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S Patterson

Publications and source records attributed to S Patterson.

At least 55 records · Page 3Linked to original sources
PubMed1991

Morphology and phenotype of dendritic cells from peripheral blood and their productive and non-productive infection with human immunodeficiency virus type 1.

Immununoelectron microscopy of human peripheral blood mononuclear cells enriched for the presence of antigen-presenting dendritic cells (DC) has revealed two morphologically distinct cell types both expressing DR and DQ major histocompatibility complex (MHC) class II antigens but lacking T, B, natural killer (NK) and monocyte/macrophage markers. The first (type 1) has an irregular surface with numerous projections and shows cytoplasmic vacuoles. The second (type 2) has a paler nucleus showing only a thin rim of dense heterochromatin, large expanses of cytoplasm devoid of organelles, fewer vacuoles and a smooth cell boundary with few processes. In addition a few cells with a morphology similar to veiled cells of the afferent lymphatics (type 3 DC) were observed. Cells with a morphology intermediate between these three types were observed, suggesting that they may represent stages of the veiled cell differentiation pathway. Type 2 and 3 DC were shown by electron microscopy to be susceptible to productive infection with human immunodeficiency virus (HIV), whilst type 1 DC did not support virus growth. Examination of infected DC preparations by in situ hybridization revealed a higher number of DC positive for viral DNA and RNA than for RNA alone. Thus, in addition to productively infected DC, there may be some that are latently infected, contain defective virus genome or replicate virus at a very low level.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Primary proliferative and cytotoxic T-cell responses to HIV induced in vitro by human dendritic cells.

In earlier studies, primary proliferative and cytotoxic T-cell (CTL) responses to influenza virus were produced in vitro by using mouse dendritic cells (DC) pulsed with virus or viral peptide as the stimulus for syngeneic T cells in 20-microliters hanging-drop cultures. We have now adapted this system for producing primary responses with cells from non-immune donors to produce primary proliferative and CTL responses to human immunodeficiency virus I (HIV) and to HIV peptides in vitro using cells from normal human peripheral blood. All donors in this study were laboratory personnel with no history of HIV infection. DC enriched from peripheral blood were exposed to HIV in vitro and small numbers were added to T lymphocytes in 20-microliters hanging drops. Proliferative responses to virus-infected DC were obtained after 3 days in culture. After 6 days, CTL were obtained that killed virus-infected autologous--but not allogeneic--phytohaemagglutinin (PHA)-stimulated blast cells. Proliferative and CTL responses were obtained using cells from 14 random donors expressing a spectrum of major histocompatibility complex (MHC) types but the CTL, once produced, showed killing restricted by the MHC class I type. Treatment of cultures with monoclonal antibody (mAb) to CD4-positive cells at the beginning of culture blocked the development of both proliferative and CTL responses, but treatment after 5 days had no effect on the CTL activity. Treatment with MCA to CD8-positive cells at the beginning of culture did not block proliferation significantly, but treatment either before or after the 5-day culture period blocked CTL responses. Collaboration between proliferating CD4-positive cells and CD8-positive cells may thus be required to produce CTL of the CD8 phenotype. DC exposed to HIV also produced CTL that killed autologous blast cells pulsed with gp120 envelope glycoprotein. However, DC infected with whole virus did not produce CTL that lysed target cells pulsed with a synthetic peptide, which included a known T-cell epitope of gp120 (representing amino acids 111-126). DC pulsed with gp120 were a poor stimulus for the development of CTL. In contrast, DC pulsed with the peptide (111-126) stimulated both proliferative and CTL responses. The latter killed not only target cells pulsed with the peptide itself or with gp120 but also killed virus-infected autologous blast cells. CTL were again obtained reproducibly with this peptide using donors expressing a spectrum of MHC types.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Division↗
PubMed1990

HIV I infection of dendritic cells.

Dendritic cells (DC) from human peripheral blood are susceptible to productive and probably to latent infection with HIV-I. Infection of DC also occurs in vivo since in HIV-seropositive individuals Langerhans' cells of the skin and DC from peripheral blood, (in preparation) are infected. In peripheral blood 3-25% of DC, identified as large, low-density cells lacking monocyte markers, are infected as judged by in situ hybridization with an HIV probe. This contrasts with the lower proportion (< 0.2%) of other cells infected. DC exposed to HIV in vitro or in vivo fail to present other antigens or mitogens to stimulate T cells. This functional defect in infected DC is not blocked by the presence of soluble CD4 antigen and occurs in the absence of T cell infection suggesting a block at the level of the antigen-presenting cell itself. Infection, depletion and dysfunction of DC in HIV seropositive patients is already present in asymptomatic individuals and this precedes the appearance of T cell defects. We speculate that loss of functional DC may be a fundamental defect leading to a block in recruitment of resting T cells into immune responses. In contrast to the HIV-induced impairment of antigen presentation by DC, these cells were potent stimulators of responses to the HIV antigens themselves. Normal DC infected with HIV in vitro stimulated primary proliferative and cytotoxic T cell responses (in preparation). These were produced in cells from individuals expressing a range of different MHC types but the cytotoxic cells, once produced, killed autologous but not allogeneic, infected T cell blasts. Primary response to viral peptides can also be produced suggesting that this system may be useful for identifying immunogenic epitopes of HIV using cells from sero-negative, non-immunocompromised individuals.

CD4 Antigens↗
PubMed1990

Dendritic cell infection, depletion and dysfunction in HIV-infected individuals.

Immune responses in resting T cells are initiated by the presentation of antigen by bone marrow-derived dendritic cells (DC). Normal DC are susceptible to infection with human immunodeficiency virus (HIV) in vitro (Patterson & Knight, 1987) and this blocks their capacity to stimulate T-cell responses to other antigens (Macatonia, Patterson & Knight, 1989a). To study the relationship between HIV and DC in patients and its relevance to the pathogenesis of disease, DC have been isolated from the blood of individuals in the different clinical categories, counted, examined for the presence of virus genome and their antigen-presenting capacity measured. Infection, depletion and impaired function of DC occur in early HIV infection. HIV seropositive patients who were asymptomatic and those with symptoms of disease had significantly reduced numbers of DC, but patients with persistent generalized lymphadenopathy had normal numbers. Between 3% and 21% of DC, identified as large low-density cells not bearing monocyte, lymphocyte or natural killer cell markers, were infected with HIV, as indicated by in situ hybridization. Less than 0.12% of the lymphocytes or monocytes were infected. The DC from infected individuals were poor at enhancing responses to the mitogen concanavalin A (Con A). They also caused low levels of stimulation in allogeneic lymphocytes in mixed leucocyte cultures. By contrast, T cells from asymptomatic patients gave normal T-cell responses to uninfected allogeneic DC, although those from acquired immunodeficiency syndrome (AIDS) patients did show reduced responsiveness. Defects in DC thus precede both the appearance of symptoms and changes in T cells and may be instrumental in the development of AIDS. Furthermore, since DC numbers and function differ at different stages of disease, monitoring these may contribute to clinical assessment and lead to new therapeutic approaches.

Cell Count↗
PubMed1989

Suppression of immune responses by dendritic cells infected with HIV.

Evidence of human immunodeficiency virus (HIV) replication both in the skin Langerhans' cells of AIDS patients (Tschachler et al., 1987) and in normal, peripheral blood dendritic cells (DC) (Patterson & Knight, 1987; Knight & Patterson, 1989) suggests that infection of these antigen-presenting cells may contribute to the immunosuppression seen in AIDS. Support for this hypothesis is now provided by experiments in which the capacity of DC infected in vitro to present mitogen to normal syngeneic lymphocytes was measured. Infecting DC with HIV before culturing with lymphocytes inhibited mitogen-stimulated cell proliferation. Viral DNA was detected in DC in these cultures by in situ hybridization but, in addition, HIV was also present in a small proportion of lymphocytes. However, introducing an inhibitor of virus replication, 2',3' dideoxyadenosine, after infection of the DC but before culturing with lymphocytes, blocked growth of HIV in lymphocytes. In these latter experiments mitogen proliferation responses were still suppressed. Infection of DC could, therefore, cause immunosuppression in AIDS, both by direct effect on antigen-presentation and by the transfer of HIV to T cells.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Infection of B lymphocytes by the human immunodeficiency virus and their susceptibility to cytotoxic cells.

The T4 molecule (CD4) is an important component of the human immunodeficiency virus (HIV) receptor. As yet, no other component has been demonstrated. We report here that two cell lines, a B lymphoblastoid cell line (Gupta) and a glial cell line (HEB) derived from human embryonal brain tissue, are productively infectable with two distinct isolates of HIV as judged by electron microscopy and immunological and virological studies. These two cell lines do not display detectable surface CD4 glycoprotein. However, using S1 nuclease analysis, we have found that both cell lines do express low levels of CD4 mRNA. Neither of them produced syncytia formation upon HIV infection, a recognized feature of HIV-infected cells strongly expressing the CD4 glycoprotein. It is conceivable that the CD4 mRNA is translated, resulting in meager surface expression of CD4 molecules undetectable by conventional techniques. Therefore, infection with HIV may be one of the most sensitive methods of demonstrating low levels of CD4 expression by human cells. Furthermore, HIV-infected Gupta cells have here been shown to be more susceptible to the lytic activity of natural killer (NK) cells than their uninfected counterparts. These phenomena may be important for pathogenesis of HIV-associated disorders.

Antibodies, Monoclonal↗
PubMed1988

The intracellular distribution of influenza virus matrix protein and nucleoprotein in infected cells and their relationship to haemagglutinin in the plasma membrane.

Pre- and post-embedding immune electron microscopy techniques employing ferritin and large and small gold markers to detect cell surface and intracellular antigens respectively, have been combined in a study of influenza virus-infected cells. This has permitted, for the first time, the simultaneous detection of intracellular virus matrix protein (M), nucleoprotein (NP) and membrane haemagglutinin (HA). The technique facilitated an investigation of the possible physical interrelationship between these three proteins both in the infected cell, and on the infected cell membrane. Electron-dense bodies uniformly labelled by antibody to M protein were observed in the nucleus and cytoplasm. Similarly, NP was detected in both the nucleus and cytoplasm. Approximately 50% of the nuclear NP was located in close proximity to the M protein-containing dense bodies but mainly on the perimeter of the structures. A similar relationship of NP to the M-containing dense bodies was observed in the cytoplasm. M protein and NP were readily detected in sections of budding virions. Labelling of these proteins was also observed on the cytoplasmic face of the plasma membrane but the density of labelling only occasionally approached that of newly formed virions. These findings suggest that budding occurs very quickly after the internal proteins arrive at the plasma membrane. Double labelling experiments on the cell surface indicate that NP and HA behave as independent molecules and do not form tight complexes with each other.

Animals↗
PubMed1988

Role of retroviruses in acquired hypogammaglobulinaemia.

Mononuclear cells were obtained from 42 patients with 'common variable' hypogammaglobulinaemia (CVH) and co-cultured with various cell lines in an attempt to isolate retroviruses. Cultures from only two patients showed evidence of a viral infection, although the virus could not be isolated and characterized in either. Despite the previous isolation of HIV's from two other CVH patients, this data suggests that similar viruses are not etiologically involved in the majority of patients.

Adult↗
PubMed1987

L6 skeletal muscle cells have functional V1-vasopressin receptors coupled to stimulated inositol phospholipid metabolism.

The effects of vasopressin and related peptides upon the rat skeletal muscle cell line, L6, have been examined. No effects upon cellular cyclic AMP levels were found indicating that L6 cells possess no functional V2-vasopressin receptors. Vasopressin and its analogues did, however, stimulate the rapid and dose-dependent accumulation of inositol phosphates. This effect and the rank order of potency of vasopressin analogues demonstrate the presence of functional V1-vasopressin receptors upon L6 cells. These results suggest that the L6 line may be a useful model for vasopressin effects upon skeletal muscle metabolism.

Animals↗
PubMed1987

Susceptibility of human peripheral blood dendritic cells to infection by human immunodeficiency virus.

Preparations of human peripheral blood dendritic cells have been infected with human immunodeficiency virus (HIV). After 5 days in culture they were examined by electron microscopy. Virus was observed budding from the plasma membrane of dendritic cells and mature virions were observed on the cell surface. In addition, a second cell type, similar in morphology to 'classical' dendritic cells but containing numerous cytoplasmic granules, was also found to support replication of the virus. We speculate that the growth of HIV in dendritic cells could cause immunosuppression by impairing antigen presentation.

Cytoplasmic Granules↗
PubMed1987

Morphologic analysis of the interactions between lymphocytic choriomeningitis virus-specific cloned cytotoxic T cells and virus infected targets.

The interactions between lymphocytic choriomeningitis virus-specific cloned cytotoxic T lymphocytes (CTL) and virus infected targets have been examined by electron microscopy. CTLs, which were readily differentiated from target cells by the presence of cytoplasmic granular inclusions, made intimate contact with infected cells. Some CTLs contacted infected cells via numerous interdigitating processes; others were observed thrusting finger-like protrusions deep into the target cell; some were seen with their plasma membranes lying closely opposed to that of the infected cell. The majority (55%) of bound CTLs had their Golgi apparatus oriented towards the target cell and 42% of bound CTL had granular inclusions in close proximity to the contact zone. Evidence is presented which suggests that the contents of the granular inclusions are released by CTLs in contact with infected cells. Granules appeared to be released close to the target cell rather than from random sites on the CTL surface. Examination of supernatants from effector-target cell incubation mixtures by negative staining revealed membranes bearing lesions with an internal diameter of approximately 15 nm.

Animals↗
PubMed1986

Isolation of retroviruses from two patients with "common variable" hypogammaglobulinaemia.

Retroviruses related to human T-lymphotropic virus III/lymphadenopathy-associated virus (HTLV-III/LAV) have been isolated from peripheral-blood mononuclear cells of two patients with "common variable" hypogammaglobulinaemia who were being treated with intravenous gammaglobulin. One has had three different opportunistic infections. In both patients hypogammaglobulinaemia developed within 6 years of a longlasting undiagnosed viral-like illness in adolescence, and it is suggested that the virus causing that illness also gave rise to the hypogammaglobulinaemia. However, iatrogenic infection from intravenous gammaglobulin cannot be ruled out.

Adolescent↗
PubMed1986

Analysis of antigenic determinants on internal and external proteins of influenza virus and identification of antigenic subpopulations of virions in recent field isolates using monoclonal antibodies and immunogold labelling.

An electron microscopic immunogold labelling technique employing monoclonal antibodies has been applied to the antigenic analysis of influenza A and B viruses. Reassortant influenza A H3N2 viruses containing haemagglutinin molecules from viruses isolated between 1968 and 1982 were analysed with a panel of monoclonal antibodies raised against viruses which appeared over the same period. The immunogold labelling technique clearly demonstrated the antigenic drift in the haemagglutinin molecule that occurred between 1968 and 1982. When the technique was applied to the examination of viruses from a more geographically restricted influenza epidemic in a semi-closed community, antigenic variants were found. Furthermore the technique enabled the identification of distinct antigenic variant subpopulations within a single clinical isolate. Analysis of the HA of MDCK cell or egg grown virus by this procedure provided data to support the hypothesis that the host cell exerts selective pressure on subpopulations of virus resulting in the emergence of antigenic variants.

Antibodies, Monoclonal↗
PubMed1986

Early interactions between animal viruses and the host cell: relevance to viral vaccines.

Viral recognition of specific receptors in the host cell plasma membrane is the first step in virus infection. Attachment is followed by a redistribution or capping of virus particles on the cell surface which may play a role in the uptake process. Certain viruses penetrate the plasma membrane directly but many, both enveloped and non-enveloped viruses, are endocytosed at coated pits and subsequently pass into endosomes. The low pH environment of the endosome facilitates passage of the viral genome into the cytoplasm. For some viruses the mechanism of membrane penetration is now known to be linked to a pH-mediated conformational change in external virion proteins. As a consequence of infection there are alterations in the permeability of the plasma membrane which may contribute to cellular damage. Recent advances in the understanding of these processes are reviewed and their relevance to the development of new strategies for vaccines emphasised.

Adenoviridae↗
PubMed1985

Relationship between large granular lymphocytes and NK-1.2+ cells from normal and poly(inosinic:cytidylic acid) (poly(I:C]-treated mice.

The present work analyzes the relationship between large granular lymphocytes (LGL), NK-1.2+ cells, and natural killer (NK) activity of C3H/HeN mice. Different hematic cell fractions were obtained according to their nylon-wool adherence and density on Percoll gradients. NK-1.2+ cells (8% of nucleated cells) were more numerous than LGL (3% of nucleated cells) in the input blood population. Eighty-five percent of LGL were recovered from the sorted NK-1.2+ cell fraction. After incubation on nylon-wool column, 63% of LGL and 36% of NK-1.2+ were eluted in the nonadherent fraction. Eighteen percent of NK-1.2+ cells were recovered from the most adherent elutable cell fraction. After the discontinuous Percoll gradient most LGL were present in the low-density fractions while 20% of NK-1.2+ cells were recovered from the highest-density fraction. NK activity was significant both in the nylon-wool-nonadherent and -adherent fractions. After the Percoll gradient most NK activity was present in the low-density fractions. In the present experimental conditions treatment poly(inosinic:cytidylic acid) (poly(I:C] did not increase the numbers of LGL and NK-1.2+ cells either in the blood or in the spleen. However it increased significantly the NK activity of the input cell populations and of the nonadherent and low-density fractions. Similarly, exposure of specific pathogen-free (SPF) mice to non-SPF conditions stimulated NK cytotoxicity but did not alter the percentage of LGL in the blood or in the spleen. Poly(I:C) treatment induced a shift of LGL and NK-1.2+ cells toward the low-density fractions. In poly(I:C)-treated mice images of granule secretion from LGL were detected. Taken together, the present results indicate that LGL and NK-1.2+ cell populations do not totally overlap. Moreover subpopulations of LGL and NK-1.2+ cells can differ in NK activity, morphology, density, adherence to nylon wool, and response to poly(I:C).

Animals↗