Restoration of TRAIL-induced apoptosis in resistant human pancreatic cancer cells by a novel FAK inhibitor, PH11.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) emerges as one of the most-promising experimental cancer therapeutic drugs and is currently being tested in clinical trials. However, both intrinsic and acquired resistance of human cancer cells to TRAIL-induced apoptosis poses a huge problem in establishing clinically efficient TRAIL therapies. To assess the regulation of TRAIL-resistance in human pancreatic cancer cells, we studied the TRAIL resistant pancreatic cell line PANC-1. We show that treatment with PH11, a novel Focal Adhesion Kinase (FAK) inhibitor in association with TRAIL rapidly induces apoptosis in TRAIL-resistant PANC-1 cells, but not in normal human fibroblast cells. To explain sensitization, we showed that PH11 restores TRAIL apoptotic pathway in PANC-1 cells through down-regulation of c-FLIP via inhibition of FAK and the phosphatidylinositol-3 kinase (PI3K)/AKT pathways. These findings suggest that this combined treatment may offer an attractive therapeutic strategy for safely and efficiently treating pancreatic cancer.

Anti-HBV DNA vaccination does not prevent relapse after discontinuation of analogues in the treatment of chronic hepatitis B: a randomised trial--ANRS HB02 VAC-ADN.

OBJECTIVE: The antiviral efficacy of nucleos(t)ide analogues whose main limitation is relapse after discontinuation requires long-term therapy. To overcome the risk of relapse and virological breakthrough during long-term therapy, we performed a phase I/II, open, prospective, multicentre trial using a HBV envelope-expressing DNA vaccine. DESIGN: 70 patients treated effectively with nucleos(t)ide analogues for a median of 3 years (HBV DNA <12 IU/mL for at least 12 months) were randomised into two groups: one received five intramuscular injections of vaccine (weeks 0, 8, 16, 40 and 44) and one did not receive the vaccine. Analogues were stopped after an additional 48 weeks of treatment in patients who maintained HBV DNA <12 IU/mL with no clinical progression and monthly HBV DNA for 6 months. The primary endpoint was defined as viral reactivation at week 72 (HBV DNA >120 IU/mL) or impossibility of stopping treatment at week 48. RESULTS: Reactivation occurred in 97% of each group after a median 28 days without liver failure but with an HBV DNA <2000 IU/mL in 33%; 99% of adverse reactions were mild to moderate. Immune responses were evaluated by enzyme-linked immunosorbent spot and proliferation assays: there was no difference in the percentage of patients with interferon-γ secreting cells and a specific T-cell proliferation to HBcAg but not to HBsAg after reactivation in each group. CONCLUSIONS: Although it is fairly well tolerated, the HBV DNA vaccine does not decrease the risk of relapse in HBV-treated patients or the rate of virological breakthrough, and does not restore the anti-HBV immune response despite effective viral suppression by analogues. TRIAL REGISTRATION NUMBER: NCT00536627.

Immunological and antiviral responses after therapeutic DNA immunization in chronic hepatitis B patients efficiently treated by analogues.

A substudy of a phase I/II, prospective, multicenter clinical trial was carried out to investigate the potential benefit of therapeutic vaccination on hepatitis B e antigen-negative patients with chronic hepatitis B (CHB), treated efficiently with analogues. Patients were randomized in 2 arms, one receiving a hepatitis B virus (HBV) envelope DNA vaccine, and one without vaccination. At baseline, HBV-specific interferon (IFN)-γ-producing T cells were detected in both groups after in vitro expansion of peripheral blood mononuclear cells. Vaccine-specific responses remained stable in the vaccine group, whereas in the control group the percentage of patients with HBV-specific IFN-γ-producing T cells decreased over time. The vaccine-specific cytokine-producing T cells were mostly polyfunctional CD4(+) T cells, and the proportion of triple cytokine-producer T cells was boosted after DNA injections. However, these T-cell responses did not impact on HBV reactivation after stopping analogue treatment. Importantly, before cessation of treatment serum hepatitis B surface antigen (HBsAg) titers were significantly associated with DNA or HBsAg clearance. Therapeutic vaccination in CHB patients with persistent suppression of HBV replication led to the persistence of T-cell responses, but further improvements should be searched for to control infection after treatment discontinuation.

[Cryptococcal meningo-encephalitis in an apparently immunocompetent patient]. / Cryptococcose neuroméningée chez un sujet en apparence immunocompétent.

INTRODUCTION: Cryptococcal meningo-encephalitis is a rare disease occurring more frequently in immunocompromised hosts. CASE REPORT: We report the case of an apparently immunocompetent patient who developed a recurrent neurological deficit with lymphocytic meningitis. The time from the first symptoms to diagnosis was 8 months. We noted mild CD4+ lymphocytopenia (500 cells/mm3) without HIV infection. CD4+ lymphocytes were not reactive for a panel of antigens. CONCLUSION: This case illustrates the usefulness of cerebrospinal fluid Cryptococcus Neoformans antigen test in patients with an unexplained neurological syndrome with a lymphocytic meningitis together with quantification of circulating lymphocytes clusters and analyse of their function in opportunistic infections.

Cell-mediated and not humoral immune responseis responsible for partial protection against toxoplasmosis in SCID mice reconstituted with human PBMC

El objetivo de este estudio fue profundizar en el conocimiento de la respuesta inmunologica especifica contra Toxoplasma en humanos. Usamos ratones SCID reconstituidos con PBMC de donantes sanos con y (..)(CNS) (AU)

The aim of this study was to further our understanding of the human Toxoplasma-specific immune response. We used severe combined immune deficiency (SCID) mice that had been reconstituted with peripheral blood mononuclear cells (PBMC) from healthy donors with and without serum Toxoplasma antigens(PBMC Toxo+ and PBMC Toxo-, respectively) and subsequently infected with parasite cysts. The specific lymphocyte proliferation rate (LPR) was higher for PBMC from Toxoplasma-immune donors and these PBMC secreted more Th1 cytokines than those obtained from Toxoplasma-non-immune donors. The engraftmentof human parasite-immune cells significantly increased the survival rate following infection compared to in unreconstituted animals,where as the engraftment of human non-parasite-immune cells did not alter the survival rate. Specific human anti-Toxoplasma antibodies were found in both groups of humanised animals, suggesting that the humoral immune response does not play a major role in this protection. Ten days after infection, cytometry revealed that there were more human CD45+ cells in the spleen and peritoneum of mice from the PBMC Toxo+ group than from the PBMC Toxo- group. Furthermore, plasma levels of nitric oxide(NO) peaked at an early stage of infection in resistant animals.Finally, no human CD4 mRNA or IFN-¦Ã mRNA was found in the brain during infection. All together, our results suggest that the human cell-mediated immune response provides partial protection against toxoplasmic encephalitis (TE) in this model. However,the effector mechanisms involved may be located outside of the central nervous system (CNS) (AU)

Cell-mediated and not humoral immune response is responsible for partial protection against toxoplasmosis in SCID mice reconstituted with human PBMC

El objetivo de este estudio fue profundizar en el conocimientode la respuesta inmunológica específica contra Toxoplasma enhumanos. Usamos ratones SCID reconstituidos con PBMC dedonantes sanos con y sin antígenos séricos de Toxoplasma (PBMCToxo+ and PBMC Toxo-, respectivamente) y subsecuentementeinfectados con cistos de parásito. La proliferación linfocitaria especifica(LPR) fue mayor en los PBMC de los donantes immunes aToxoplasma y éstos PBMC secretaron más citocinas Th1 que losobtenidos de donantes no immunes a Toxoplasma. La implantaciónde células inmunológicas de humanos infectados augmentósignificativamente la supervivencia después de la infección silo comparamos con la de los animales no reconstituidos. Sinembargo, la implantación de células inmunológicas de humanosno infectados no alteró la supervivencia. Se encontraron anticuerposespecíficos humanos anti- Toxoplasma en los dos gruposde animales humanizados, lo que sugiere que la respuesta inmunológicahumoral no juega un papel determinante en ésta protección.Diez días después de la infección, los estudios de citometríarevelaron que había más células humanas CD45+ en el bazoy peritoneo de los ratones del grupo PBMC Toxo+ que en los delgrupo Toxo-. Además, los niveles plasmáticos de óxido nítrico(NO) alcanzaron un máximo en un estadío más temprano de lainfección en animales resistentes. Finalmente, no se encontróRNAm de CD4 o IFN-gama humanos en el cerebro durante la infección.Nuestros resultados sugieren que la respuesta humana inmunológicacellular aporta una protección parcial contra la encephalitistoxoplásmica (TE) en este modelo. Sin embargo, los mecanismosefectores involucrados podrían estar localizados fuera delsistema nervioso central (CNS)

The aim of this study was to further our understanding of thehuman Toxoplasma-specific immune response. We used severecombined immune deficiency (SCID) mice that had been reconstitutedwith peripheral blood mononuclear cells (PBMC) fromhealthy donors with and without serum Toxoplasma antigens(PBMC Toxo+ and PBMC Toxo-, respectively) and subsequentlyinfected with parasite cysts. The specific lymphocyte proliferationrate (LPR) was higher for PBMC from Toxoplasma-immunedonors and these PBMC secreted more Th1 cytokines than thoseobtained from Toxoplasma-non-immune donors. The engraftmentof human parasite-immune cells significantly increased the survivalrate following infection compared to in unreconstituted animals,whereas the engraftment of human non-parasite-immunecells did not alter the survival rate. Specific human anti-Toxoplasmaantibodies were found in both groups of humanised animals, suggestingthat the humoral immune response does not play a majorrole in this protection. Ten days after infection, cytometry revealedthat there were more human CD45+ cells in the spleen andperitoneum of mice from the PBMC Toxo+ group than from thePBMC Toxo- group. Furthermore, plasma levels of nitric oxide(NO) peaked at an early stage of infection in resistant animals.Finally, no human CD4 mRNA or IFN-gamma mRNA was found in thebrain during infection. All together, our results suggest that thehuman cell-mediated immune response provides partial protectionagainst toxoplasmic encephalitis (TE) in this model. However,the effector mechanisms involved may be located outsideof the central nervous system (CNS)

[Resistance to HIV1 infection in exposed uninfected individuals: light and shadow in the research of mechanisms]. / Résistance au VIH1 chez les individus exposés non infectés : la recherche des mécanismes entre lumière et zones d'ombre.

Some individuals, dubbed here « EU ¼ (exposed but uninfected), do not show any sign of infection in spite of repeated exposures to HIV1. For more than ten years a considerable research effort is made to uncover the mechanisms of resistance to HIV1 in EUs including host factors of protection. Two main not exclusive hypotheses are explored : 1) EUs are resistant to HIV1 infection ought to antiviral innate defences, either genetic or immune ; 2) EUs are protected from infection by immune specific responses that neutralise or eliminate the virus. Various mechanisms have been associated to the resistance to HIV1 infection in studies on different high-risk populations, although none of them can explain all the cases. The resistance to HIV1 infection seems to be linked to the contribution of multiple factors whose relative weight can differ according to EUs ethnic origin, environment and way of exposure.

Partial restoration of cytokine profile despite reconstitution of cytomegalovirus-specific cell-mediated immunity in human immunodeficiency virus-infected patients during highly active antiretroviral treatment.

We reconstituted cytomegalovirus (CMV)-specific T-cell responses in human immunodeficiency virus-1-positive, CMV-positive patients receiving highly active antiretroviral treatment (HAART). We used several combinations of functionality parameters to determine the degree of T-lymphocyte reconstitution obtained during 1 year of treatment. Untreated patients displayed CMV-specific cytotoxic T-lymphocyte (CTL) activity despite the absence of CMV-specific lymphoproliferative responses (LPRs) and despite the fact that interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) were not secreted. The absence of LPRs, IFN-gamma and IL-2 before antiretroviral treatment suggests that CMV-specific immunity was deregulated despite the high CD4+ T-cell counts presented by our cohort, which are critical to the reactivation of CMV disease. After 6 months of HAART, CTL activity had increased compared with the baseline, as had the levels of secreted IFN-gamma and LPR. However, the levels of specific IL-2 produced did not change during therapy, and no specific IL-2 was detected during the follow-up period. Taken together, our findings suggest that 1 year of HAART led to the recovery of some, but not all, CMV-specific responses in our cohort of patients.

Temporary restoration of immune response against Toxoplasma gondii in HIV-infected individuals after HAART, as studied in the hu-PBMC-SCID mouse model.

We studied immune reconstitution against the parasite T. gondii in HIV-infected patients treated for 1 years with highly active antiretroviral therapy (HAART). We used SCID mice, humanized with peripheral blood mononuclear cells (PBMC) from patients, which were then infected with T. gondii cysts. Mice humanized with PBMC from patients before the start of HAART were highly susceptible to infection. In contrast, mice humanized with PBMC from patients who had received HAART for 6 months displayed higher survival rates, correlating with lower intracerebral parasite loads. However, this resistance was lost during follow up because mice humanized with PBMC from patients treated with HAART for 12 months survived for no longer than mice that had not been humanized. Specific lymphocyte proliferation assays showed that the increase in proliferative response depended on treatment duration and that HAART induced changes in IFN-gamma secretion in the presence of Toxoplasma antigens. Thus, our results indicate partial immune reconstitution against T. gondii in HIV-infected patients following HAART, possibly due to changes in the patterns of specific IFN-gamma production and redistribution of functional memory CD4+ cells.

Modulación de la respuesta inmunitaria por la proteína p-24 HIV-1: evidencias de un efecto diferencial sobre la respuesta alogénica in vitro / Modulation of immune response by HIV-1 p24 protein: evidence for a differential effect in allogeneic response in vitro

Es conocido que el virus de la inmunodeficiencia humana (VIH), el agente etiológico del sîndrome de la inmunodeficiencia adquirida humana (SIDA), induce un profundo desajuste de la respuesta inmunitaria, incluso en las etapas tempranas de la infección cuando los individuos son asintomáticos y clínicamente estables. La suceptibilidad y la progresión de la infección pueden ser explicadas por diferencias entre las distintas especies de VIH; sin embargo, varios estudios han descrito una asociación entre la expresión del TCR-V y el complejo mayor de histocompatibilidad (HLA) en los pacientes infectados por el VIH. También ha sido reportado que la respuesta inmunitaria aloespecífica juega un papel importante durante la fase aguda de la infección pudiendo inducir protección contra la infección, probablemente por la elimination de las células infectadas en etapas tempranas.Nosotros estudiamos el papel de la proteína recombinante p-24 HIV-1 durante la inducción de una respuesta alogénica in vitro y observamos que la p-24 HIV-1 es capaz de inducir tanto un aumento de la respuesta alogénica como también una disminución de la misma. Las moléculas HLA (clase I) podrían estar jugando un papel importante en los resultados obtenidos, ya sea incrementando o disminuyendo la respuesta alogénica. Por lo tanto, durante la aloestimulación, la proteína p-24 HIV-1 pudiera estar desempeñando un papel en la transmisión de la infección por el VIH aumentando las células blanco del virus (AU)

CD4 T cell recovery is slower in patients experiencing viral load rebounds during HAART.

To determine whether viral load rebounds during HAART impact on CD4+ T cell recovery and immune reconstitution, we studied a prospective cohort of 355 antiretroviral naive patients enrolled to be randomized in a trial of three strategies of induction/maintenance HAART. The extent of immune reconstitution in blood through 72 weeks of antiretroviral treatment was evaluated. Lymphocyte subset markers (CD4, CD8, CD45RA, CD62L, CD16, CD19), activation markers (HLA-DR, CD38, CD25) were performed by cytometry analysis. Our results showed that plasma HIV-1 RNA was suppressed to below 500 copies per ml through week 72 in 240 patients (group 1) while the remaining 115 patients experienced at least one viral rebound (group 2). At baseline, CD4 cell count was higher and HIV-1 RNA was lower in group 1 than in group 2. Over 72 weeks, mean increase in CD4+ T cell count was 0.32 cell/mm3/day in group 1 and only 0.14 cell/mm3/day in group 2 (P < 0.0001). However, the patterns of changes in CD4+ and CD8+ T cell subsets during therapy were very similar across the two groups with only subtle and very limited differences. We conclude that permanent control of HIV replication could be necessary for faster immune reconstitution.

Frequency and phenotyping of human immunodeficiency virus (HIV)-specific CD8+ T cells in HIV-infected children, using major histocompatibility complex class I peptide tetramers.

HLA-A*02 tetramers complexed to human immunodeficiency virus (HIV) Gag SLYNTVATL and HIV Pol ILKEPVHGV peptides were used to characterize HLA class I-restricted CD8(+) T cells in 41 HIV-infected children. The frequencies and the phenotype of specific circulating CD8(+) T cells were determined in whole-blood samples by means of cytometric analysis. Background staining of 13 HLA-A*02-negative patients showed that the frequency of CD8(+) T cells was <0.01%. Of the 28 HLA-A*02-positive patients, blood samples from 26 stained positive at least once the Gag tetramer (mean CD8(+) T cells, 0.87%; range, 0.1%-3.9%), and blood samples from 21 stained positive for the Pol tetramer (mean CD8(+) T cells, 0.59%; range, 0.1%-5.5%). The tetramer-binding cells were CD28(-), CD45RA(-), CD45RO(+), HLA-DR(+), and CD69(-) T lymphocytes. HIV-specific CD8(+) T cells can be detected easily in peripheral blood of HIV-infected children, using HLA tetramers combined with HIV peptides. These cells are memory activated CD28(-)CD8(+) T lymphocytes.

Functional monocyte-derived dendritic cells can be generated in chronic lymphocytic leukaemia.

Chronic lymphocytic leukaemia (CLL) remains an incurable disease. Although modern available treatments are able to induce disease regression, relapse almost inexorably occurs. Therefore, novel therapeutic strategies aimed at reducing the disease relapse rate are very much needed. Among these, the induction of tumour-associated antigen-specific cytotoxic T lymphocytes (CTL), through either DNA vaccines or injection of idiotype pulsed dendritic cells (DCs), has been actively investigated with encouraging preliminary results in B-cell malignancies. As the CLL B lymphocyte characteristically expresses low amounts of surface immunoglobulin (Ig) and T cells from these patients have been reported to display impaired functional activity, there are concerns related to the possibility of generating specific cytotoxic antitumoral T cells in this disease. In addition, no information is presently available regarding the functional ability of CLL-derived DCs. In the present work, freshly purified monocytes from CLL patients and normal donors were induced to differentiate in granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 serum-free medium and compared for their morphological, phenotypic and functional characteristics. Our results demonstrate that: (1) functional DCs can be generated from CLL patients with similar phenotype and function to those observed from normal donors; (2) in contrast to normal control subjects, monocyte-derived DCs from CLL patients spontaneously secrete endogenous IL-10; and (3) interferon (IFN)-gamma in combination with CD40L plays a major role in priming DCs from CLL patients for IL-12 and IL-15 production. Overall, these results indicate that it is possible to derive functionally competent DCs from circulating monocytes in CLL patients.

Short-term bioeffects of an infrared pulsed laser device on burned rat skin monitored by transverse relaxation times (NMR).

BACKGROUND AND OBJECTIVE: The aim of this study was to determine whether the application of an infrared pulsed laser device (IPLD) on the burned skin of rats induced significant changes in the water dynamics of the burned tissues as measured by nuclear magnetic resonance (NMR) at a proton frequency of 90 MHz by using transverse relaxation times (T2, I/T2). STUDY DESIGN/MATERIALS AND METHODS: Seven groups (GI-GVII), each consisting of four albino rats (Sprague-Dawley), of 12-14 weeks of age were used in the experiment. Rats in GI-GVI were anesthetized and burned with a hot tip. GI, GIII, GV were not irradiated. GII, GIV, GVI were irradiated at 0 hours; 0 and 24 hours; and 0, 24, and 48 hours, respectively. Rats in GVII served as controls and were neither burned nor irradiated. Samples from all groups were obtained and monitored by NMR by using transverse relaxation times (T2 and 1/T2). An unpaired Student's t-test and a one-way analysis of variance (ANOVA I) were preformed on the mean values obtained (T2, 1/T2). The statistical design was chosen to give a 95% power of contrast 1-beta (1/T2). The modulated beam of the IPLD used is composed of two superposed waves; a carrier wave (3 MHz), and a drive force wave in the near infrared (904 nm, f = 1014 Hz). A dose of 1.5 x 10(3) J/M2 per session was applied by placing the IPLD directly over the burned tissue by using a top-hat distribution. RESULTS: The results of a t-test on the T2 and 1/T2 values did not show statistically significant differences at 0 and 24 hours between the irradiated groups, the nonirradiated groups, and the nonburned nonirradiated (control) group. Nonetheless, at 48 hours after the burn, we found a statistically significant difference in the 1/T2 values for the irradiated specimens compared with the nonirradiated specimens and the control group. Furthermore, the variance of the 1/T2 values as a function of time showed a tendency to decrease significantly only for the irradiated specimens. CONCLUSION: These findings show possible effects on the water dynamics of burned rat tissue in a short term as a result of the IPLD's application.

Flow cytometric analysis of protein-tyrosine phosphorylation in peripheral T cell subsets. Application to healthy and HIV-seropositive subjects.

This paper describes an improved method for detecting tyrosine phosphorylation levels in T cell subsets by flow cytometry early after CD3 crosslinking stimulation. It consists in introducing gentle paraformaldehyde fixation between CD3 crosslinking in cold conditions and the shift to 37 degrees C, which activates downstream signalling machinery. We used the combined properties of monoclonal antibodies for stimulating cells and for detecting surface markers to analyze protein-tyrosine phosphorylation levels in T cells subsets following stimulations which mimic physiological activation. Overall data obtained in healthy subjects, using two- or three-color immunofluorescence, indicated that: (1) most CD3 positive cells phosphorylate tyrosine substrates following CD3 crosslinking stimulation and (2) helper cells phosphorylate tyrosine to a slightly better extent than cytotoxic cells after CD3 crosslinking. Nevertheless, the two subsets follow similar kinetic patterns and tend to retain a homogeneous profile. Processing of samples from HIV-seropositive patients showed heterogeneous phosphorylation levels in both subsets, when compared to normal donors. This assay should, in the future, lead to easy and rapid exploration of the signal transduction pathway in different subsets of T cells under normal and pathological conditions.

Viral superantigen-induced hyporesponsiveness of T cells and polyclonal B cell activation in HIV-1 infection.

The mechanisms of CD4 depletion and hyporesponsiveness during human immunodeficiency virus (HIV) infection are still unknown. Given the ability of superantigens to stimulate a higher number of lymphocytes than conventional antigens, they may play a major role in this process. Recently, a novel superantigen, the rabies virus nucleocapsid (NC), was described in humans. In the present work, we tested the responses of peripheral blood lymphocytes from asymptomatic HIV-infected patients to this superantigen. In contrast to its effect in normal controls, NC failed to expand T cells from HIV-infected individuals expressing the V beta 8 family, and induced a strong decrease in the response to CD3 activation. This absence of response was not the consequence of programmed cell death, and was explained by an anergic state induced by the superantigen. NC superantigen was also able to induce polyclonal activation of B cells, as measured by the secretion of anti-HIV antibodies and autoantibodies. Moreover, V beta 8 depletion experiments showed that induction of autoantibody secretion was V beta 8 dependent, whereas secretion of HIV-1 antibody was not. Interleukin secretion studies showed that NC was able to induce high levels of interleukin-4 and interleukin-10. Taken together, our results suggest a role for exogenous viral superantigens such as NC in the induction of T cell hyporesponsiveness and polyclonal B cell activation during HIV infection. The induction of a Th2 response and the role of these superantigens in the immunopathogenesis of acquired immunodeficiency syndrome are discussed.

Neonatal deletion and selective expansion of mouse T cells by exposure to rabies virus nucleocapsid superantigen.

The nucleocapsid (NC) of the rabies virus behaves as an exogenous superantigen (SAg) in humans. In the present report, we analyzed whether it is also a SAg in mice by studying the effect of NC on T cell receptor (TCR) V beta expression in BALB/c mice. Repeated injection of NC in newborn BALB/c mice led to a marked reduction by two- to sixfold of V beta 6 expressing CD4+ T cells in spleen and in peripheral blood. Decrease of V beta 6-expressing CD3+ mature T cells was also observed in thymus. Single NC injection in footpad resulted in a three- to sixfold expansion of V beta 6 CD4+ T cells, but not of CD8+ T cells, in the draining lymph nodes of BALB/c mice. The intensity of the stimulation was dose dependent and was maximal 3 d after the NC injection. The clonal deletion of T cells bearing a particular V beta demonstrates that NC is a SAg in mice. T cells, especially CD4+ T cells, are an essential factor in host resistance to rabies virus and also in the pathophysiology of paralysis; thus, we postulate that a rabies virus component, which stimulates T cells, such as a SAg, may increase virus immunopathogenicity. To evaluate this hypothesis, we compared the course of rabies in adult BALB/c lacking V beta 6, 7, 8.1, and 9 T cells and in normal BALB/c. Immune-related paralysis was decreased in BALB/c missing the NC target V beta T cells. Transfer of V beta 6 but not of V beta 8.1-3 T cells into recipient mice lacking V beta 6, 7, 8.1, and 9 allowed the immune-related paralysis to evolve. Taken together, these results strongly support the hypothesis that T cells expressing rabies SAg-specific V beta 6 T cells, are involved in the genesis of the immunopathology that is characteristic of paralytic rabies.

In vitro non-productive infection of purified natural killer cells by the BRU isolate of the human immunodeficiency virus type 1.

Highly purified natural killer (NK) cell lines and clones, displaying the typical phenotype, morphology and function and obtained from healthy blood donors, were infected in vitro with the BRU isolate of human immunodeficiency virus type 1 (HIV-1). There was no significant increase in reverse transcriptase activity and levels of p24 antigen in the supernatants, but positive staining was observed using an immunogold technique with polyclonal anti-HIV-1 antibodies. When infected NK cells were co-cultivated with autologous non-infected CD4+ mitogen-activated cells, significant levels of reverse transcriptase activity and p24 antigen in supernatants were detected. Giant syncytial cells and a high number of mature virion particles were also evident. When NK cell lines or clones from HIV-1-infected patients were studied, neither the presence of p24 antigen nor reverse transcriptase activity was detected in the supernatants after stimulation with mitogens, cytokines or co-culture with allogeneic CD4+ mitogen-activated cells. PCR studies did not detect HIV-1 genes in freshly purified NK cells, cell lines or clones from infected patients. Taken together these results suggest that (i) normal NK cells can be infected in vitro by the HIV-1 BRU isolate in a non-productive fashion, (ii) PCR with NK cell DNA of HIV-1-infected patients indicates that in vivo few of these cells, if any, are infected by HIV-1 and (iii) the mechanisms responsible for the impairment of NK cell function during HIV-1 infection remain to be determined and are probably not related to a direct cytopathic effect of the virus.

Differential requirements for HIV-1 replication in naive and memory CD4 T cells from asymptomatic HIV-1 seropositive carriers and AIDS patients.

One of the major routes for modulating HIV-1 expression by infected T cells is through the control of transcription initiation from the HIV-1 long terminal repeat (LTR), which is regulated either by its own viral gene products or by several cellular DNA-binding proteins induced during T cell activation. Previous work reported preferential HIV-1 infection and replication of memory CD4 T cells from infected individuals, which was explained either by a higher viral burden of this subset or by differences between naive and memory cells in the activation of the general transcription machinery involved in HIV-1 replication. In this work, we have studied HIV-1 replication by highly purified naive and memory CD4 T cells from asymptomatic seropositive carriers (ASC) and AIDS patients following different activation signals. Our results demonstrate that viral replication in memory cells from ASC was observed after mitogenic (phytohaemagglutinin (PHA) and/or phorbol myristate acetate (PMA)) recombinant tumour necrosis factor-alpha (rTNF-alpha) and CD3-mediated activation. In contrast, in naive subsets, early viral replication was almost exclusively observed upon CD3-mediated activation. AIDS patients are characterized by similar levels of viral replication in both subsets after PHA and soluble or immobilized anti-CD3 MoAb activation. However, naive subsets from AIDS patients still displayed differential requirements since they failed to replicate HIV-1 after treatment with PMA and rTNF-alpha. Taken together, these results provide evidence that HIV-1 replication in CD4+ T cells from infected individuals is a function of the differentiation stage of the cells, the disease stage of the patient and the activation signal employed.

Natural killer (NK) cell activity during HIV infection: a decrease in NK activity is observed at the clonal level and is not restored after in vitro long-term culture of NK cells.

NK cell activity is impaired in HIV-infected patients. The mechanisms behind the altered NK functions are not clear, and conflicting data concerning NK and antibody-dependent cellular cytotoxicity (ADCC) activity have been reported. In order to investigate whether this impairment is also observed at the clonal level and whether it is related to a defect at the target cell binding and/or the post-binding level, we evaluated highly purified NK cell lines and cloned NK cells obtained from 22 HIV-infected patients at different stages of disease and compared them with normal controls for their ability to: (i) kill K-562 and U-937 cell lines using a 51Cr release assay; (ii) bind and kill K-562 and U-937 cells at the single cell binding level; (iii) release NK cytotoxic factor (NKCF), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma); (iv) kill anti-IgM preincubated Daudi cell line (ADCC activity). This study with cloned NK cells or NK cell lines from HIV-infected individuals showed: (i) a decrease in their lytic capability against target cell lines; (ii) a low ability to form conjugates with K-562 and U-937 cell lines with respect to controls; (iii) a decreased ability to kill bound target cells; (iv) low levels of released NKCF, TNF-alpha and IFN-gamma after incubation with U-937 cells. Taken together, these findings suggest that the impaired NK cell function during HIV infection is also observed at the clonal level and is related to defects both at the target and post-binding levels. However, the precise mechanisms remain to be determined. The inability to restore normal NK activity after long-term culture in the presence of high levels of recombinant IL-2 is in agreement with the hypothesis of a 'general anergic process' during HIV infection.