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S M Crowe

Publications and source records attributed to S M Crowe.

At least 55 records · Page 3Linked to original sources
PubMed1996

Human immunodeficiency virus grown in CD4-expressing cells is associated with CD4.

Using a CD4-capture immunoassay for gp120, several strains of human immunodeficiency virus type 1 (HIV-1) grown in CD4-expressing T lymphoblastoid cells were found to contain little CD4-reactive gp120 (0.3-1.0 ng/ml) relative to virus titre (10(3.2)-10(5.0) TCID50/ml) and p24 antigen (80-1000 ng/ml). The measured CD4-reactive gp120 concentrations of HIV-1 suspensions grown in CD4-negative human neuroblastoma cells were 100- to 10,000-fold greater than those of HIV-1 grown in CD4-positive lymphoblastoid cells, even though both virus suspensions contained abundant viral gp120 as shown by immunoblot assay. It was postulated that CD4 derived from host cells might be associated with virions, concealing the binding domains of gp120. CD4 association with HIV-1 virions grown in CD4-positive cells was demonstrated directly by immunoblot assay of sucrose gradient-purified virus suspensions and by specific co-sedimentation of 125I-labelled OKT4 with virions propagated in CD4-expressing cells. CD4 coating of primary HIV-1 isolates grown in peripheral blood mononuclear cells was also observed. The biological significance of CD4 coating of HIV particles remains to be determined.

CD4 Antigens↗
PubMed1995

HIV-1 infection of human macrophages impairs phagocytosis and killing of Toxoplasma gondii.

The susceptibility of patients with AIDS to certain opportunistic infections is due to defective cell-mediated immunity. The contribution of direct infection of macrophages with HIV-1 to this defect is unknown. To address this issue, we infected normal human monocyte-derived macrophages with a monocytotropic strain of HIV-1 and examined their ability to phagocytose and kill the opportunistic pathogen, Toxoplasma gondii. Phagocytosis of heat-killed T. gondii was reduced in HIV-infected macrophages compared with mock-infected controls. Opsonization of heat-killed T. gondii increased phagocytosis by both mock- and HIV-infected macrophages, but phagocytosis in HIV-infected cultures remained lower than in controls. Internalization of live T. gondii by macrophages was unaffected by HIV infection. Intracellular replication of live T. gondii was enhanced by HIV infection, as shown in four experiments, each using monocyte-derived macrophages from a different donor. Treatment of HIV-infected macrophages with IFN-gamma decreased parasite replication but not to control levels. These findings suggest that infection of macrophages by HIV may be a contributing factor to the reactivation of T. gondii infection in patients with AIDS.

Animals↗
PubMed1995

The kinetics of surface expression of CD11/CD18 integrins and CD54 on monocytes and macrophages.

Cells of the macrophage lineage mediate extremely important normal functions of the immune system. Such functions are in part related to interactions between cell-bound LeuCAMs and their ligands. MoAb staining and flow cytometric analysis were used to follow changes in surface expression of LeuCAMs and the LFA-1 ligand CD54 during maturation of peripheral blood monocytes (BM) in vitro. Surface expression of these molecules increased on BM following isolation, the greatest increase being in CD54 and CD11c. Following an initial increase, there was a reduction in CD11a expression after 2 weeks in culture, this being greater on adherent compared with suspension-maintained cells. Expression of CD11b remained high throughout the culture period. LeuCAM and CD54 expression was further compared on freshly isolated alveolar macrophages (AM) and BM paired donors. A reciprocal relationship was observed between CD11c and CD11b on AM and BM, in that BM expressed higher levels of CD11b than CD11c, whilst the converse was true for AM. CD54 expression was also higher on AM than on BM, whilst there was no significant difference in expression of CD11a on these cells. These data suggest that consistent changes occur in the surface expression of the LeuCAMs and CD54 as monocytes mature into macrophages, which may reflect the specific functions of these cells.

CD11 Antigens↗
PubMed1995

The role of bronchoscopy in the diagnosis and treatment of pulmonary disease in HIV-infected patients.

BACKGROUND: Pulmonary disease is the most common reason for presentation and the major cause of death in HIV-infected patients. There has been an evolution in the optimal approach to the investigation of a pulmonary infiltrate in HIV-infected patients since the introduction of induced sputum for the diagnosis of Pneumocystis carinii pneumonia (PCP). AIMS: To evaluate the usefulness of flexible fibreoptic bronchoscopy (FFB), bronchoalveolar lavage (BAL), transbronchial biopsy (TBB) and bronchial brushings (BB) in the diagnosis of pulmonary disease in HIV-infected patients and to examine the effect of FFB on changes in therapy and survival. METHODS: The histories of all HIV-infected patients referred to Fairfield Hospital for FFB between January 1990 and June 1993 were examined retrospectively. RESULTS: Forty-two FFB were performed on 41 patients (40 male and one female). Definitive diagnoses made at FFB included Kaposi's sarcoma (KS) (n = 9), invasive aspergillosis (n = 5), PCP (n = 4), Mycobacterium avium complex (MAC) pneumonia (n = 2), cytomegalovirus (CMV) pneumonia (n = 1), Cryptococcus neoformans pneumonia (n = 1), microsporidium (n = 1) and Pseudomonas aeruginosa pneumonia (n = 1). TBB and BB did not provide a diagnosis for diseases not seen macroscopically at FFB or diagnosed by BAL. FFB findings altered diagnosis in 21/42 (50%) presentations and changed therapy in 26/42 (62%) cases. CONCLUSIONS: FFB together with BAL altered the working diagnosis and changed therapy in a significant number of patients. TBB and BB should not be routinely performed in all patients as these procedures are of limited value in this setting.

AIDS-Related Opportunistic Infections↗
PubMed1995

Role of macrophages in the pathogenesis of human immunodeficiency virus (HIV) infection.

There are a number of machanisms by which HIV-infected macrophages contribute to the pathogenesis of the Acquired Immunodeficiency Syndrome (AIDS). Macrophage-tropic strains of HIV are present at the time of infection, and persist throughout the course of infection, despite the emergence of T cell tropic quasispecies. As HIV causes chronic infection of macrophages with only minimal cytopathology, these cells can provide an important viral reservoir in HIV-infected persons. Macrophages are more susceptible to HIV infection than freshly isolated monocytes. HIV-infected macrophages can contribute to CD4 T lymphocyte depletion through a gp120-CD4 dependent fusion process with uninfected CD4-expressing T cells. Increasing data support the role of HIV-infected macrophages and microglia in the pathogenesis of HIV-related encephalopathy and AIDS-related dementia through the production of neurotoxins. HIV infection of macrophages in vitro results in impairment of many aspects of their function. Reduced phagocytic capacity for certain opportunistic pathogens, including Toxoplasma gondii and Candida albicans, may be responsible for reactivation of these pathogens in persons with advanced HIV infection, although the mechanisms underlying reactivation of infections and susceptibility to disease from new infections are likely to be multifactorial. Our studies showing defective phagocytosis and killing provide additional information that contribute to our understanding of the pathogenesis of AIDS. Studies of in vitro efficacy of potential antiretroviral therapies should be performed in both primary lymphocyte and monocyte cultures, given the importance of both of these cell populations to HIV pathogenesis and their differing biology.

AIDS Dementia Complex↗
PubMed1995

A simple method for the propagation of cervical lymphocytes.

Local immune function is most likely a key influence in the establishment of human papillomavirus infections and its subsequent disease. Unfortunately, little information is known about local cervical immunity, and even less is known about human papillomavirus immunoreactivity. In addition, studies of local immunoreactivity have been hampered by the technical difficulty in obtaining cervical lymphocytes. The objective of the present study was to develop a simple method for the propagation of cervical lymphocytes from biopsy-size specimens. Cervical tissue was obtained from women undergoing a hysterectomy. Cervical samples measuring approximately 3 by 5 by 2 mm were minced and divided into two portions. One portion was digested by standard digestion methods and density gradient lymphocyte separation. The sample was then immunocharacterized for CD4 and CD8 cells by flow cytometry. The other portion was minced into 1-mm3 sections, and each section was placed into a separate well with tissue culture medium and interleukin-2. Lymphocyte counts and immunophenotypic analysis were performed after 18 to 20 days in culture. After 18 to 20 days in culture, the analysis demonstrated that this method of direct lymphocyte culture from a biopsy specimen yielded approximately 1 x 10(6) to 5 x 10(6) lymphocytes. Immunophenotypic studies of the digested sample at day 0 revealed CD4-to-CD8 ratios of between 0.7:1 and 3.5:1, and at days 18 to 20 they revealed ratios of between 2.3:1 and 98:1. In summary, we developed a simple technique for propagating cervical lymphocytes from small tissue samples for the study of the local immune response. Studies are under way to optimize lymphocyte growth and to preserve CD8 populations.

Adolescent↗
PubMed1995

In vitro growth of the microsporidian Septata intestinalis from an AIDS patient with disseminated illness.

A new species of microsporidian, Septata intestinalis, was recently recognized as an opportunistic pathogen of AIDS patients. In this study, it was cultured from the nasopharyngeal aspirate of a human immunodeficiency virus type 1-infected patient with disseminated microsporidiosis. In human embryonic lung cells exposed to S. intestinalis, a cytopathic effect appeared within 28 days as foci of rounded up cells. Thin-section electron microscopy showed a variety of developmental stages of the microsporidium within parasitophorous vacuoles. In monocyte-derived macrophages, evidence of infection and development of the parasite was demonstrated by light and electron microscopy. In both infected human embryonic lung cells and monocyte-derived macrophages, a network of septa separated individual spores. Partial sequencing of the RNA small-subunit gene (16S rDNA gene) confirmed the identity of this parasite as S. intestinalis. This is the first report of the isolation of S. intestinalis in vitro and provides evidence that the parasite can be disseminated by macrophages.

AIDS-Related Opportunistic Infections↗
PubMed1994

Lymphocyte subset analysis by Boolean algebra: a phenotypic approach using a cocktail of 5 antibodies and 3 color immunofluorescence.

Commercial reagent kits for the evaluation of leukocyte subsets involve the staining of a panel of up to six tubes using combinations of pre-mixed fluorescein isothiocyanate (FITC) and R-phycoerythrin (PE) conjugated monoclonal antibodies. We describe a rapid method whereby total CD3+ T-cells, CD4+ T-cells (CD3+ CD4+), CD8+ T-cells (CD3+ CD8+), putative gamma delta-receptor-T-cells (CD3+ CD4- CD8-), and T-cells that are CD3+ CD4+ CD8+ as well as B-lymphocytes and NK-cells can be enumerated after staining in a single tube. Whole blood specimens are labelled with a mixture of antibodies: FITC-conjugated antibodies to CD4 and CD19, PE-conjugated antibodies to CD8 and CD16, and either peridinin chlorophyll protein (PerCP) or allophycocyanin (APC) labelling for antibodies to CD3. After recording 20,000 events the data were analysed on the Consort 32 computer system and LYSYS-II (Becton Dickinson, San Jose, CA) and all of the lymphocyte subset values were determined by Boolean algebra using a technique we refer to as Boolean gate analysis (BGA). Our study has shown that BGA is statistically equivalent to SimulSET lymphocyte subset analysis. Furthermore, the procedure reduces the number of tubes required to two with consequential saving in reagents, consumables, and time.

Antibodies, Monoclonal↗
PubMed1994

Susceptibility of dendritic cells to HIV-1 infection in vitro.

We review recent work on the extent of HIV-1 infection of dendritic cells (DCs) and the consequences of exposure to virus. The reported levels of infection of DCs from blood have varied from "explosive" to "undetectable." The only study that used sorted DCs demonstrated little if any infectability, which may not be surprising given the very low levels of CD4 on the populations that were studied. HIV-1-pulsed, highly purified DCs function as potent antigen-presenting cells during the mixed leukocyte reaction and responses to superantigens. At the same time that the HIV-1-pulsed DCs stimulate CD4+ T cells in DC-T clusters, the virus is transferred to the responding lymphocytes and a vigorous productive infection of the T cells takes place. This pool of transferable HIV-1 is short lived in cultured human blood DCs and likely reflects the capacity of these cells to internalize and recycle vesicles in the endocytic pathway, as revealed with experiments using 0.1-micron fluorescent latex beads. Current efforts are directed to analyzing the interaction of HIV-1 with several populations of DCs that express higher levels of CD4. These include DCs studied in fresh, uncultured blood, as well as skin, thymus, and tonsil DCs. In each case, entry and reverse transcription of HIV-1 are seen, but again, coculture with T cells is required for a productive infection to take place. We conclude that DCs could play a critical role in the pathogenesis of HIV-1 infection, but that the interaction with CD4+ T cells is a critical variable in analyzing the extent of productive infection and its consequences.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Accumulation of unintegrated circular viral DNA in monocytes and growth-arrested T cells following infection with HIV-1.

Cytocidal retrovirus infection is characterized by rapid accumulation of unintegrated viral DNA forms. These are thought to be generated by multiple rounds of reinfection and have been suggested to play a central role in cytopathogenesis. Here we have reviewed the work done in this area with HIV-1, mostly using acutely and chronically infected T cell and monocytic cell lines and in some cases T cells blocked at S phase of the cell cycle by aphidicolin treatment. To these studies, we have compared our findings with HIV-1 infected primary peripheral blood monocyte-derived macrophages and untreated and growth-arrested MT-2 cells, two biologically disparate cell populations. Using 1- and 2-long terminal repeat (LTR) circular forms as indicators of unintegrated viral DNA, we found similar rapid accumulation in both untreated and growth-arrested MT-2 cells. In contrast, we found much lower levels in monocyte/macrophages. Our findings suggest that accumulation of unintegrated viral DNA does not require virus production and reinfection in growth-arrested T cells. The significantly lower levels found in monocyte/macrophages may reflect superinfection resistance, allowing the maintenance of a persistent infection.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Expression of CD11/CD18 and ICAM-1 on monocytes and lymphocytes of HIV-1-infected individuals.

The role of the leukocyte integrins in the infection of cells by HIV-1 or in the progression of AIDS-related disease is of continuing interest. Using a dual-labeling flow cytometric method, we determined the level of expression of the leukocyte integrins and intercellular adhesion molecule 1 (ICAM-1) on monocytes and lymphocytes from HIV-1-infected and uninfected individuals. The mean fluorescence of CD18 on lymphocytes and CD11c on monocytes of HIV-1-infected subjects was significantly higher than for the control group (P = .008 and .014, respectively). There was a trend toward higher fluorescence of CD11a on lymphocytes from HIV-1-infected subjects compared with cells from the control group (P = .089). Integrin expression on lymphocytes or monocytes from HIV-infected individuals did not correlate with their CD4 lymphocyte number. However, the mean fluorescence associated with ICAM-1 on monocytes and CD11a and CD18 expression on lymphocytes was related to clinical stage of disease.

Acquired Immunodeficiency Syndrome↗
PubMed1994

HIV infection of monocyte-derived macrophages in vitro reduces phagocytosis of Candida albicans.

HIV-1 infection of peripheral blood monocyte-derived macrophages (MDMs) is unrelated to the level of CD4 expression on the surface of the cell, is associated with considerable donor variability, causes minimal cytopathology, and results in peak viral antigen production after 2 weeks of infection. Phagocytosis of opsonized Candida albicans by MDMs infected in vitro with several strains of HIV was compared with that of uninfected cells from the same donors; the proportion of MDMs containing the fluorescein isothiocyanate-labeled yeast was determined by flow cytometry and phase contrast microscopy. The intracellular localization of C. albicans was confirmed by confocal microscopy. Using paired MDMs from nine donors, 81% of uninfected and 53% of HIV-infected MDMs phagocytosed C. albicans. In addition, the number of yeast per cell was significantly higher in uninfected MDMs than in HIV-infected cells (mean 6.1 versus 2.5). These findings may partially explain the high incidence of mucocutaneous candidiasis in HIV-infected patients with advanced disease.

AIDS-Related Opportunistic Infections↗
PubMed1994

HIV replication in chronically infected macrophages is not inhibited by the Tat inhibitors Ro-5-3335 and Ro-24-7429.

Human immunodeficiency virus infects different cell types including CD4+ lymphocytes and monocyte-derived macrophages (MDMs). We have examined the activity of the HIV-1 Tat inhibitors Ro-5-3335 and Ro-24-7429 in cultured human peripheral MDMs. Monocytes were isolated from HIV-seronegative donors by gradient centrifugation and plastic adherence. MDMs and unfractionated peripheral blood mononuclear cells (PBMCs) were infected with HIV Ba-L and then treated with drug either immediately (acute infection) or after 4 days (PBMCs) or 14 days (MDMs) (chronic infection). Inhibition of HIV replication by each drug was assessed by quantitation of HIV p24 antigen in culture supernatant using an enzyme immunoassay. In acutely infected MDMs, Ro-5-3335 (10 microM) and Ro-24-7429 (10 microM) resulted in 77% and 99% mean inhibition, respectively, of HIV replication with a clear dose response at lower concentrations; chronically infected MDMs were much less susceptible to these drugs, with both compounds inhibiting p24 antigen production by less than 50% at 10 microM. The drugs had no deleterious effect on cell viability at any concentration tested. In acutely infected PBMCs Ro-5-3335 and Ro-24-7429 resulted in 68% and 68.5% mean inhibition at 10 microM; when the compounds were added 4 days after infection inhibition was less than 50% compared with controls. Thus, the Tat inhibitors were effective in inhibiting acute HIV infection in MDMs but not in chronically infected cells, findings that differ from those of published studies using continuous lymphoblastoid cell lines.

Antigens, Viral↗
PubMed1994

HIV-1 infection of monocyte-derived macrophages reduces Fc and complement receptor expression.

Fc receptor (FcR) and complement receptor (CR) expression on HIV-infected monocyte-derived macrophages may be an important determinant of immune function. We studied the effects of HIV-1 infection of macrophages in vitro on FcR and CR expression. Macrophages were infected with HIV-1DV 7 days following isolation, and the expression of Fc gamma RI-III and CR3 were measured at intervals thereafter by flow cytometry. We found a reduction in receptor expression with the percentage of cells expressing FcRI 14 days post infection declining from 77% to 13%, FcRII fell from 96% to 85%, FcRIII from 45% to 9%, and CR3 from 91% to 67% 14 days following infection. As these receptors are important for macrophage function, their down-modulation may contribute to the pathogenesis of HIV-related disease.

Cell Adhesion Molecules↗
PubMed1994

Anti-nuclear, anti-neutrophil cytoplasmic and anti-glomerular basement membrane antibodies in HIV-infected individuals.

Many autoantibodies have been described in HIV-infected individuals. We have examined the incidence, associations and prognostic significance of anti-nuclear antibodies (ANA), anti-neutrophil cytoplasmic antibodies (ANCA) and anti-glomerular basement membrane (GBM) antibodies in individuals with HIV infections. One hundred and five patients, with asymptomatic infections (n = 37), AIDS-related complex (n = 32) or AIDS (n = 36) were studied. Plasma from 24 of these (23%) were positive for ANA: most demonstrated speckled fluorescence (n = 21) and were of low titre (1+ in 18). ANCA were demonstrated by IIF in 18 individuals (17%) and all fluorescent patterns were seen; 6 of these plasma were also positive in the ELISAs for antibodies to proteinase 3, myeloperoxidase or elastase. Thirteen plasma were positive for ANCA in the neutrophil cytoplasm ELISA; 10 of these were also positive in the specific ELISAs. A total of 30 plasma bound to proteinase 3, myeloperoxidase or elastase in specific ELISAs, in 6 cases with 2 specificities. Finally, 18 plasma (17%) contained anti-GBM antibodies by ELISA, but none of 4 plasma tested in inhibition assays was specific. ANA, ANCA and anti-GBM antibodies were not uncommon in HIV-infected individuals but the presence of these antibodies was not associated with the clinical manifestations of the corresponding autoimmune diseases. In addition, there was no correlation between the demonstration of these antibodies and the immunological status of the individual (apart from a correlation between CD4 counts less than 400/microliters with anti-GBM antibodies), the presence of an opportunistic infection, the development of malignancy or reduced survival. Some of these antibodies may arise from polyclonal activation, or be due to "sticky" serum since we have shown that the presence of anti-GBM antibodies correlated with the demonstration of ANCA by ELISA. These antibodies are not more common in hypergammaglobulinemic plasma but some may be due to heat-treatment of the plasma. The clinician caring for HIV-infected individuals needs to be aware of these "false-positive" antibody results.

Adult↗
PubMed1994

AIDS pathogenesis.

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Acquired Immunodeficiency Syndrome↗