Increased expression of CD80, CD86 and CD70 on T cells from HIV-infected individuals upon activation in vitro: regulation by CD4+ T cells

T cells express CD28 and CD27 which transduce co-stimulatory signals after interaction with their ligands on antigen-presenting cells (APC). These ligands, CD80, CD86 and CD70, are also expressed to some extent on activated T cells. Here, we show that in human immunodeficiency virus (HIV)-infected individuals, CD28 and CD27 expression is decreased on CD8⁺ T cells. On the other hand, T cell stimulation in vitro induced high CD80, CD86 and CD70 expression on T cells from HIV-infected individuals. It appeared that an inverted CD4:CD8 T cell ratio could explain this enhanced expression of co-stimulatory ligands. Indeed, high expression levels of CD80, CD86 and CD70 were found on activated CD8⁺ T cells from HIV⁻ individuals cultured in the absence of CD4⁺ T cells. Addition of CD4⁺ T cells prevented this up-regulation. However, in HIV-infected individuals, addition of excess autologous or healthy control CD4⁺ T cells did not completely counteract up-regulation of co-stimulatory ligand expression on CD8⁺ T cells. Thus, to some extent, CD8⁺ T cells in HIV-infected individuals appeared to be refractory to CD4⁺ T cell-mediated regulation of ligand expression in vitro. Activated T cells from HIV-infected individuals and activated CD8⁺ T cells from healthy controls were able to act as accessory cells in CD3-induced T cell proliferation, which was dependent on cell-cell contact. Thus, we showed that T cells from HIV-infected individuals express enhanced levels of co-stimulatory ligands upon activation, which provides them with accessory cell properties. Enhanced stimulatory potential of these nonprofessional APC may contribute to persistently high levels of immune activation in HIV infection related to disease progression.     

Decreases in plasma TNF-alpha level and IFN-gamma mRNA level in peripheral blood mononuclear cells (PBMC) and an increase in IL-2 mRNA level in PBMC are associated with effective highly active antiretroviral therapy in HIV-infected patients

In this study, we investigated the cytokine profiles of 14 treatment-naive HIV-infected patients on the initiation of highly active antiretroviral therapy (HAART). At baseline, plasma levels of TNF-alpha and its mRNA in peripheral blood mononuclear cells (PBMC) were highest in the most severely immunocompromised patients (<200 CD4+ cells/mm3). After 12 months of HAART, the virus was undetectable in the plasma of all patients (<200 copies/ml), and median CD4 T cell counts had increased (+164 cells/mm3). We also observed a gradual decrease in the number of proviral DNA copies in PBMC and in immune activation, with lower levels of IFN-gamma mRNA in PBMC associated with weaker activation of CD8+ T cells and lower levels of plasma TNF-alpha. IL-2 mRNA levels in PBMC were found to increase in parallel. The decrease in TNF-alpha and IFN-gamma levels and the increase in IL-2 production appear to be correlated with the efficacy of HAART in naive immunocompromised HIV-infected individuals.     

Early Impairment of CD8+ T Cells Immune Response Against Epstein–Barr Virus (EBV) Antigens Associated with High Level of Circulating Mononuclear EBV DNA Load in HIV Infection

Immunodeficiency related to HIV may increase the incidence of EBV-associated lymphomas, by altering EBV-specific immune control and consequently favoring EBV reactivation. The aim of the present study was to assess the relationship between the decrease of EBV-specific cellular immunity and the increase of EBV reactivation in a prospective cohort of 72 unselected HIV-infected individuals. EBV-specific immunity was evaluated by a highly sensitive IFN-gamma ELISPOT assay using 22 peptides mimicking latent and lytic antigens, and circulating mononuclear (PBMC) EBV DNA load was quantified by real-time quantitative PCR. The mean circulating cell-associated EBV DNA load was higher in HIV-infected patients (639 copies/10(6) PBMC) than in healthy controls (21, n = 14) ( P = 0.005) and was higher in patients with CD4(+) T-cell count below 350/microL than that in patients harboring higher CD4(+) T-cell count (1112 vs. 389, P = 0.003). The mean intensity of EBV-specific cellular responses was lower in HIV-infected patients than in controls ( P = 0.001), even in patients with CD4(+) T-cell count above 350/-microL ( P = 0.007). The number of EBV peptides recognized was lower in HIV-infected patients than in controls (frequency: 0.44 vs. 0.67; P = 0.02), indicating reduced polyclonality in HIV-infected patients. The polyclonality was 1.5-fold lower in HIV-infected patients with CD4(+) T-cell count below 350/-microL ( P =0.007). For EBV load >1000 copies/10(6) PBMC, the levels of cell-associated EBV DNA and those of EBV-specific cellular immunity, either in intensity or in polyclonality, or both, were inversely correlated. These findings demonstrate early impairment of the EBV-specific cellular immune control with progressive increase of EBV reactivation in the course of HIV infection. These observations likely provide a basis for appreciating the risk to develop non-Hodgkin's lymphomas in HIV-infected individuals.     

Truncated thioredoxin: physiological functions and mechanism

Human cytosolic thioredoxin (Trx), which is the 12-kDa protein disulfide reductase with the Cys-Gly-Pro-Cys active site and a key component of cellular redox biochemistry and regulation, acts as cocytokine upon leaderless secretion. A 10-kDa C-terminally truncated thioredoxin (Trx80) comprising the 80 or 84 N-terminal amino acids is also secreted and present in plasma, where it originally was purified and identified as eosinophilic cytotoxicity enhancing factor. Recombinant Trx80 was discovered to be a potent mitogenic cytokine that stimulates growth of resting human peripheral blood mononuclear cells (PBMC) in a synthetic medium, an effect that Trx lacks. Trx80 is very different from Trx because it is a dimer lacking reductase activity and the cytokine activity is not dependent on the Cys residues of the Trx active-site motif. The primary targets of Trx80 in PBMC are monocytes that are activated to proliferate and increase expression of CD14, CD40, CD54, and CD86. Trx80 induces secretion of interleukin (IL)-12 in CD40+ monocytes from PBMC. Trx80 and IL-2 together were strongly synergistic to induce secretion of interferon-gamma in PBMC. Trx80 is a potent cytokine for monocytes directing the immune system to a Th1 response via IL-12 production.     

Peripheral blood mononuclear cells of HIV-infected patients contain CD8 T cells that form conjugates with and kill HIV-infected autologous CD4 T cells

Peripheral blood mononuclear cells (PBMC) of untreated, HIV-infected patients contain HIV-specific CD8 T cells as well as their corresponding targets, HIV-infected CD4 T cells. To determine if CD4 T-cell depletion in HIV-infected patients may result from autologous CD8–CD4 T-cell interaction, CD8 and CD4 T cells procured from PBMC of acute and chronic untreated HIV-infected patients were sorted and co-incubated. Formation of CD8-CD4 T-cell conjugates was observed by fluorescence microscopy. Apoptosis of CD4 T cells in conjugation was recorded by digitized images and was further observed and measured by FACS using Annexin staining. Perforin expression in the CD8 T cells was measured using intracellular monoclonal perforin antibody staining. HIV DNA in the conjugated CD4 T cells was detected by in situ PCR. We found that 6·1 ± 0·5% of CD4 T cells from acute HIV-infected patients and 3·0 ± 0·5% from chronic HIV-infected patients formed CD8–CD4 T-cell conjugates. Annexin binding and cell morphology typical of apoptosis were observed in the conjugated CD4 T cells. The majority of CD8 T cells that had conjugated to CD4 T cells expressed perforin. The conjugated CD4 T cells exhibited nuclear HIV DNA. CD8 T cells and HIV-infected CD4 T cells, both procured from the PBMC of untreated HIV-infected patients, form conjugates. Apoptotic lytic activity has been observed in the conjugated CD4 T cells. We propose that CD4 T-cell annihilation in HIV-infected patients results, at least in part, from the interactions of perforin-rich CD8 T cells with autologous, HIV-infected CD4 T cells.     

High levels of IL-10 and determination of other cytokines and chemokines in HIV-associated haemophagocytic syndrome

Haemophagocytic syndrome (HPS) and HIV infection are both associated with cytokine network dysregulation. We therefore analysed plasma levels and mRNA synthesis in peripheral blood mononuclear cells (PBMC) of cytokines, chemokines and chemokine receptors in one HIV-infected patient with HPS. We compared the results with those for eight HIV-infected patients with similar CD4+ T cell counts (207/mm3 versus controls: median 214/mm3) and plasma virus load (4.1 log copies/ml, versus controls: median 4.2 log copies/ml). The HPS patient had a lower viral DNA load in PBMC and higher plasma levels of interferon-gamma, IL-10, and macrophage inflammatory protein (MIP)-1beta. No difference in plasma tumour necrosis factor-alpha (TNF-alpha), IL-6 and MIP-1alpha concentration was observed between the HPS patient and control patients. No difference was observed in TNF-alpha, IL-1beta, IL-10, IL-4, MIP-1alpha, MIP-1beta, RANTES, CXCR-4, and CCR-5 mRNA levels in PBMC, but IL-6 levels were higher in the HPS patient. Our results emphasize the role of IL-10 in the control of immune hyperactivation that is observed in HPS.     

Altered Signaling Lymphocytic Activation Molecule (SLAM) Expression in HIV Infection and Redirection of HIV-Specific Responses via SLAM Triggering

Signaling lymphocytic activation molecule (SLAM) is a transmembrane lymphocytic receptor which gets rapidly upregulated following cell activation. SLAM engagement augments T cell expansion and interferon-gamma (IFN-gamma) production independently of CD28. SLAM signaling is regulated by the SLAM-associated protein. We evaluated the expression and function of SLAM on CD4(+) and CD8(+) lymphocytes in HIV-infected individuals with either recently acquired infection (Group A) or asymptomatic HIV infection (Group B) and in healthy controls (HC). Soluble antigen (HIV env peptides and tetanus toxoid)- and mitogen-stimulated proliferation and IFN-gamma and IL-10 production upon SLAM costimulation were also measured. Results showed that: (1) SLAM-expressing CD4(+) and CD8(+) lymphocytes diminish in group A patients compared to both group B patients and HC; (2) SLAM expression on CD4(+) lymphocytes is preferentially associated with the lack of CD7 on cell surface (CD4(+)CD7(-) produce IL-10 but not IFN-gamma); (3) SLAM engagement increases HIV env peptide-stimulated, but neither tetanus toxoid- nor PHA-stimulated proliferation of peripheral blood mononuclear cells (PBMC) in patients but not in HC; and (4) SLAM engagement augments IFN-gamma and reduces IL-10 production by env peptide-stimulated PBMC of HIV-infected individuals. These results demonstrate that early HIV infection results in an altered SLAM expression which correlates with a time-limited impairment of cell-mediated immunity. Furthermore, they show that triggering via SLAM potentiates HIV-specific proliferative responses with simultaneous downregulation of IL-10 and redirection of the response to TH0/TH1.     

IL-24对非小细胞肺癌患者CD8+T细胞体外功能的影响

目的观察IL-24在体外对非小细胞肺癌(non-small cell lung cancer,NSCLC)患者CD8⁺T细胞功能的影响。方法本研究入组28例NSCLC患者和17例健康对照者,收集外周血单个核细胞(peripheral blood mononuclear cells,PBMC)和支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF),分选CD8⁺T细胞,反转录实时定量PCR检测CD8⁺T细胞中IL-24受体(IL-20R1、IL-20R2和IL-22R1)mRNA的相对表达量。不同浓度重组人IL-24(10 ng/ml和100 ng/ml)刺激纯化CD8⁺T细胞后,流式细胞术检测穿孔素和颗粒酶B的表达变化。建立CD8⁺T细胞和NSCLC细胞系NCI-H1882细胞的直接接触和间接接触体外共培养系统,观察IL-24刺激后CD8⁺T细胞诱导靶细胞死亡比例,以及IFN-γ和TNF-α的表达变化。组间比较采用t检验或LSD-t检验。结果CD8⁺T细胞中未检测到IL-22R1 mRNA表达,CD8⁺T细胞中IL-20R1和IL-20R2 mRNA相对表达量在健康对照者和NSCLC患者之间以及在非肿瘤部位和肿瘤部位之间的差异均无统计学意义(P>0.05)。NSCLC患者外周血和肿瘤部位CD8⁺T细胞中穿孔素和颗粒酶B水平显著低于健康对照者和非肿瘤部位(P<0.05),低浓度IL-24(10 ng/ml)刺激不影响CD8⁺T细胞中穿孔素和颗粒酶B水平(P>0.05),而高浓度IL-24(100 ng/ml)则显著提升NSCLC患者CD8⁺T细胞中穿孔素和颗粒酶B水平(P<0.05)。直接接触共培养系统中,高浓度IL-24(100 ng/ml)刺激NSCLC患者肿瘤部位CD8⁺T细胞后可诱导靶细胞死亡比例升高,以及IFN-γ和TNF-α表达升高,而低浓度IL-24(10 ng/ml)刺激对CD8⁺T细胞诱导的靶细胞死亡和细胞因子分泌无显著影响。间接接触共培养系统中,IL-24刺激对CD8⁺T细胞诱导的靶细胞死亡和细胞因子分泌均无显著影响。结论高浓度IL-24在体外可增强NSCLC患者CD8⁺T细胞的直接细胞杀伤功能,但在体内IL-24可能并不影响CD8⁺T细胞的功能。     

HIV/AIDS患者疾病进程与CD4+CD25hi调节性T细胞之间相关性研究

目的 通过分析不同阶段HIV感染者外周血CD4+CD25hi调节性T细胞(CD4+CD25hiregulatory T cells,Treg cells)与外周血免疫状态和病毒载量的相关性,探讨Treg细胞对HIV/AIDS发病进程的影响.方法 采集116例HIV感染者和21例正常人对照外周血,用4色流式细胞术进行CD4+和CD8+T细胞绝对数计数;用3色流式细胞术进行Treg细胞测定;用荧光定量PCR法进行HIVRNA载晕测定.实验数据用回归统计学方法和T检验方法进行分析.结果 HIV感染者外周血Treg细胞频率在HIV感染初期显著下降,之后随着疾病的进程逐渐升高.在CD4+T细胞大于300/μl的患者低于正常对照组,在CD4+T细胞小于100/μl的患者高于正常对照组,差异具有统计学意义.Treg细胞频率与CD4+T淋巴细胞绝对数和CD4+/CD8+之间均呈负相关.其相关系数r和P值各为r=-0.564,P＜0.001和r=-0.377,P＜0.001;Treg细胞频率与血浆HIV病毒载量呈正相关,其相关系数r=0.514.P＜0.001.结论 CD4+CD25hi Treg细胞可能是参与艾滋病免疫发病机理的重要细胞,在HIV感染发病进程的不同阶段具有不同的意义,其确切机制有待进行进一步研究.     

Effect of HIV vertical transmission on the ontogeny of T cell antigens involved in the regulation of humoral immune response.

HIV infection causes progressive impairment of humoral immunity, including defective specific antibody production. To evaluate whether vertical HIV infection interferes with the expression on CD4+ lymphocytes of developmentally regulated molecules, that play a crucial role in the generation of immunological memory (CD45 isoforms) and in attainment of antibody responses (CD40L), 22 HIV-infected children and 36 seroreverted children born to HIV+ mothers were studied. The percentage of CD40L+ PBMC after activation in vitro with phorbol myristate acetate (PMA) plus ionomycin was lower in HIV-infected children than in controls (P < 0.004). This correlated with the depletion of CD4+ lymphocytes (r = 0.75; P < 0.001). CD40L expression rose progressively with age (r = 0.36; P = 0.03) in seroreverted children, but not in HIV-infected children, suggesting that while in normal children in vivo antigen stimulation results in progressive attainment of CD40L expression (and thus to effective T-B cell cooperation), this process is largely defective in HIV-infected children, contributing to the genesis of humoral immune deficiency. The proportion of CD4+ cells bearing the CD45RO isoform was increased among HIV-infected infants during the first years of life. However, the percentage of CD4+ CD45RO+ peripheral blood mononuclear cells (PBMC) progressively increased with age in controls (r = 0.69; P = 0.03), but not in HIV-infected children, showing that while vertical transmission of HIV does not prevent CD45RO expression early in life, it is associated with a disturbance of the physiological process of antigen priming, contributing to poor immunological memory to T cell-dependent antigens.     

Determination of CD59 protein in normal human serum by enzyme immunoassay, using octyl-glucoside detergent to release glycosyl-phosphatidylinositol-CD59 from lipid complex

In this study we have optimised the enzyme immunoassay (ELISA) to quantify CD59 antigen in human serum or plasma. The glycosyl-phosphatidylinositol (GPI)-linked form of CD59 is known to complex with serum high-density lipoprotein. For ELISA optimisation, therefore, we investigated the effect of detergents, added to the sample diluent, on the determined values of CD59. Values obtained in the presence of octyl-glucoside (OG) for 20 adults aged 18–35 years and 17 children 1–5 years old were, respectively, 33–119 ng/ml (mean ± S.D.: 66±22 ng/ml) and 37–143 ng/ml (76±33 ng/ml). These results were higher than those measured without OG and were in contrast with published results showing absence, or eight to nine times lower levels, of the protein in serum. A known range for serum concentrations of CD59 in healthy individuals will establish an important reference point for clinical work and for the investigation of diseases involving the complement membrane attack complex (MAC) and its regulation.     

Immunologic characteristics of HIV-infected individuals who make broadly neutralizing antibodies

Induction of broadly neutralizing antibodies (bnAbs) capable of inhibiting infection with diverse variants of human immunodeficiency virus type 1 (HIV-1) is a key, as-yet-unachieved goal of prophylactic HIV-1 vaccine strategies. However, some HIV-infected individuals develop bnAbs after approximately 2-4 years of infection, enabling analysis of features of these antibodies and the immunological environment that enables their induction. Distinct subsets of CD4⁺ T cells play opposing roles in the regulation of humoral responses: T follicular helper (Tfh) cells support germinal center formation and provide help for affinity maturation and the development of memory B cells and plasma cells, while regulatory CD4⁺ (Treg) cells including T follicular regulatory (Tfr) cells inhibit the germinal center reaction to limit autoantibody production. BnAbs exhibit high somatic mutation frequencies, long third heavy-chain complementarity determining regions, and/or autoreactivity, suggesting that bnAb generation is likely to be highly dependent on the activity of CD4⁺ Tfh cells, and may be constrained by host tolerance controls. This review discusses what is known about the immunological environment during HIV-1 infection, in particular alterations in CD4⁺ Tfh, Treg, and Tfr populations and autoantibody generation, and how this is related to bnAb development, and considers the implications for HIV-1 vaccine design.     

The effects of CD40- and interleukin (IL-4)-activated CD23+ cells on the production of IL-10 by mononuclear cells in Graves' disease: the role of CD8+ cells

The possible roles of CD8+ cells in the abnormal T cell-dependent B-cell activation in Graves' disease were investigated by analysing lymphocyte subsets in peripheral blood mononuclear cells (PBMC) and their production of soluble factors and cytokines such as IL-10 in patients with Graves' disease, Hashimoto's thyroiditis and normal controls. The PBMC were separated into CD8+ and CD8-depleted cells by magnetic separation columns, and cultured for 7 days with or without anti-CD40 monoclonal antibodies and IL-4. The culture supernatant was assayed for sCD23 and IL-10 using EIA, and the remaining cells were analysed by flow cytometry. Stimulation with anti-CD40 antibody together with IL-4 increased sCD23 levels and the number of CD23+ cells. The latter was further augmented by depletion of CD8+ cells. This combination of B cell stimulants increased production of IL-10 by PBMC from patients with Graves' disease. The CD40- and IL-4-activated production of IL-10 was decreased by CD8+ cell depletion. In contrast, constitutive production of IL-10 was increased after CD8+ cell depletion in a group of patients with low basal secretion levels (<35 ng/ml). It was, however, decreased in a group with higher basal production levels, but such a relationship was not found in the normal control group. Thus, T cell-dependent B-cell activation via a CD40 pathway activates CD23+ cells, leading to over-production of IL-10 and a shift of the Th1/Th2 balance to Th2 dominance, while CD8+ cells may suppress this activation to counteract the Th2 deviation in Graves' disease.     

HIV-infected children with moderate/severe immune-suppression: changes in the immune system after highly active antiretroviral therapy

The objective of this study was to monitor the changes in the immune system of HIV-infected children with moderate or severe immunodeficiency after highly active antiretroviral therapy (HAART), comprising a follow-up study in 14 HIV-infected children on HAART at two time points separated approximately by 11.8 +/- 0.4 (9.9; 15.4) months. HIV-infected children had significantly lower TREC levels than the control group, but 1 year after HAART the levels increased significantly (P < 0.05). In contrast, viral load (VL) did not change significantly. A positive correlation between T cell receptor excision circle (TREC) levels and both CD4(+) T cell absolute counts (r = 0.558; P = 0.05) and percentages (r = 0.625; P = 0.030) was found. During follow-up on HAART, the percentages and absolute counts of naive CD4(+) and CD8(+) T cell subsets were increased significantly (P < 0.05). CD4(+) CD45RA(hi+) CD62L(+), CD4(+) CD45RA(+) and CD4(+) CD38(+) percentages, and the CD8(+) CD45RA(hi+) CD62L(+) counts reached similar values to the control group. Also, CD8(+) CD45RO(+) CD38(+) and CD8(+) CD45RO(+) percentages, and CD8(+) CD45RO(+) CD38(+) absolute counts (P < 0.05) decreased with respect to the baseline. Lymphoproliferative responses to pokeweed mitogen (PWM) before HAART were lower in HIV-infected children than the control group, but they recovered to normal levels after a year on HAART. Tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma production by PHA-activated peripheral blood mononuclear cells (PBMC) was lower before HAART (P < 0.001), but reached similar levels to the control group 1 year after HAART. In HIV-infected children IgG, IgG(1) and IgG(3) plasma levels decreased significantly after HAART. The immune system reconstitution induced by HAART in HIV-infected children seems to be the consequence of decreased immune system activation and naive T cell reconstitution, mainly of thymic origin.     

Detection of a Soluble Form of the Leukocyte Surface Antigen CD48 in Plasma and Its Elevation in Patients with Lymphoid Leukemias and Arthritis

Proteins with glycosylphosphatidylinositol (GPI) anchors exhibit a range of activities and some of these proteins exist in both a membrane-associated and a soluble form. CD48 is a 47-kd GPI-linked glycoprotein which is expressed on T and B lymphocytes, monocytes, and many lymphoid malignancies. The biological function of CD48 is unknown. We describe the detection of a soluble form of CD48 in plasma and serum. Its level was quantified by an immunoenzymometric assay (IEMA) specific for soluble CD48. While soluble CD48 was detected in the plasma of healthy individuals (median = 29 ng/ml; range, 15–48 ng/ml), elevated levels were detected in some patients with lymphoproliferative disease (median = 41 ng/ml; range, 9–213 ng/ml), arthritis (median = 42 ng/ml; range, 13–67 ng/ml), and acute EBV infection (174 ng/ml). Soluble CD48 was also detectable in tissue culture supernatants from the Raji lymphoid cell line. The mechanism of CD48 release from cells is unclear. The finding of significant levels of soluble CD48 in plasma and the development of a sensitive IEMA for its measurement will facilitate further studies on its normal function and its role in disease.     

Concentrations of Soluble CD95 and CD8 Antigens in the Plasma and Levels of CD8+CD95+, CD8+CD38+, and CD4+CD95+ T Cells Are Markers for HIV-1 Infection and Clinical Status

Apoptosis mediated via the CD95 (FAS/APO-1) receptor is thought to play a role in the depletion of CD4+ T cells in HIV infection. In the present study expression of the CD95 antigen on lymphocyte subsets and the plasma level of soluble CD95 (sCD95) were determined in HIV-1-infected adults. The expression of CD95 was increased on CD8 cells in all groups of HIV+ individuals, while increased expression of CD95+ cells on CD4 cells was limited to individuals with CD4 counts of <200 mm³. The proportion of CD4+ that expressed CD95 was inversely correlated with the percentage of CD4+ PBL. The concentration of sCD95 was significantly higher in the plasma of HIV-infected individuals than in normal controls. The level of sCD95 in HIV-infected subjects showed no correlation with the percentage of PBL expressing CD95, indicating that the increased level of sCD95 did not reflect release from CD95+ PBL. The plasma sCD95 concentration was significantly correlated with the percentage of CD8+ cells and, particularly, with CD8+CD38– cells. A striking inverse correlation was found between the sCD95 plasma concentration and the proportion of CD4+CD95+ cells out of the total CD4+ population. There was no correlation between the serum level of sCD95 and that of soluble CD8 (sCD8), both of which were increased in the plasma of HIV+ individuals. Unlike the level of sCD95, the level of sCD8 in the plasma of HIV+ individuals. Unlike the level of sCD95, the level of sCD8 in the plasma of HIV+ individuals was correlated with the percentage of CD95+ and CD8+CD38+ cells. The present study indicates that plasma sCD95 may be one of the factors that regulate apoptotic death of lymphocytes in HIV infection.     

IL-5 production by CD4+ T cells of asthmatic patients is suppressed by glucocorticoids and the immunosuppressants FK506 and cyclosporin A

IL-5 was produced in vitro by peripheral blood mononuclear cells(PBMC) of mite-sensitive atopic patients upon challenge withspecific allergen, while PBMC of healthy controls produced essentiallyno IL-5. Stimuli delivered by the combination of phorbol esterand Ca²⁺ ionophore induced marked IL-5 production by PBMC obtainedfrom atopic and non-atoplc asthmatics, suggesting that bothprotein kinase C and Ca²⁺ Influx are required for IL-5 production.CD2- or CD4-bearlng cell depletion almost completely removedIL-5-produclng cells while CD8-bearing cell depletion ratherenriched them. These findings indicate that CD4⁺ T cells arethe principal source of IL-5 in PBMC. The capacity of PBMC ofatopic asthmatics, non-atopic asthmatics and healthy controlsto produce IL-2, IL-4, IL-5 and IFN- was compared, to find thatcytokine-producing capacities other than that of IL-5 (IL-2,IL-4 and IFN-) were not significantly different among the threegroups. Dexamethasone, FK506 and cyclosporin A suppressed IL-5production in vitro in a dose-dependent manner. Clear dose-dependentsuppression of IL-5 gene expression by FK506 was also observed.Treatment of asthmatic patients with inhaled glucocorticoid(beclomethasone dipropionate) ameliorated clinical symptoms,improved lung function and markedly suppressed IL-5 productionby PBMC, suggesting the essential role of IL-5 in the pathogenesisof bronchial asthma and the clinical importance of its regulation.     

Phenotypic expression of integrin membrane receptors on spontaneously proliferating CD8 cells in human T-lymphotropic virus type II (HTLV-II)-infected individuals

Spontaneous lymphocyte proliferation in the absence of exogenous stimulators was examined in asymptomatic HTLV-II-seropositive (n=12) and seronegative individuals (n=16). Mean spontaneous lymphocytic proliferation significantly increased on day 8 postculture in HTLV-II-infected individuals (5762±899 cpm) compared with normal controls (2034±925 cpm,P<0.01). The proliferating cells in infected individuals were predominantly T cells; neither B cells nor monocytes demonstrated any proliferation. Phenotypic analysis of cultured cells from individuals with HTLV-II infection demonstrated differential expression of integrin molecules as defined by anti-CD29 and anti-S6F1 (42.8±4.2 and 39.6±5.9%, respectively) on CD8 cells, as compared with day 0 peripheral blood mononuclear cells (PBMC) from infected individuals (19.7±3.5 and 19.9±1.9%, respectively) or normal controls (12.9±3.1 and 11.5±2.5%, respectively;P<0.001 for both comparisons). These CD8⁺ cells did not express CD16 or CD11b. The culture supernatants derived from the spontaneously proliferating cells had significantly increased levels of sCD8 and sCD25 (765±180 and 1805±320 U/ml, respectively) compared with those from normal controls (222±120 and 305±90 U/ml, respectively;P<0.01). Furthermore, culture supernatants derived from spontaneously proliferating PBMC from HTLV-II-infected individuals had no detectable levels of HTLV antigen and did not stimulate proliferation of PBMC from normal donors. These results suggest that the spontaneous proliferation in HTLV-II asymptomatic carriers is due to expansion of CD8 cells expressing integrin receptors which may serve as costimulatory molecules for their activation.     

Spontaneous abortion is associated with elevated systemic C5a and reduced mRNA of complement inhibitory proteins in placenta

Spontaneous abortion in early pregnancy due to unknown reasons is a common problem. The excess complement activation and consequent placental inflammation and anti‐angiogenic milieu is emerging as an important associated factor in many pregnancy‐related complications. In the present study we sought to examine the expression of complement inhibitory proteins at the feto–maternal interface and levels of complement split products in the circulation to understand their role in spontaneous abortion. Consenting pregnant women who either underwent elective abortion due to non‐clinical reasons (n = 13) or suffered miscarriage (n = 14) were recruited for the study. Systemic levels of complement factors C3a and C5a were measured by enzyme‐linked immunosorbent assay (ELISA). Plasma C5 and C3 protein levels were examined by Western blot. Expressions of complement regulatory proteins such as CD46 and CD55 in the decidua were investigated by quantitative polymerase chain reaction (PCR) and Western blot. The median of plasma C3a level was 82·83 ng/ml and 66·17 ng/ml in elective and spontaneous abortion patients, respectively. Medians of plasma C5a levels in elective and spontaneous abortion patients were 0·96 ng/ml and 1·14 ng/ml, respectively. Only plasma C5a levels but not C3a levels showed significant elevation in spontaneous abortion patients compared to elective abortion patients. Further, there was a threefold decrease in the mRNA expressions of complement inhibitory proteins CD46 and CD55 in the decidua obtained from spontaneous abortion patients compared to that of elective abortion patients. These data suggested that dysregulated complement cascade may be associated with spontaneous abortion.     

Serum and effector-cell antibody-dependent cellular cytotoxicity (ADCC) activity remains high during human immunodeficiency virus (HIV) disease progression

The activity of both serum and effector cell antibody-dependent cellular cytotoxicity (ADCC) against human immunodeficiency virus (HIV-1, HIV) was assessed in HIV-infected individuals. The goal was to relate ADCC levels with the stage or progression of HIV disease. Serial serum samples, usually collected at 6-month intervals, from individuals at defined stages of HIV disease (sero-conversion, the HIV-seropositive period before AIDS, and around the time of clinical AIDS diagnosis) were tested. HIV-coated CEM tumor cells were used as targets. Effector-cell ADCC activity was evaluated using fresh peripheral blood mononuclear cells (PBMC) from HIV-infected individuals at different stages of HIV disease. Samples were obtained from male homosexual participants in the Multicenter AIDS Cohort Study (MACS). In seroconverters, ADCC-inducing HIV-specific antibodies were detected at the time that the ELISA antibody test was first positive. Within several months, serum ADCC activity stabilized in each individual. In 29 HIV-seroprevalent individuals (HIV seropositive on their first visit), serum ADCC activity remained constant regardless of whether the individual's HIV disease was stable (high stable CD4;n=9) or rapidly deteriorating (sharply declining CD4,n=10; AIDS progressors,n=10). With respect to effector-cell activity, PBMC from HIV-infected individuals with or without AIDS were capable of mediating ADCC with heterologous and usually with autologous sera. Although the level of NK cytotoxic activity and the level of antibody-armed effector cell activity have been reported to decline as disease progresses, our results support previous observations that ADCC effector-cell activity against antibody-coated targets does not decline in HIV infection. These results indicate that both serum and effector cells with ADCC activity are present in HIV-infected individuals shortly after seroconversion and are maintained throughout HIV disease. Although levels of serum and effector-cell ADCC activity do not predict whether an individual will develop AIDS, CD4 cells which express HIV antigens (either produced endogenously or adsorbed onto the surface) could serve as targets for anti-HIV-mediated ADCCin vivo. ADCC could, thereby, contribute to CD4 T-cell depletion in infected individuals. However, since serum and effector-cell ADCC levels do not seem to relate to disease stage or progression, the protective or pathogenic role that ADCC plays in HIV-disease remains unresolved.