáncer cervicouterino e interleucina-2 recombinante / Proliferation of peripheral blood lymphocytes in presence of sera from patients with cervical cancer and interleukin-2

Diversos estudios han centrado su atención en el establecimiento de una técnica que permita activar y hacer responder de forma específica a linfocitos del paciente contra su propio tumor. Esto se ha conseguido en ocasiones activando linfocitos con mitógenos endógenos, como la interleucina-2 (IL-2). Sin embargo, se ha encontrado que algunos tumores secretan al torrente sanguíneo factores inhibidores de este tipo de respuesta inmune. Con la finalidad de determinar si las células de cáncer de cérvix (CaCu) secretan al torrente sanguíneo factores inhibidores de la respuesta proliferadora de linfocitos, en este trabajo se utilizaron sueros de 12 pacientes con CaCu en cultivos de leucocitos de sangre periférica (LSP). Para evaluar la posible inhibición de estos sueros en la activación mediada por la IL-2, se utilizaron tanto LSP de pacientes con CaCu como de donadores normales. Los resultados obtenidos muestran que in vitro no existe inhibición de la activación a la proliferación de LSP provenientes de pacientes con CaCu por la rIL-2, tanto en presencia de sueros normales como de pacientes con CaCu. En consecuencia, estos resultados indican que las células malignas que constituyen al CaCu probablemente no secretan factores inhibidores de la activación linfocitaria y que los LSP de estos pacientes no han perdido la capacidad de ser activados por la IL-2.