Francesco Puppo

Soluble HLA-A,-B,-C and -G molecules induce apoptosis in T and NK CD8+ cells and inhibit cytotoxic T cell activity through CD8 ligation.

There is convincing evidence that soluble HLA‐A,‐B,‐C (sHLA‐A,‐B,‐C) and soluble HLA‐G (sHLA‐G) antigens can induce apoptosis in CD8+ activated T cells although there is scanty and conflicting information about the mechanism(s) by which sHLA‐A,‐B,‐C antigens and sHLA‐G antigens induce apoptosis. In this study we have compared the apoptosis‐inducing ability of sHLA‐A,‐B,‐C antigens with that of sHLA‐G1 antigens in CD8+ T lymphocytes and CD8+ NK cells. Furthermore we have compared the inhibitory effect of sHLA‐A,‐B,‐C antigens and of sHLA‐G1 antigens on theactivity of EBV‐specific CD8+ cytotoxic T lymphocytes (CTL). sHLA molecules were purified from serum and from the supernatant of HLA class I‐negative cells transfected with one gene encoding either classical or non‐classical HLA class I antigens. Both classical and non‐classical sHLA class I molecules trigger apoptosis in CD8+ T lymphocytes and in CD8+ NK cells, which lack the T cell receptor, and their apoptotic potency is comparable. The binding of sHLA‐A,‐B,‐C and sHLA‐G1 molecules to CD8 leads to Fas ligand (FasL) up‐regulation, soluble FasL (sFasL) secretion and CD8+ cell apoptosis by Fas/sFasL interaction. Moreover, classical and non‐classical sHLA class I molecules inhibit the cytotoxic activity of EBV‐specific CD8+ CTL. As the amount ofsHLA‐G molecules detectable in normal serum is significantly lower than that of sHLA‐A,‐B,‐C molecules, the immunomodulatory effects of sHLA class I molecules purified from serum are likely to be mainly attributable to classical HLA class I antigens. As far as the potential in vivo relevance of these findings is concerned, we suggest that classical sHLA class I molecules may play a major immunoregulatory role in clinical situations characterized by activation of the immune system and elevated sHLA‐A,‐B,‐C serum levels. In contrast, non‐classical HLA class I molecules may exert immunomodulatory effects in particular conditions characterized by elevated sHLA‐G levels such as pregnancy and some neoplastic diseases.

The impaired NK cell cytolytic function in viremic HIV‐1 infection is associated with a reduced surface expression of natural cytotoxicity receptors (NKp46, NKp30 and NKp44)

Signals leading to NK cell triggering are primarily mediated by natural cytotoxicity receptors (NCR) upon binding to as‐yet‐undefined cell surface ligand(s) on normal hematopoietic cells, pathogen‐infected cells or tumor cells. In this study we tried to determine whether the decreased NK cell cytolytic function that is observed in HIV‐1‐infected patients may be related to a decreased expression of NCR. In HIV‐1‐infected patients, freshly drawn, purified NK cells expressed significantly decreased surface densities of NKp46 and NKp30 NCR. The low surface density of NKp46, NKp30 and NKp44 was also confirmed in in‐vitro‐activated NK cell populations and NK cell clones derived from HIV‐1 patients compared with uninfected donors. This defective NCR expression in HIV‐1 patients was associated with a parallel decrease of NCR‐mediated killing of different tumor target cells. Thus, the present study indicates that the defective expression of NCR represents at least one of the possible mechanisms leading to the impaired NK cell function in HIV‐1 infection and it can contribute to explain the relatively high frequency of opportunistic tumors reported in cohorts of untreated patients before the occurrence of profound immunosuppression (<200 CD4+ cells/mm3).

Impairment of CD8+ T Suppressor Cell Function in Patients with Active Systemic Lupus Erythematosus

Alteration of T cell suppression function has been recognized in patients with systemic lupus erythematosus (SLE). Recently, CD8+ T suppressor lymphocytes (CD8+ Ts) have been generated in vitro by incubating purified CD8+ T cells with IL-2 and GM-CSF. Using this method, we generated CD8+ Ts from patients affected by SLE. No major differences were found in the CD8+ Ts phenotype between SLE patients and healthy subjects. CD8+ Ts from SLE patients with active disease did not inhibit the anti-CD3 mAb-induced proliferation of autologous PBMC, whereas CD8+ Ts from SLE patients in remission exerted an inhibitory activity comparable to normal subjects. The inhibitory effect of CD8+ Ts cells was neither mediated by cytotoxic activity nor by apoptosis induction. Two cytokines, IFN-γ and IL-6, were found to be responsible for the function of CD8+ Ts. In fact, counteraction of CD8+ Ts suppression activity was obtained by blocking IFN-γ with a specific Ab or by inhibiting CD8+ Ts-mediated IL-6 secretion by an antisense oligonucleotide. Interestingly, CD8+ Ts from SLE patients showed a peculiar cytokine pattern characterized by an impaired secretion of IL-6 and an increased secretion of IL-12. Thus, it appears that an altered balance between inhibitory (IL-6) and stimulatory (IL-12) cytokines might be responsible for the functional impairment of CD8+ Ts in SLE patients.

Serum HLA class I antigens: markers and modulators of an immune response?

Abstract HLA class I antigens circulate in the serum in soluble form. This article discusses the clinical significance of levels of serum HLA class I antigens, both in patients with viral diseases and following organ transplantation, as well as the potential involvement of such antigens in the immune response.

Induction of interleukin 10 by sublingual immunotherapy for house dust mites: a preliminary report

BACKGROUND Subcutaneous specific immunotherapy has been demonstrated to be capable of inducing T-cell regulatory response. Interleukin 10 (IL-10) plays a crucial role in inducing allergen-specific tolerance; however, no previous studies have examined IL-10 production after sublingual immunotherapy (SLIT). OBJECTIVE To evaluate T-cell proliferation and IL-10 production in patients successfully treated with SLIT for house dust mites (HDMs). METHODS Peripheral blood mononuclear cells were isolated from patients after at least 3 years of successful HDM SLIT and from matched untreated allergic patients and healthy control subjects. After 3 and 6 days of in vitro stimulation with phytohemagglutinin (PHA), Candida albicans, and Dermatophagoides farinae, proliferation and production of IL-10 were measured. RESULTS Patients treated with SLIT showed a significant reduction of proliferation induced by C albicans compared with untreated atopic patients (P < .001), but a significant reduction was also demonstrated in healthy controls compared with untreated atopic patients (P < .001). Patients treated with SLIT also showed a significant increase of IL-10 production after Candida and PHA stimuli compared with patients with untreated rhinitis (P < .001 for both). Patients with untreated rhinitis did not produce IL-10. CONCLUSION This preliminary study confirms reduced T-cell proliferation and preliminarily provides the first evidence, to our knowledge, of peripheral IL-10 production in allergic patients successfully treated with HDM SLIT.

Anti-TNF-α Inhibitors: A New Therapeutic Approach for Inflammatory Immune-Mediated Diseases: An Update upon Efficacy and Adverse Events

The ongoing progresses in the knowledge of the pathogenic mechanisms of various inflammatory or immune-mediated diseases and the availability of innovative biotechnological approaches have lead to the development of new drugs which add to conventional treatments. TNF-α inhibitors (Infliximab, Adalimumab and Etanercept) have demonstrated efficacy either as monotherapy or in combination with other anti-inflammatory or disease modifying anti-rheumatic drugs (DMARDs). The efficacy and safety profile of the TNF-α inhibitors can be considered, in general, as a class effect. Nevertheless, some differences may exist among the three agents. In this paper, we will briefly review the indications for the use of the three TNF-α inhibitors, the pre-treatment considerations and the reported adverse events.

Prednisone increases apoptosis in in vitro activated human peripheral blood T lymphocytes.

Glucocorticoid hormones (GCH) regulate, through the apoptotic process, the negative selection of immature T cells in the thymus. Because apoptosis seems to occur also in the maintenance of peripheral tolerance, we have investigated whether GCH may induce apoptosis in human mature lymphocytes. Peripheral blood lymphocytes (PBL) or peripheral CD4+ and CD8+ T cell subsets were cultured in the presence of phytohaemaglutinin (PHA) or PHA and prednisone (PDN) at 10−3‐10−12M concentrations for 72, 96 and 120h. Cell cycle and membrane antigen expression were evaluated by flow cytometry and DNA degradation was detected by agarose gel electrophoresis. PDN blocks PBL growth in the G1 phase of cell cycle and inhibits both IL‐2 receptor (IL‐2R) expression and IL‐2 secretion. Apoptosis is clearly increased by PDN in PHA‐activated human PBL, and the apoptotic effect of PDN is stronger on CD8+ than on CD4+ T lymphocytes. All these effects are dose‐ and time‐dependent. The addition of exogenous IL‐2 did not rescue lymphocytes from PDN‐increased apoptosis. These results show that PDN increases apoptosis in mature activated human peripheral blood lymphocytes, suggesting a possible role of GCH in the maintenance of immune tolerance at post‐thymic level.

Current Views on Diagnostic Approach and Treatment of Lymphedema

Lymphedema is a chronic, progressive, and often debilitating condition. Primary lymphedema is a lymphatic malformation developing during the later stage of lymphangiogenesis. Secondary lymphedema is the result of obstruction or disruption of the lymphatic system, which can occur as a consequence of tumors, surgery, trauma, infection, inflammation, and radiation therapy. In this review, we report an update upon the diagnostic approach and the medical and surgical therapy for both primary and secondary lymphedema.

The role of Th17 lymphocytes in the autoimmune and chronic inflammatory diseases.

The emerging role of interleukin-17 as a hallmark proinflammatory cytokine of the adaptive immune system produced by a new T helper cell subset termed “Th17” has received considerable attention. In this review we will focus on recent information regarding IL-17 and its relevance in autoimmune and chronic inflammatory diseases.

Infection risk associated with anti-TNF-α agents: a review

Introduction: TNF-α is a pro-inflammatory cytokine known to a have a key role in the pathogenesis of chronic immune-mediated diseases. TNF-α inhibitors can be administered either as monotherapy or in combination with other anti-inflammatory or disease-modifying anti-rheumatic drugs (DMARDs) to treat chronic immune-mediated diseases. Areas covered: Patients receiving TNF-α inhibitors are at high risk of infections. Based on our experience, in this paper, we discuss the risk of infections associated with the administration of TNF-α inhibitors and the strategies for mitigating against the development of these serious adverse events. Expert opinion: Infliximab more so than etanercept appears to be responsible for the increased risk of infections. Re-activation of latent tuberculosis (LTB) infection and the overall risk of opportunistic infections should be considered before beginning TNF-α inhibitor therapy. A careful medical history, Mantoux test and chest-x-ray should always be performed before prescribing TNF-α inhibitors. Particular attention should be paid to risk factors for Pneumocystis jirovecii infection. Hepatitis B and C virological follow-up should be considered during TNF-α inhibitor treatment. Finally, patients who are at high risk of herpes zoster (HZ) reactivation would benefit from a second vaccination in adulthood when receiving TNF-α inhibitors.