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Biomedical subjects

L K Borysiewicz

Publications and source records attributed to L K Borysiewicz.

At least 73 records · Page 4Linked to original sources
PubMed1990

High frequency of memory and effector gag specific cytotoxic T lymphocytes in HIV seropositive individuals.

Human immunodeficiency virus type 1 (HIV-1) specific cytotoxic T lymphocytes (CTL) have been detected in most patients following infection. It has also been suggested that the specific CTL response, which may play an important role in delaying disease in infected humans, may decline during the course of disease progression. We have measured HIV peptide specific CTL precursor frequency by limiting dilution analysis in two healthy seropositive patients whose fresh peripheral blood mononuclear cells (PBM) specifically lysed MHC matched target cells (restricted by HLA B27 and B8 respectively). The frequency of HIV peptide specific CTL precursors is high (3 x 10(-3)-10(-4], but lower than estimates of circulating CTL with the same specific cytotoxic activity present directly in peripheral blood using the same sample (10(-2)-10(-3]. We suggest that this difference may result from terminal effector CTL differentiation in the T cell lineage. This implies that only a subset of CTL effectors have growth potential, whereas relatively higher levels of CTL with lytic activity can be detected in PBM of healthy HIV seropositive patients.

Cytotoxicity, Immunologic↗
PubMed1990

Peripheral blood T cell activation after radioiodine treatment for Graves' disease.

Radioiodine therapy for Graves' thyrotoxicosis produces a rise in thyroid autoantibodies in the first three months after treatment, but little is known of its effects on T cells. We have therefore followed the changes in T cell subsets in sequential samples from 23 patients with Graves' disease treated with radioiodine, using dual-colour flow cytometry. In the first month after treatment there was a significant rise in activated T cells, identified by the markers HLA-DR (la) and CDw26/Ta1 (p less than 0.025 in both cases). CD45RO-positive T cells, which are the primed population containing memory cells, also increased (p less than 0.025), but there was no change in CD45R-positive, resting T cells or in the CD4 to CD8 (helper to cytotoxic/suppressor) ratio. Vicia villosa-binding T cells, containing the contrasuppressor population, showed a more variable response, but the trend was to an overall increase from pre-treatment values (p less than 0.025). The changes did not appear to be related to antithyroid drug treatment, since they were seen irrespective of whether patients continued such therapy. These results suggest that T cell activation and enhanced contrasuppressor activity may in part be responsible for the rise in autoantibodies after radioiodine. The T cell changes could also contribute to the worsening of ophthalmopathy seen in some radioiodine-treated patients.

Adult↗
PubMed1989

Expression of an intercellular adhesion molecule, ICAM-1, by human thyroid cells.

Intercellular adhesion molecule-1 (ICAM-1), hitherto identified on activated B cells, macrophages, dendritic cells, endothelia and certain epithelial cells, serves as a ligand for the lymphocyte function-associated antigen-1 (LFA-1). ICAM-1 binding by LFA-1 enhances the efficiency of lymphocyte-target cell and lymphocyte-accessory cell interactions. We have investigated the in-vitro expression of ICAM-1 by cultured thyroid cells from five patients with Graves' disease using indirect immunofluorescence analysis, and found that 30 +/- 11% (mean +/- S.D.) of cells were ICAM-1 positive under basal conditions. The proportion of cells which were ICAM-1 positive and the amount of ICAM-1 per cell (assessed by fluorescence intensity) were both increased in all cases by the cytokines gamma-interferon, interleukin-1 and tumour necrosis factor. Immunohistochemical analysis of frozen sections from thyroidectomy specimens demonstrated ICAM-1 on thyroid follicular cells in areas of lymphocytic infiltration in patients with Graves' disease (n = 2) or Hashimoto's thyroiditis (n = 2). ICAM-1 was not found in specimens from a patient with a toxic multinodular goitre or a patient with Graves' disease without focal lymphocytic accumulation. These results suggest that the thyroid epithelium may express ICAM-1 as well as major histocompatibility complex class II antigens, such as HLA-DR, in response to locally synthesized cytokines. The enhanced expression of ICAM-1 may render these cells more susceptible as targets for lymphocyte-mediated cytotoxicity, and together with HLA-DR antigen expression may increase the accessory cell capability of the thyroid follicular cells.

Antigens, Surface↗
PubMed1988

Human cytomegalovirus-specific cytotoxic T cells. Relative frequency of stage-specific CTL recognizing the 72-kD immediate early protein and glycoprotein B expressed by recombinant vaccinia viruses.

CTL are held to be an important host defense mechanism in persistent herpes-virus infections. We have therefore studied the nature and specificity of human cytomegalovirus (HCMV)-specific CTL in normal persistently infected individuals. This was achieved by using vaccinia recombinants encoding viral genes expressed at different stages of the virus replicative cycle, a structural glycoprotein gB (vac.gB) and the major 72-kD immediate early nonstructural protein (vac.IE) of HCMV, combined with limiting dilution analysis of the CTL response. In two subjects, 43 and 58% of HCMV CTL precursors (CTLp) lysed vac.IE-infected cells, in contrast to less than 6% lysing gB-infected cells. HCMV-specific CTL could also be generated by secondary in vitro stimulation with vac.gB- but not vac.IE-infected autologous fibroblasts. The high frequency of 72-kD IE protein-specific CTL suggests that this is at least a major recognition element for the HCMV-specific CTL response in asymptomatic persistently infected individuals, and CTL with this specificity may be important in maintaining the normal virus/host equilibrium.

Antigens, Viral↗
PubMed1988

Human cytomegalovirus-specific cytotoxic T cells: their precursor frequency and stage specificity.

Human virus-specific cytotoxic T (Tc) cells may be important in maintaining the virus/host equilibrium during persistent herpes virus infections such as that with human cytomegalovirus (HCMV). We have previously shown that HCMV-specific Tc cells are present in peripheral blood in normal asymptomatic seropositive individuals (L. K. Borysiewicz et al., Eur. J. Immunol. 1983. 13: 804). In this study we have used limiting dilution analysis to estimate the precursor frequency of these Tc cells and to further delineate their specificity for viral proteins expressed at different stages of the virus replicative cycle. HCMV-specific Tc precursor cells were present in peripheral blood lymphocytes (PBL) at a frequency of 1/5000 to 20,000 E+ PBL. This frequency was higher than that observed for varicella-zoster virus (VZV)-specific Tc cells (1/30,000 to greater than 500,000) in asymptomatic individuals and was similar to the VZV Tc precursor cell frequencies observed following clinical reactivation (1/30,000). When the stage specificity of clonally derived HCMV-specific Tc cells was analyzed, using target cells treated with phosphonoformate to allow expression of only the nonstructural viral proteins, the majority (60%) of Tc cells lysed these cells. A number of Tc cells lysed only cells which expressed the structural or late HCMV proteins. These results suggest a high precursor frequency of HCMV-specific Tc cells in PBL, and that there are subpopulations of such Tc cells specific for HCMV antigens expressed at different stages of the virus replicative cycle. However, the relative frequencies of these subpopulations suggest that the immunodominant HCMV antigens with respect to the Tc response are expressed at immediate early and/or early times.

Cells, Cultured↗
PubMed1988

A study of the structure of the gene for lecithin: cholesterol acyltransferase in four unrelated individuals with familial lecithin: cholesterol acyltransferase deficiency.

1. We have used polyclonal antibodies and a complementary DNA clone for human lecithin:cholesterol acyltransferase (LCAT) to study LCAT protein and the structure of the LCAT gene, respectively, in patients with familial LCAT deficiency from Norway, Ireland, Germany and Italy. 2. The patients had low levels of non-functional LCAT protein in their serum as measured by rocket immunoelectrophoresis; its mol. wt. of approximately 68,000 was identical with that of LCAT in normal plasma, as judged by immunoblotting. 3. Enzymatic digestion of DNA samples from the patients produced LCAT gene fragments which were indistinguishable from those found in normal individuals. 4. We conclude that LCAT deficiency in these patients is not caused by a large deletion or rearrangement of the LCAT gene sequences.

Genes↗
PubMed1988

Suppressive role of NK cells in pokeweed mitogen-induced immunoglobulin synthesis: effect of depletion/enrichment of Leu 11b+ cells.

Natural killer (NK) cells probably have immunoregulatory effects. However, the evidence to date is mainly based on the suppressive effect of enrichment with relatively impure NK populations (large granular lymphocytes, LGL, Leu 7a+ cells). Here we report on the effect of enrichment and depletion of Leu 7a+ and Leu 11b+ cells (the latter containing virtually all NK activity in freshly prepared lymphocytes) on pokeweed mitogen (PWM)-induced immunoglobulin (Ig) synthesis. Enrichment suppressed Ig synthesis to a degree dependent on the number of cells added, and was not enhanced further by their pretreatment with interferon. Furthermore, depletion of Leu 11b+ cells from peripheral blood lymphocytes (PBL) led to marked enhancement (2-25-fold increase) of Ig synthesis, suggesting these cells may normally exert a suppressive effect. The possible underlying mechanisms were investigated further. Enhanced Ig synthesis by Leu 11b-depleted cultures was associated with an increased number of Ig-secreting cells by plaque assay, but with no change in numbers of CD4+ or CD8+ cells. Treatment of PBL with monoclonal antibodies (anti-Leu 7a/Leu 11b) alone suppressed PWM-induced immunoglobulin synthesis. We conclude that NK cells play a role in the regulation of Ig production, at least in part by an effect on activation/differentiation of B cells, but independent of altered T-cell subpopulations. The effect may be unrelated to their cytotoxic function (being unaffected by interferon, IFN), although the direct effects of anti-Leu 11b and Leu 7a in enhancing the suppressive effect suggest an alternative activation pathway.

Antibodies, Monoclonal↗
PubMed1987

Varicella-zoster virus-specific cytotoxic T lymphocytes (Tc): detection and frequency analysis of HLA class I-restricted Tc in human peripheral blood.

The cytotoxic T-cell (Tc) response to varicella-zoster virus (VZV) is incompletely characterized. We investigated whether VZV-specific Tc restricted by class I products of the major histocompatibility complex can be generated from the peripheral blood of VZV-immune donors. Cell lines were established from peripheral blood lymphocytes (PBL) of seropositive donors by secondary in vitro restimulation. If cell-free VZV was used as the stimulating antigen, the resulting lines were predominantly CD4+ and did not show class I-restricted cytotoxicity; when autologous infected fibroblasts were used for in vitro stimulation, the resultant lines were usually cytotoxic, although in only 4 of 11 subjects tested was this cytotoxicity HLA restricted and virus specific. PBL were also tested for Tc activity without prior restimulation; VZV-specific Tc activity was only demonstrable in the PBL of a subject convalescent following zoster but not from subjects with recent varicella infection or from normal subjects. VZV-specific Tc precursor frequencies were then determined in six selected subjects by limiting-dilution analysis. A measurable frequency was detectable in four of the six seropositive subjects, ranging from 11/10(6) T cells in an asymptomatic carrier, to 63/10(6) T cells in a subject with recent zoster. We conclude that virus-specific major histocompatibility complex class I-restricted Tc precursors may be present in the peripheral blood of normal individuals seropositive for VZV but at a frequency lower than that for other herpesviruses with nonneuronal sites of latency.

Cell Line↗
PubMed1987

Regulation of major histocompatibility complex class II antigen expression by the FRTL-5 rat thyroid cell line.

We have used the continuously growing FRTL-5 rat thyroid cell line to examine the regulation of major histocompatibility complex (MHC) class II (or Ia) antigen expression. Of the various stimuli investigated, only the supernatant from activated T cells or recombinant gamma-interferon induced Ia expression. All Ia-inducing activity was removed from the T cell supernatant by acid dialysis, suggesting that gamma-interferon is the single critical mediator for class II antigen expression. Its action was not TSH dependent but expression of class II antigens increased from the G0-G1 to the S and G2 phases of the cell cycle, so that TSH enhanced Ia expression by its action on cell division. Other agents including lectins, hormones, epidermal growth factor, a calcium ionophore and a phorbol ester did not induce Ia expression. Substances known to inhibit murine macrophage Ia expression (cortisol, prostaglandin E2 and 5-hydroxytryptamine) had no effect on FRTL-5 Ia expression. The use of this thyroid cell line has permitted direct examination of modulators in the absence of any possible effects from contaminating non-thyroid cells present in primary cultures and the results suggest that, of the agents tested, only gamma-interferon has significance in the context of Ia antigen expression by the thyroid.

Animals↗
PubMed1986

Human natural killer cell lysis of virus-infected cells. Relationship to expression of the transferrin receptor.

Natural killer (NK) cells lyse tumor and virus-infected cells yet the nature of the target structure they recognize is unknown. A normal host cell glycoprotein, the transferrin receptor (TfR), has been proposed as a target structure on tumor cells. We therefore investigated whether changes in the number or physiological recycling of the TfR, consequent on virus infection, were related to the differential susceptibility of virus-infected cells to NK lysis. There was a direct correlation between TfR expression, susceptibility to NK lysis and ability to act as cold target competitors, for human fibroblasts infected with RNA and DNA viruses (cytomegalovirus, herpes simplex, polio, vaccinia and Semliki Forest virus). The NK lysis of human cytomegalovirus-infected fibroblasts was studied in more detail. NK lysis was increased coincident with human cytomegalovirus early antigen expression and this susceptibility to lysis was associated with increased total and recycling TfR but only a slight increase in surface TfR expression. In addition, susceptibility of uninfected human fibroblasts to NK lysis directly correlated with TfR number. However, we were unable to inhibit NK lysis by either excess iron-saturated Tf or affinity-purified TfR. We conclude that there is a direct correlation between total TfR expression and susceptibility to NK lysis of human virus-infected cells; however, the NK target structure on virus-infected cells is probably not the TfR itself.

Cytomegalovirus↗
PubMed1986

Epstein Barr virus-specific immune defects in patients with persistent symptoms following infectious mononucleosis.

In a number of patients recovery from infectious mononucleosis (IM) following primary Epstein Barr virus (EBV) infection, is complicated by the persistence of symptoms for months or years. Normally recovery from infectious mononucleosis is associated with the development of EBV-specific antibodies and memory cytotoxic T-cells, which are present in the peripheral blood of all normal seropositive individuals. We studied four patients who had persistent symptoms for more than two years after infectious mononucleosis to determine if this abnormality was associated with a defect in EBV-specific or non-specific immune responses. All four patients had normal immunoglobulin concentrations, T- and B-cell numbers, T-cell proliferative responses and natural killer cell activity. However three of the four had reduced or absent antibodies to the EBV nuclear antigen (EBNA) although other EBV-specific antibody titres were normal. All four also had reduced EBV-specific cytotoxic T-cell activity as measured by the EBV regression assay. This defect was probably EBV-specific as alloreactive cytotoxic T-cell responses were normal. In addition, three of three patients tested had reduced in vitro antibody synthesis following pokeweed mitogen stimulation. These studies indicate that the syndrome of persistent symptoms following EBV mononucleosis may be associated with a defect in EBV-specific immunity, and thus suggest a possible immunological basis for the syndrome.

Adolescent↗
PubMed1985

HLA-DR expression in a human colonic carcinoma cell line.

A human colonic carcinoma cell line (HCA-7) isolated from a well differentiated mucoid adenocarcinoma of the colon has been maintained in vitro for 3 years. It spontaneously synthesizes HLA-DR which is mainly intracytoplasmic. Stimulation with lymphocyte conditioned medium and recombinant gamma-interferon results in enhanced synthesis of HLA-DR and the appearance of the antigen on the cell surface. A dose response study showed that maximal stimulation of the culture was achieved with 50 units/ml of recombinant gamma-interferon. Staining for HLA-DR was uneven being confined to focal areas of the monolayer, which is similar to the focal expression of HLA-DR seen in sections of adenocarcinoma of the colon. The functional significance of this phenomenon is unclear, but it may explain the presence of lymphoid infiltrates in tumours.

Adenocarcinoma↗
PubMed1985

Lysis of human cytomegalovirus infected fibroblasts by natural killer cells: demonstration of an interferon-independent component requiring expression of early viral proteins and characterization of effector cells.

We investigated the susceptibility of cells infected with human cytomegalovirus (HCMV) to lysis by human natural killer (NK) cells, examining in particular its relationship to sequential viral protein expression, interferon (IFN), and the nature of the effector cells. HCMV-infected fibroblasts were lysed by peripheral blood mononuclear cells from normal seronegative individuals. The effector cells were large granular lymphocytes of Leu-7+, Leu-11+, and to a lesser extent Leu-7- phenotype. Depletion studies suggested they were the same population of NK cells that lyse uninfected fibroblasts, but a subset of NK cells that lyse K562 cells. HCMV-infected cells treated with phosphonoformate and cells infected for 16 hr that only express the nonstructural HCMV immediate early and early proteins and not the late (structural) proteins were susceptible to lysis by IFN-pretreated effector cells, whereas cells expressing immediate early antigens alone were not. This enhanced susceptibility to lysis was associated with increased effector:target binding in target cell binding assays, and was competitively inhibited by uninfected fibroblasts in cold target competition assays. It was independent of IFN release from the infected target cells or effector cells. These results suggest that the increased susceptibility to lysis by NK cells produced by a human herpes virus HCMV i) is manifest when early viral proteins are expressed, ii) is related to enhanced expression of a target structure likely to be present on uninfected fibroblasts, and iii) has a major component that is independent of IFN.

Adult↗
PubMed1985

The immunosuppressive effects of measles virus on T cell function--failure to affect IL-2 release or cytotoxic T cell activity in vitro.

Measles virus (MV) is known to depress T cell function. In order to determine whether this results from alteration in the production of, or response to, interleukin-2 (IL-2) we studied the effect of in vitro infection with MV on human IL-2 dependent T cell lines. MV produced a cytopathic productive infection in these cells. Class I allospecific cytotoxic T cells retained their cytotoxic activity 48 h after infection. Both cytotoxic and Leu 3a/4a positive T cell lines continued to respond to IL-2 by proliferation up to 26 h after infection. The ability of human tonsillar lymphocytes to generate IL-2 in response to phytohaemagglutinin following MV infection was then studied. In early measles infection (up to 48 h) there was no suppression of IL-2 production: in fact measles infected cells spontaneously released low levels of IL-2 in the absence of lectin. Similarly, IL-2 release was not affected by Herpes simplex virus infection of such cultures, although lymphocytes infected with Sendai or respiratory syncytial viruses produced considerably less IL-2. These observations suggest that MV-induced immunosuppression is not a result of inhibition of differentiated T cell function, IL-2 generation or responsiveness, but may be more directly related to virus-induced cytopathic effects in activated T cells.

Cell Line↗