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Biomedical subjects

R J Murray

Publications and source records attributed to R J Murray.

At least 37 records · Page 2Linked to original sources
PubMed1992

Immune escape by Epstein-Barr virus (EBV) carrying Burkitt's lymphoma: in vitro reconstitution of sensitivity to EBV-specific cytotoxic T cells.

Epstein-Barr virus (EBV) positive Burkitt's lymphoma (BL) cells are markedly less sensitive to EBV-specific cytotoxic T cell (CTL) recognition than EBV-transformed lymphoblastoid cell lines of normal B cell origin. Three features of the BL cell phenotype might contribute to this reduced susceptibility: (i) low expression of cell adhesion molecules, (ii) low expression of HLA class I and selective down-regulation of particular alleles, and (iii) down-regulation of all transformation-associated EBV antigens except EBV-encoded nuclear antigen (EBNA)-1. This study assesses the individual importance of each of these features for immune escape. For this purpose the WW1-BL cell line was used which expresses all the known transformation-associated EBV antigens (EBNA-1 to -6 and latent membrane protein-1 and -2) but which is negative for HLA A11 and for the adhesion molecule leukocyte function associated antigen-3 (LFA-3). Using recombinant vectors, these deficiencies have been sequentially corrected and the cells have been tested for sensitivity to EBV (B95.8 strain)-induced CTL preparations recognizing epitope(s) of EBNA-4 in the context of HLA A11. Expression of HLA A11 alone or in combination with LFA-3 did not sensitize WW1-BL cells to these effectors. Lysis was only achieved when HLA A11 was co-expressed with the B95.8 virus-encoded EBNA-4 protein, and in these circumstances sensitization did not require LFA-3. These results indicate that reconstitution of the relevant HLA-EBV epitope target complex on the cell membrane is sufficient to render BL cells sensitive to virus-specific cytolysis. The requirement for EBNA-4 reconstitution to achieve lysis of the WW1-BL/A11 transfectant suggested that the resident WW1 virus-encoded EBNA-4 protein did not contain the relevant target epitope for HLA A11-restricted recognition. This was confirmed by transferring the WW1 virus isolate into another A11-positive B cell background.

Antigens, CD↗
PubMed1992

T cell recognition of Epstein-Barr virus associated lymphomas.

Epstein-Barr virus, a lymphotropic herpesvirus of humans, has potent B cell growth transforming activity yet persists in the lymphoid tissues of most individuals as a lifelong asymptomatic infection. Virus induced B cell growth transformation in vitro is associated with the expression of a limited set of viral genes encoding six nuclear antigens (EBNA 1, 2, 3A, 3B, 3C and LP) and two latent membrane proteins (LMP 1, 2). Healthy virus carriers possess strong EBV specific CTL memory that can be reactivated in vitro. Here, we summarize experiments in which the antigenic specificities of these HLA class I restricted memory CTL responses have been mapped in a range of individuals with different HLA backgrounds. Of the known EBV latent proteins, EBNA 3A, 3B and 3C are frequently the dominant targets for such responses, but examples of responses directed against epitopes of EBNA 2, EBNA-LP or the LMP have been identified; by contrast, CTL responses against epitopes of EBNA 1 have not been observed. Epstein-Barr virus is associated with at least three malignancies of lymphoid origin--immunoblastic lymphomas of the immunosuppressed, endemic Burkitt's lymphoma and a subset of Hodgkin's disease. The immunoblastic lymphomas express the complete spectrum of EBV coded latent proteins and a cellular phenotype similar to that of in vitro transformed B lymphoblastoid cell lines; accordingly, they remain sensitive to EBV specific CTL recognition. Endemic BL cells are not recognized by such CTL, and at least three consistent features of this tumour could contribute to immune escape: (a) allele specific downregulation of HLA class I antigen expression, (b) absence/low expression of cellular adhesion molecules and (c) restriction of EBV latent protein expression to EBNA 1 only. The relative importance of these three features of the BL cell phenotype with regard to sensitivity to CTL recognition is re-interpreted in the light of recent results. Finally, the pattern of virus latent protein expression in EBV positive Hodgkin's disease is described, and the possibility of EBV specific CTL control against this tumour is discussed.

Antigens, Viral↗
PubMed1991

Electrophysiologic effects of FPL 13210 on canine Purkinje fiber action potential duration and Vmax comparison to disopyramide.

The frequency-dependent effects of FPL 13210, a new disopyramide derivative, were examined in isolated canine cardiac Purkinje fibers paced at a frequency of 2 Hz and following abrupt changes in pacing cycle length. At 2 Hz, FPL 13210 depressed Vmax, while shortening action potential duration measured at 50% of repolarization (APD50) and not affecting duration measured at 90% of repolarization (APD90). These effects were concentration dependent over the range of 1-30 microM. The depression of Vmax produced by 5 microM FPL 13210 was not significantly different than that produced by 18 microM disopyramide while the preparations were paced constantly at 2 Hz. At these concentrations, recovery of Vmax was slowed by both FPL 13210 and disopyramide. The slow time constant estimated for this relation after exposure to FPL 13210 was approximately 6.5 times longer than that estimated following administration of disopyramide. In addition, APD90s evoked by early premature stimuli in the presence of 5 microM FPL 13210 were longer than those produced in the absence of drug when the diastolic intervals longer than 100 ms produced shorter APD90s after FPL 13210 administration. Therefore, when FPL 13210 is compared to disopyramide using concentrations selected to produce equivalent degrees of Vmax depression, FPL 13210 produced effects on APD90 that were opposite to those produced by disopyramide when the diastolic interval was longer than normal. These effects of FPL 13210 would suggest that this compound should be classified as a class Ic antiarrhythmic agent, unlike disopyramide, a class Ia antiarrhythmic agent.

Action Potentials↗
PubMed1990

Cross-recognition of a mouse H-2-peptide complex by human HLA-restricted cytotoxic T cells.

Epstein-Barr virus (EBV)-specific human cytotoxic T lymphocyte (CTL) lines from a virus-immune HLA-A11+ donor CMc produced significant lysis of transfected mouse P815 target cells (H-2d background) expressing an introduced HLA-A11 heavy chain gene and the EBV gene encoding latent membrane protein (LMP). To identify the target epitope being recognized, HLA-A11+ transfectants of P815/A11) were pre-exposed to synthetic peptides corresponding to fragments of the LMP sequence and the cells then tested for lysis by CMc effectors; untransfected P815 parent cells were included in these assays as control recipients of the same peptides. Unexpectedly, we identified a peptide preparation (corresponding to LMP residues 124-137) which specifically sensitized not only P815/A11 cells but also the parental P815 cells to lysis. Four independent anti-EBV CTL lines derived from donor CMc gave the same result and single-cell cloning confirmed that lysis was mediated by a subset of the HLA-A11-restricted EBV-specific CTL clones which dominate CMc effector populations. Two lines of evidence indicated that peptide presentation to the human CTL was occurring through H-2Kd molecules on the surface of P815/A11 and P815 cells: (a) a monoclonal antibody reactive with H-2Kd specifically blocked the lysis of both P815/A11 and P815 peptide-treated targets, and (b) on an extended target cell panel, peptide-mediated sensitization was also obtained with a second H-2d mouse line A20.2J and with an H-2Kd transfectant of the H-2k line R1E. This work has therefore identified EBV-specific HLA-A11-restricted human CTL which show fortuitous cross-recognition of a synthetic peptide in the context of a mouse H-2Kd molecule. Such potential for xenogeneic cross-reactivity needs to be borne in mind in situations where the target specificity of human CTL is being analyzed on HLA gene-transfected murine target lines.

Amino Acid Sequence↗
PubMed1990

Effect of oxamisole on immune parameters of mice infected with murine hepatitis.

The effects of Oxamisole, 2,3,5,6,7,8-hexahydro-2-phenyl-8,8- dimethoxyimidazo[1,2a]pyridine on immune parameters of mice infected with murine hepatitis were investigated. Young Swiss Webster mice were injected intraperitoneally (i.p.) with the Friend-Braunsteiner strain of murine hepatitis virus and with various doses of Oxamisole at 48 h pre- 24 h pre-, and 4 h post-virus exposure. Antiviral activity was seen in the drug-treated mice which was approximated on the basis of 21-day survival frequency and hepatic discoloration, SGOT and SGPT levels and amount of infectious virus recoverable from the liver. On day 4 post-viral exposure, splenic cells from some of the drug- and placebo-treated cells of infected mice injected with Oxamisole, 25 mg/kg/day, produced significantly more interleukin-1 and interleukin-2 than cells of infected mice treated with saline only. Similarly, mice treated with 25 mg/kg/day of this compound had cells with significantly increased antibody-dependent cell-mediated cytotoxicity as compared with placebo treated animals. However, cells from mice treated with Oxamisole did not demonstrate altered natural killer cell activity. It is concluded that Oxamisole, when administered to mice infected with murine hepatitis virus, has antiviral properties which possibly are mediated through the immunomodulatory effects of this compound on the immune system.

Adjuvants, Immunologic↗
PubMed1990

Human cytotoxic T-cell responses against Epstein-Barr virus nuclear antigens demonstrated by using recombinant vaccinia viruses.

The potentially pathogenic effects of infection with Epstein-Barr virus (EBV), a B-lymphotropic agent with cell growth-transforming potential, are contained in healthy virus carriers by virus-specific cytotoxic T-lymphocyte (CTL) surveillance. The target antigens against which such CTL responses are directed are yet undefined, but the antigens probably derived from one or more of the EBV "latent" proteins constitutively expressed in virus-transformed B cells. We have analyzed target specificity of CTL responses from two EBV-immune donors that are preferentially reactive against autologous cells transformed with type A but not with type B virus isolates. Coding sequences for four EBV latent proteins with allelic polymorphism between A and B virus types--namely, the EBV nuclear antigens (EBNAs) EBNA 2, EBNA 3a, EBNA 3c, and EBNA leader protein--have been introduced into vaccinia virus vectors under control of vaccinia promoter P7.5 and used to express relevant EBNA proteins in appropriate target cells. Thus the CTL response from one donor has been mapped to type A EBNA 2 protein and from a second donor to type A EBNA 3a protein. Thereafter, a series of recombinant vaccinia viruses were constructed that carried specific internal deletions within the EBNA 2 type A coding sequence; by using these vectors, the above EBNA 2 type A-specific CTL response was shown to be directed against an epitope within a 100-amino acid fragment near the N terminus of the protein. This work clearly shows human CTL recognition of virus-coded nuclear antigens in the EBV system; moreover, it establishes an experimental approach that can be extended to all EBV latent proteins and to the more common CTL responses that cross-react against type A and type B virus isolates.

Antigens, Viral↗
PubMed1989

Pulmonary artery medial hypertrophy in cocaine users without foreign particle microembolization.

A reduction in the DCO has been reported among "free-base" cocaine smokers. We reviewed the pulmonary histopathology in 20 deaths due to cocaine intoxication for either parenchymal or vascular abnormalities which might explain this physiologic finding. Pulmonary artery medical hypertrophy in the absence of foreign particle microembolization was present in four of 20 cases (20 percent). Hemosiderin-laden macrophages were found in seven of 20 cases (35 percent). These abnormalities were not seen in a matched control group. We conclude that in the absence of foreign particle microembolization, pulmonary artery medial hypertrophy occurs among cocaine users, although the mechanism of these vascular changes is unknown. In addition, occult alveolar hemorrhage occurs more frequently among cocaine users than is clinically recognized.

Adult↗
PubMed1988

Downregulation of cell adhesion molecules LFA-3 and ICAM-1 in Epstein-Barr virus-positive Burkitt's lymphoma underlies tumor cell escape from virus-specific T cell surveillance.

Some EBV+ BL cell lines continue to grow as single cells on in vitro passage, show an unusually restricted expression of EBV-latent genes and retain a BL biopsy-like cell surface phenotype (group I/II lines); others change to growth in aggregates, show a broader pattern of virus latent gene expression, and develop a cell surface phenotype more characteristic of EBV-transformed LCL (group III lines). Here we show that the cell surface adhesion molecules LFA-1, ICAM-1, and LFA-3 are expressed at very low levels, if at all, on group I/II lines and are coordinately upregulated as BL lines move towards group III. The change to growth in aggregates reflects the increasing availability of LFA-1 and ICAM-1, the two ligands whose mutual interaction underlies homotypic BL cell adhesion in vitro. The low levels of ICAM-1 and LFA-3 on group I/II BL cell lines are also associated with an impaired ability to interact with EBV-specific CTL in the antigen-independent phase of effector/target conjugation. mAb blocking studies show that the small number of conjugates that are formed with group I/II BL targets involve the LFA-1/ICAM-1 adhesion pathway but not the LFA-3 pathway; in contrast, both pathways contribute to the efficient conjugate formation shown by group III BL or LCL targets. Earlier work identified one group III line, WW1 BL, as unusual since is expressed the full spectrum of EBV-latent proteins yet remained insensitive to lysis by EBV-specific CTL. Here we show that this line has an anomalous pattern of adhesion molecule expression with high levels of LFA-1 and ICAM-1 in the absence of detectable LFA-3. The WW1 BL cells form conjugates with EBV-specific CTL through the LFA-1/ICAM-1 pathway, but in the absence of a target LFA-3/effector CD2 interaction these conjugates do not achieve target cell lysis. This may reflect an important role for target LFA-3 molecules in activating EBV-specific CTL function. From these in vitro studies, we postulate that downregulation of the adhesion molecules LFA-3 and ICAM-1 on EBV+ BL underlies the ability of the malignant clone to evade EBV-specific T cell surveillance in vivo.

Antibodies, Monoclonal↗
PubMed1988

The immunological profile of a new immunomodulatory agent, oxamisole.

Oxamisole is a T-cell immunorestorative agent when administered by the oral (p.o.) route. It has little or no effect on the IgM or IgG responses to the T-dependent antigen, sheep erythrocytes (SRBC), in normal mice but augments antibody production in immunodeficient animals. Unlike the response to SRBC, the humoral immunocompetence of both normal and immunosuppressed animals sensitized with the T-independent antigen, trinitrophenyl-lipopolysaccharide (TNP-LPS) was unaffected by oxamisole. Oxamisole restored cellular immunocompetence, as evidenced by an increase in the in vitro proliferative response of normal murine splenocytes to T-cell mitogens, while decreasing B-cell mitogenic responses. This indicates that oxamisole may selectively restore T-cell function. However, oxamisole did not significantly modify the classical T-cell-mediated delayed hypersensitivity responses to either the protein antigen methylated bovine serum albumin or to the contact-sensitizing antigen oxazolone. When assayed in vitro, oxamisole enhanced macrophage chemotactic function but not phagocytic function, suggesting a potential stimulation of the reticuloendothelial system. In vivo studies failed to demonstrate any consistent significant activation of murine macrophage function following oral dosing with oxamisole.

Adjuvants, Immunologic↗
PubMed1988

Epstein-Barr virus-specific cytotoxic T-cell recognition of transfectants expressing the virus-coded latent membrane protein LMP.

Cytotoxic T cells from Epstein-Barr virus (EBV)-immune individuals specifically kill EBV-transformed B cells from HLA class I antigen-matched donors even though the latently infected cells express only a restricted set of virus genes. The virus-induced target antigens recognized by these immune T cells have not been identified. In our experiments, EBV DNA sequences encoding the virus latent gene products Epstein-Barr nuclear antigen (EBNA)1, EBNA 2, and EBNA-LP and the latent membrane protein (LMP) were individually expressed in a virus-negative human B-lymphoma cell line, Louckes. Transfected clones expressing LMP were killed by EBV-specific cytotoxic T-cell preparations from each of three virus-immune donors HLA matched with Louckes through HLA-A2, B44 antigens; control transfectants or clones expressing one of the EBNA proteins were not recognized. Expression of LMP in a second virus-negative B-cell line, BL41, sensitized these cells to EBV-specific cytolysis restricted through the HLA-A11 antigen. To distinguish between the viral protein and an induced human B-cell activation antigen as the target for T-cell recognition, LMP was then expressed in a murine mastocytoma cell line, P815-A11-restricted human T cells. The LMP-expressing P815-A11 transfectants were susceptible to lysis by EBV-specific cytotoxic T cells from three HLA-A11-positive individuals. Both Louckes and P815-A11 cells were also transfected with constructs capable of encoding a truncated form of LMP (Tr-LMP) which lacks the N-terminal 128 amino acids of the full-length protein. Tr-LMP-expressing transfectants were not recognized by the above T-cell preparations. The results suggest that LMP, and, in particular, epitopes derived from the N-terminal region of the protein, provides one of the target antigens for the EBV-induced human cytotoxic T-cell response.

Animals↗
PubMed1988

Different patterns of Epstein-Barr virus gene expression and of cytotoxic T-cell recognition in B-cell lines infected with transforming (B95.8) or nontransforming (P3HR1) virus strains.

Epstein-Barr virus (EBV)-negative Burkitt's lymphoma (BL) cell lines have been converted to EBV genome positivity by in vitro infection with the transforming EBV strain B95.8 and with the nontransforming mutant strain P3HR1, which has a deletion in the gene encoding the nuclear antigen EBNA2. These B95.8- and P3HR1-converted lines have been compared for their patterns of expression of EBV latent genes (i.e., those viral genes constitutively expressed in all EBV-transformed lines of normal B-cell origin) and for their recognition by EBV-specific cytotoxic T lymphocytes (CTLs), in an effort to identify which latent gene products provide target antigens for the T-cell response. B95.8-converted lines on several different EBV-negative BL-cell backgrounds all showed detectable expression of the nuclear antigens EBNA1, EBNA2, and EBNA3 and of the latent membrane protein (LMP); such converts were also clearly recognized by EBV-specific CTL preparations with restriction through selected human leukocyte antigen (HLA) class I antigens on the target cell surface. The corresponding P3HR1-converted lines (lacking an EBNA2 gene) expressed EBNA1 and EBNA3 but, surprisingly, showed no detectable LMP; furthermore, these converts were not recognized by EBV-specific CTLs. Such differences in T-cell recognition were not due to any differences in expression of the relevant HLA-restricting determinants between the two types of convert, as shown by binding of specific monoclonal antibodies and by the susceptibility of both B95.8 and P3HR1 converts to allospecific CTLs directed against these same HLA molecules. The results suggest that in the normal infectious cycle, EBNA2 may be required for subsequent expression of LMP and that both EBNA2 and LMP (but not EBNA1 or EBNA3) may provide target antigens for the EBV-specific T-cell response.

Antigens, Viral↗
PubMed1988

Diffuse alveolar hemorrhage temporally related to cocaine smoking.

Previous reports of respiratory complications from cocaine abuse have focused on pulmonary barotrauma or a reduction in carbon monoxide diffusing capacity. We report a patient who developed life-threatening alveolar hemorrhage following repeated inhalation of alkaloid cocaine.

Adult↗
PubMed1988

Recovery from cryptococcemia and the adult respiratory distress syndrome in the acquired immunodeficiency syndrome.

We describe a patient who presented with cryptococcosis and the adult respiratory distress syndrome (ARDS) as the initial manifestation of the acquired immunodeficiency syndrome. This patient represents the first reported recovery from ARDS secondary to widespread cryptococcosis. He is currently doing well as an outpatient on maintenance therapy with amphotericin B and azidothymidine.

Acquired Immunodeficiency Syndrome↗
PubMed1987

PR 879-317A enhances in vitro immune activity of peripheral blood mononuclear cells from patients with Down syndrome.

Down syndrome is associated with immune deficiencies which result in increased incidences of respiratory infections and lymphocytic leukemia. Peripheral blood mononuclear cells (PBMC) from patients with Down Syndrome were assayed in several in vitro assays following incubation in medium or various concentrations of PR 879-317A (2,3,5,6,7,8-hexahydro-2-phenyl-8,8-dimethoxyimidazo (1,2a) pyridine), a selective immunorestorative agent. PBMC of the patients, incubated in medium, exhibited significantly reduced activities in the natural killer (NK) cell, antibody-dependent cell-mediated cytotoxicity (ADCC), T-cell blastogenesis and leukocyte-inhibition factor (LIF) assays. Incubation in PR 879-317A significantly increased the NK and ADCC activities of PBMC from both patients and healthy subjects. However, the effect was much more pronounced on the patients' cells increasing their NK and ADCC activities to normal levels. Incubation in PR 879-317A augmented to normal levels the responses of patients' cells in various assessments of T-cell immunity including blastogenic responses to phytohemagglutinin and concanavalin A and production of LIF. In addition, the number of patients' cells forming spontaneous rosettes with sheep red blood cells was increased following incubation in PR 879-317A. In contrast this compound did not significantly modify the T-cell responses of cells from the healthy subjects suggesting that this compound does not affect normal T-cell function.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1987

Inhibition of murine hepatitis virus infections by the immunomodulator 2,3,5,6,7,8-hexahydro-2-phenyl-8,8-dimethoxy-imidazo[1,2a]pyridine (PR-879-317A).

PR-879-317A (2,3,5,6,7,8-hexahydro-2-phenyl-8,8-dimethoxy-imidazo [1,2a]pyridine) has been found to be a T-cell-selective immunomodulating agent. In the current studies, a series of experiments was designed to determine the potential antiviral activity of this compound in mice infected with murine hepatitis virus. In a comparative antiviral experiment, the activity seen was superior to that of levamisole, a known immunorestorative agent. This activity was characterized by an increase in the 21-day survival frequency, a decrease in hepatic discoloration, a decrease in the amount of infectious virus recoverable from the liver, and normalization of serum glutamic oxalacetate and pyruvate transaminase levels. A comparison of treatment routes indicated the relative efficacies as intraperitoneal greater than per os greater than intramuscular greater than or equal to subcutaneous. Alteration of the treatment schedule markedly affected the antiviral effect; prophylactic or therapeutic treatments once or twice daily for 3 days were usually effective. Single treatments begun 4 h before or 24 h after virus inoculation were highly efficacious. Three treatments administered on alternate days, beginning 48 h before virus inoculation, proved moderately effective. Thrice-daily treatments were ineffective, as were treatments with durations of greater than 3 days. The optimal dosage varied according to the treatment route and dosage schedule. When assessed for direct antiviral activity in vitro, PR-879-317A failed to demonstrate any significant activity against murine hepatitis virus. The positive in vivo activity noted might therefore be the result of immune modulation rather than a direct antiviral effect.

Adjuvants, Immunologic↗