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Biomedical subjects

A S Fauci

Publications and source records attributed to A S Fauci.

At least 19 recordsLinked to original sources
PubMed1995

Interleukin 2 induces CD8+ T cell-mediated suppression of human immunodeficiency virus replication in CD4+ T cells and this effect overrides its ability to stimulate virus expression.

The nonlytic suppression of human immunodeficiency virus (HIV) production from infected CD4+ T cells by CD8+ lymphocytes from HIV-infected individuals is one of the most potent host-mediated antiviral activities observed in vitro. We demonstrate that the pleiotropic cytokine interleukin 2 (IL-2), but not IL-12, is a potent inducer of the CD8+ HIV suppressor phenomenon. IL-2 induces HIV expression in peripheral blood or lymph node mononuclear cells from HIV-infected individuals in the absence of CD8+ T cells. However, IL-2 induces CD8+ T cells to suppress HIV expression when added back to these cultures, and this effect dramatically supersedes the ability to IL-2 to induce HIV expression. Five to 25 times fewer CD8+ cells were required to obtain comparable levels of inhibition of viral production if they were activated in the presence of IL-2 as compared with IL-12 or no exogenous cytokine. Furthermore, IL-2 appeared either to induce a qualitative increase in HIV suppressor cell activity or to increase the relative frequency of suppressor cells in the activated (CD25+) CD8+ populations. Analyses of proviral levels in peripheral blood mononuclear cells suggest that CD8+ T cell-mediated lysis of in vivo infected cells is not induced by IL-2. These results have implications for our understanding of the effects of impaired IL-2 production during HIV disease as well as the overall effects of IL-2-based immunotherapy on HIV replication in vivo.

CD4-Positive T-Lymphocytes↗
PubMed1995

Both a precursor and a mature population of dendritic cells can bind HIV. However, only the mature population that expresses CD80 can pass infection to unstimulated CD4+ T cells.

Dendritic cells (DC) are the principle APC involved in primary immune responses; their major function is to obtain Ag in tissues, migrate to lymphoid organs, and activate T cells. DC are also the first immune cells to arrive at sites of inflammation on mucous membranes, the major site of sexual transmission of HIV. We have demonstrated previously that three populations of cells that can develop a dendritic morphology are present in peripheral blood. Two of these populations can express CD83, a marker of DC, and appear to be at different stages of maturation: 1) a precursor population and 2) a mature immunostimulatory DC. Precursor-derived DC express high levels of CD86 (B7-2) and HLA-DR but no CD80 (B7-1), whereas mature DC have high levels of expression of all three markers. Mature DC in peripheral blood bind HIV to their surface and induce infection when added to autologous CD4+ T cells in the absence of added stimuli, such as mitogens. These mature DC, when isolated directly from peripheral blood, appear to be conjugated to T cells, and these conjugates are infected easily and productively with HIV. These findings suggest a role for DC in early HIV infection in which they bind virus and interact with T cells locally or after migrating to a lymphoid organ, thus establishing a productive infection. Furthermore, they likely play a role in the propagation of HIV infection by activating T cells in the presence of HIV, which leads to viral replication and immune cell destruction.

Antigens, CD↗
PubMed1995

IL-10 synergizes with multiple cytokines in enhancing HIV production in cells of monocytic lineage.

Several cytokines, whose expression is increased in human immunodeficiency virus (HIV)-infected individuals, can enhance virus replication in CD4+ T lymphocytes and mononuclear phagocytes (MP). We have previously reported that interleukin (IL)-10 inhibited HIV replication in acutely infected monocyte-derived macrophages (MDM) at concentrations that completely blocked the production of endogenous tumor necrosis factor-alpha (TNF-alpha) and IL-6 from infected cells. In the present study, lower concentrations of IL-10, which were unable to completely suppress endogenous cytokines, paradoxically enhanced HIV replication in MDM induced by other cytokines. This synergistic induction of HIV expression by IL-10 in combination with TNF-alpha, IL-6, and other cytokines was also observed in the chronically infected promonocytic cell line, U1. The enhancing effect of IL-10 was correlated with an increase in HIV mRNA accumulation and potentiation of phorbol ester-induced long terminal repeat-driven transcription that was independent of the NF-kappa B and Sp1 transcription factors. Thus, IL-10 is a cytokine capable of exerting complex regulatory effects on HIV expression in MP as a function of its own concentration and of the presence of other HIV regulatory cytokines.

Blotting, Northern↗
PubMed1995

Analysis of apoptosis in lymph nodes of HIV-infected persons. Intensity of apoptosis correlates with the general state of activation of the lymphoid tissue and not with stage of disease or viral burden.

The occurrence of in vivo apoptosis was investigated in lymph node sections obtained from HIV-infected persons at different stages of disease. The degree of apoptosis in lymph nodes from HIV-infected individuals was compared with that observed in lymph nodes obtained from HIV-negative individuals. Apoptosis was readily detected in lymph nodes obtained from both HIV-negative and HIV-positive persons; however, the degree of apoptosis in lymph nodes obtained from HIV-positive persons was three to four times higher than that observed in the lymph nodes obtained from HIV-negative persons. In contrast to HIV-negative lymph nodes in which apoptosis was confined largely to germinal centers, in HIV-positive lymph nodes all functional compartments of the lymph node (i.e., cortex, paracortex, and sinuses) were extensively involved by this phenomenon. Furthermore, a significant correlation was observed between intensity of apoptosis and degree of activation of the lymphoid tissue associated with HIV infection. In contrast, intensity of apoptosis correlated neither with the clinical stage of HIV disease nor with the viral burden in the lymph node. Finally, apoptosis was not restricted only to CD4+ T cells; both B cells and CD8+ T cells were found to undergo apoptosis. Taken together, these results indicate that the increased intensity of the apoptotic phenomenon in HIV infection is caused by the general state of immune activation, and is independent of the progression of HIV disease and of the levels of viral load.

Acridine Orange↗
PubMed1995

HIV replication in IL-2-stimulated peripheral blood mononuclear cells is driven in an autocrine/paracrine manner by endogenous cytokines.

Replication of HIV is regulated by virus-encoded regulatory proteins, as well as by a variety of cellular factors including cytokines. In the present study, we have investigated the autocrine/paracrine effects of endogenous cytokines on HIV replication in primary PBMCs of healthy HIV seronegative individuals. Addition of rIL-2 to cultures between 0 and 72 h after isolation of PBMCs allowed the replication of primary HIV isolates and laboratory-adapted HIV strains to levels comparable with or greater than those obtained in parallel cultures of autologous PHA-blasts. In this regard, both major cellular targets of HIV infection, CD4+ T lymphocytes and mononuclear phagocytes, were maintained for several weeks in IL-2-stimulated PBMC cultures and virion production was observed in both cell lineages. The kinetics of secretion of several cytokines (such as TNF-alpha, IL-1 beta, IL-6, and IFN-gamma), as well as expression of cellular activation markers, paralleled HIV replication in IL-2-stimulated PBMCs. Endogenous pro-inflammatory cytokines and IFN-gamma played a major role in the regulation of HIV replication in IL-2-stimulated PBMCs, as determined by the ability of several anti-cytokine Abs or antagonists to suppress HIV production; this was not the case in parallel cultures of autologous PHA-blasts. Thus, IL-2-stimulated PBMCs may represent a more physiologic in vitro system than PHA-blasts for the study of HIV infection and replication, and should prove useful in investigating the role of cytokines and other host factors in the regulation of HIV production.

Antibodies, Monoclonal↗
PubMed1995

Three populations of cells with dendritic morphology exist in peripheral blood, only one of which is infectable with human immunodeficiency virus type 1.

Conflicting data have been reported with regard to the infectability, dysfunction, and depletion of dendritic cells (DCs) in human immunodeficiency virus (HIV) disease. These discrepancies could potentially be explained by the existence of multiple subsets of cells with dendritic morphology in peripheral blood. The isolation of DCs in humans is accomplished through negative selection until a morphologically pure population is obtained. Recently, DC precursors purified from peripheral blood by negative selection have been observed to develop into functionally and morphologically mature DCs. In this report we identify three populations of cells in peripheral blood that have or can develop a dendritic morphology. The first population, when allowed to mature in culture, develops a dendritic morphology and gains the expression of HB15, a marker of DCs in blood, thymus, skin, and lymphoid organs. The second population expresses HB15 and has the phenotypic and morphologic characteristics of mature DCs. The third population is morphologically very similar to mature DCs but does not share the same T-cell-stimulatory activity and is the only population that is infectable with HIV. Understanding the heterogeneity of cells of dendritic lineage and/or morphology in the peripheral blood will aid in understanding their role as antigen-presenting cells in general and as potential participants in the immunopathogenesis of HIV disease.

Antigens, Surface↗
PubMed1995

An analysis of forty-two Wegener's granulomatosis patients treated with methotrexate and prednisone.

OBJECTIVE: To determine the efficacy of low-dose methotrexate (MTX) plus prednisone in the treatment of Wegener's granulomatosis (WG). METHODS: An open-label study of weekly low-dose MTX plus prednisone for the treatment of WG was performed. Forty-two patients who did not have immediately life-threatening disease were enrolled into the study. Outcome was determined by clinical characteristics and pathologic, laboratory, and radiographic findings. RESULTS: Weekly administration of MTX and prednisone resulted in remission of disease in 30 of the 42 patients (71%). The median time to remission was 4.2 months. The estimated median time to relapse for all patients in whom remission was achieved was 29 months. Eight patients who had relapses were treated with a second course of MTX plus prednisone, and a second remission was induced in 6 of the 8 (75%). CONCLUSION: Weekly low-dose MTX was shown in this study to be an acceptable alternative form of therapy for selected patients with WG who do not have immediately life-threatening disease or who have developed serious cyclophosphamide-associated toxicity.

Administration, Oral↗
PubMed1995

Effect of anti-V3 antibodies on cell-free and cell-to-cell human immunodeficiency virus transmission.

The present study was undertaken to compare the effects of a type-specific (HIV-1 MN) anti-V3 antibody on in vitro human immunodeficiency virus (HIV) infection of peripheral blood mononuclear cells in systems of cell-free versus cell-to-cell transmission of virus. Anti-V3 antibody completely prevented HIV-1 infection when cell-free virus was the sole mechanism of infection. A significant reduction of the neutralizing activity of the anti-V3 antibody was observed when infectivity was dependent on both cell-free and cell-to-cell mechanisms of infection. Furthermore, when cell-to-cell transfer of virions was the primary mechanism of HIV-1 infection, inhibition of HIV-1 infection was not observed. Therefore, a potent neutralizing antibody with a single epitope specificity failed to effectively control dissemination of a persistent HIV-1 infection in a system characterized predominantly by cell-to-cell transfer of virus.

Amino Acid Sequence↗
PubMed1995

Cross-linking of CD30 induces HIV expression in chronically infected T cells.

CD30, a member of the tumor necrosis factor (TNF) receptor family, is expressed constitutively on the surface of the human T cell line ACH-2, which is chronically infected with human immunodeficiency virus type-1 (HIV)-1. We demonstrate that cross-linking CD30 with an anti-CD30-specific monoclonal antibody, which mimics the described biological activities of the CD30 ligand (CD30L), results in HIV expression. CD30 cross-linking does not alter proliferation of ACH-2 cells and the induction of HIV expression is not mediated by endogenous TNF alpha/beta. Furthermore, cross-linking of CD30 leads to NF-kappa B activation and enhanced HIV transcription. Thus, CD30-CD30L interactions mediate the induction of HIV expression by a kappa B-dependent pathway that is independent of TNF. This mechanism may be important in the activation of HIV expression from latently infected CD4+ T cells, especially in lymphoid organs where cell to cell contact is conducive to receptor-ligand interactions.

Antibodies, Monoclonal↗
PubMed1995

Effect of cellular differentiation on cytokine-induced expression of human immunodeficiency virus in chronically infected promonocytic cells: dissociation of cellular differentiation and viral expression.

Cellular differentiation is thought to play an important role in the susceptibility of monocytic lineage cells to human immunodeficiency virus (HIV) infection as well as in their ability to support virus replication. In addition, virus replication in monocytes/macrophages has been demonstrated in vitro to be strongly modulated by several cytokines such as tumor necrosis factor alpha and granulocyte-macrophage colony-stimulating factor. The purpose of the present study was to investigate the interaction between cellular differentiation and cytokines in the regulation of HIV expression from chronically infected monocytic lineage cells. U1, a persistently HIV-infected promonocytic cell line, is characterized by low levels of virus expression which can be modulated by several cytokines. 1 alpha,-25-Dihydroxyvitamin D3 (Vit.D3), a well-known differentiating agent for myelomonocytic cells which has been previously reported to modulate HIV replication in other in vitro systems, induced maturation of U1 cells toward a macrophage-like phenotype, as demonstrated by the induction of the differentiation-associated cell surface markers CD14 and CD11b. Vit.D3-induced differentiation did not result in induction of HIV expression; however, when U1 cells were stimulated with tumor necrosis factor alpha in the presence of Vit.D3, a synergistic induction of cell differentiation and viral expression was demonstrated. In contrast, Vit.D3 suppressed the induction of HIV expression in U1 cells stimulated with gamma interferon, interleukin-6, and granulocyte-macrophage colony-stimulating factor, although synergy between Vit.D3 and these cytokines was observed in terms of cellular differentiation. These data suggest that differentiation of monocytic cells does not necessarily correlate with increased HIV expression.

Calcitriol↗
PubMed1995

New concepts in the immunopathogenesis of HIV infection.

The typical course of HIV infection is characterized by multiple phases that occur over a period of eight to ten years. A critical event in the initial establishment of HIV infection is the localization of HIV in lymphoid organs that serve as major reservoirs for HIV and as primary sites for virus replication. Despite the fact that the majority of HIV-infected individuals do not show any clinical signs of disease activity for extended periods of time, HIV disease is active and progressive in lymphoid organs during this clinically latent period. Persistence of virus in lymphoid organs causes a chronic stimulation of the immune system that ultimately leads to destruction of the lymphoid tissue and loss of the ability to respond to HIV and/or other pathogens. Major expansions of restricted subsets of CD8+ T cells determined by the usage of certain variable domains (V) of the beta (beta) chain of the T cell receptor (TCR) occur in certain patients during primary HIV infection. These restricted expansions of CD8+ V beta subsets are oligoclonal and represent HIV-specific immune responses with cytolytic T cell activity. Although only limited numbers of patients were studied thus far, certain patterns have emerged that appear to correlate with the subsequent clinical outcome. It is conceivable that immunologic and virologic events associated with primary infection have a major impact on the ultimate course of HIV disease. Histopathologic, virologic, and immunologic studies of long-term nonprogressors (LTNP) indicate that a small proportion of patients who have been HIV-infected for approximately 10 years have normal lymph node architecture, brisk HIV-specific humoral and cellular immune responses, and high and stable CD4+ T cell counts serially determined over years. Viral burden and expression are low in these patients; however, low levels of viremia are present, and virus derived from mononuclear cells is replication competent and infectious in most patients. Studies of events associated with primary HIV infection, examination of lymphoid tissue at various stages of disease, and dissection of the immunologic and virologic components of LTNP should contribute substantially to our understanding of the pathogenesis of HIV disease.

Amino Acid Sequence↗
PubMed1995

Pneumocystis carinii pneumonia: a major complication of immunosuppressive therapy in patients with Wegener's granulomatosis.

The risk factors and clinical and laboratory parameters in Pneumocystis carinii pneumonia in patients with Wegener's granulomatosis have not been well characterized. We undertook a retrospective chart review of all patients with a diagnosis of Wegener's granulomatosis and P. carinii pneumonia who were followed at the National Institute of Allergy and Infectious Diseases of the National Institutes of Health. The chart review focused on clinical, laboratory, and roentgenologic evidence of P. carinii pneumonia. Eleven cases of P. carinii pneumonia were diagnosed in some 180 patients with Wegener's granulomatosis, for an overall incidence of approximately 6%. All patients developed P. carinii pneumonia either during the initial course of treatment or during therapy for recurrent Wegener's granulomatosis. All patients were receiving daily glucocorticoids and a second immunosuppressive therapy. Lymphocytopenia was noted in all patients, with a mean +/- SEM total lymphocyte count of 303 +/- 69 cells/microL. All patients tested (10 of 11) were seronegative for human immunodeficiency virus (HIV) infection. Eight presented with worsening chest roentgenograms compared with baseline, whereas three presented with normal chest roentgenograms. We conclude that P. carinii is a common opportunistic pathogen in patients with Wegener's granulomatosis receiving immunosuppressive therapy. Therapeutic immunosuppression (daily glucocorticoids and immunosuppressive agents) and the resultant lymphocytopenia, as well as the lymphocyte and monocyte functional abnormalities caused by glucocorticoids, may be the most likely factors predisposing to P. carinii pneumonia in patients with Wegener's granulomatosis. Based on our data, all patients with Wegener's granulomatosis should be given chemoprophylaxis against P. carinii while they are receiving daily glucocorticoids.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1995

Cutaneous pathology in Wegener's granulomatosis. A clinicopathologic study of 75 biopsies in 46 patients.

While no cutaneous lesion is specific for Wegener's granulomatosis (WG), several histopathologic entities, including leukocytoclastic vasculitis and necrotizing granulomatous inflammation, are characteristic. This report details the histopathologic features of 75 cutaneous biopsies from 46 patients with WG. Biopsies were subdivided into histologic groups that included leukocytoclastic vasculitis (31%), granulomatous inflammation (GI) (19%), nonspecific ulceration (4%), superficial dermal and epidermal necrosis without inflammation (2.7%), erythema nodosum (2.7%), granuloma annulare (1%), chronic inflammation (31%), and acute inflammatory lesions without vasculitis (9%). No convincing example of granulomatous vasculitis was observed. The histopathologic subgroups were correlated with clinical features, and the results were compared with those from a control group of 82 WG patients with no skin involvement. We found that the histopathologic subgroups of leukocytoclastic vasculitis and granulomatous inflammation correlated with different clinical courses. Patients with leukocytoclastic vasculitis developed WG at an earlier age (median age, 30 years) than did the control group (median age, 45 years). Leukocytoclastic vasculitis developed shortly after onset of WG (median, 15 months vs. 35 months for patients with nonspecific chronic inflammation). All lesions occurred during active disease. Active disease with leukocytoclastic vasculitis was associated with a mean erythrocyte sedimentation rate twice that of active disease in the same patient when leukocytoclastic vasculitis was absent. The patients with leukocytoclastic vasculitis had more rapidly progressive and widespread WG than patients with granulomatous skin lesions or patients without skin lesions. A marked excess of joint and musculoskeletal symptoms and renal disease was seen in patients with leukocytoclastic vasculitis. Patients with granulomatous inflammation also developed WG at an early age (median age, 30 years) when compared with the control group. Cutaneous granulomatous lesions also developed shortly after presentation (median, 12 months). Only 64% of granulomatous biopsies were from patients with active disease. These patients frequently had neither renal nor pulmonary manifestations of WG, and their disease progressed at a slower rate than that of the patients with leukocytoclastic vasculitis. These findings suggest that the cutaneous lesions characteristic of WG may correlate with the activity, distribution, and course of the disease.

Adolescent↗
PubMed1994

A family of serine proteases expressed exclusively in myelo-monocytic cells specifically processes the nuclear factor-kappa B subunit p65 in vitro and may impair human immunodeficiency virus replication in these cells.

Two groups of U937 promonocytic cells were obtained by limiting dilution cloning which differed strikingly in their ability to support human immunodeficiency virus 1 (HIV-1) replication. "Plus" clones replicated the virus efficiently, whereas "minus" clones did not. We examined these clones for differences in nuclear factor (NF)-kappa B activity which might account for the observed phenomenon. Stimulation of plus clones liberated the classical p50-p65 complex from cytoplasmic pools, whereas minus clones produced an apparently novel, faster-migrating complex, as judged by electrophoretic mobility shift assays. It is surprising that the faster-migrating complex was composed also of p50 and p65. However, the p65 subunit was COOH-terminally truncated, as shown by immunoprecipitation. The truncation resulted from limited proteolysis of p65 during cellular extraction which released particular lysosomal serine proteases, such as elastase, cathepsin G, and proteinase 3. These specific proteases are coordinately expressed and were present exclusively in the minus U937 clones, but not in the plus clones, as demonstrated in the case of cathepsin G. In addition, these proteases were detected in certain subclones of THP-1 and HL-60 cells and in primary monocytes, in each case correlating with the truncated from of p65. We demonstrate in vitro cleavage of p65 by purified elastase and cathepsin G. It is possible that particular serine proteases may have inhibiting effects on the replication of HIV-1 in myelo-monocytic cells. The data also demonstrate that special precautions must be taken when making extracts from myelo-monocytic cells.

Animals↗