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Biomedical subjects

G Melioli

Publications and source records attributed to G Melioli.

At least 73 records · Page 4Linked to original sources
PubMed1988

An in vitro model for Toxoplasma infection in man. Interaction between CD4+ monoclonal T cells and macrophages results in killing of trophozoites.

The cell interactions that take place between Toxoplasma gondii trophozoites and the human immune system have been investigated by using an in vitro model of infection. PBMC were co-cultured with live, appropriately attenuated, trophozoites. When cells from immune (seropositive) donors were used, a proliferative response was observed. At the same time, the proliferating T cells proved capable of controlling the growth of live trophozoites. By contrast, cells from seronegative donors failed to mount a proliferative response and intracellular overgrowth of trophozoites with subsequent cell injury occurred. Actively proliferating T cells were expanded in continuous cell lines with IL-2 and periodical restimulation with Ag in the presence of autologous irradiated mononuclear cells. From some of the lines obtained, clones were also derived. Ten clones were selected for further studies. They proliferated in response to trophozoites but not to unrelated Ag. Their response required the presence of autologous monocytes-macrophages isolated from peripheral blood on Percoll density gradients. B cells that were obtained from the same donors and immortalized by EBV infection proved inefficient as APC. These data suggest that live trophozoites have to be processed by macrophages in order to be presented to T cells. Upon appropriate antigen stimulation, all of the clones produced IL-2 and IFN-gamma, a finding that was consistent with both their CD4+ surface phenotype and their helper capacity on B cell proliferation and differentiation in vitro. The supernatants of all of the stimulated clones released a factor that activated macrophages to kill intracellular trophozoites as well as an unrelated pathogen, Listeria monocytogenes. This factor was identified as IFN-gamma because it was neutralized by specific anti-IFN-gamma antibodies. The present in vitro model of response to live protozoa may prove suitable to assess the role of both T lymphocytes and macrophages in intracellular parasite infections in man. Furthermore, this experimental system may be applied to detect specific lesions of cell mediated immunity in a number of immunodeficiency syndromes.

Adult↗
PubMed1988

Clonal analysis of CD4-CD8- human thymocytes expressing a T cell receptor gamma/delta chain. Direct evidence for the de novo expression of CD8 surface antigen and of cytolytic activity against tumor targets.

CD4-CD8- human thymocytes were obtained by treating total thymocyte suspensions with anti-CD4 and anti-CD8 monoclonal antibodies (mAb) and complement. The resulting cell populations contained virtually no CD4+, CD8+ or WT31+ cells and 17-65% CD3+ cells. In addition, analysis of cell reactivity with delta-TCS-1 mAb (specific for the C gamma 2-encoded, nondisulfide-linked form of TcR gamma/delta), revealed the presence of a variable proportion of delta-TCS-1+ cells (the % of delta-TCS-1+ cells were lower than the percentage of CD3+ cells). Upon culture in recombinant interleukin 2 (IL2, in the presence of irradiated mononuclear cells), CD4-CD8- thymocytes underwent extensive proliferation. In addition, a progressive increase of CD8+ cells (but not of CD4+ or WT31+ cells) could be detected. Cells also progressively acquired cytolytic activity against K-562 or fresh melanoma cells. Fresh CD4-CD8- thymocytes were cloned under limiting dilution conditions. The cloning efficiencies were relatively high (1/3 cells); in addition, virtually all the clonal progenies obtained displayed cytolytic activity and expressed the CD3+WT31-delta-TCS-1+ surface phenotype. About half of the clones analyzed were CD8+, whereas none expressed CD4 antigens. We conclude that (a) only delta-TCS-1-reactive, TcR gamma/delta+ cells can be isolated from CD4-CD8- thymocytes cultured in IL2, and (b) the expression of CD8 antigen and of cytolytic activity reflects a true in vitro phenotypic change of CD8-, noncytolytic precursors (and not the preferential growth of few contaminating cells).

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

CD3+4-8-WT31-(T cell receptor gamma+) cells and other unusual phenotypes are frequently detected among spontaneously interleukin 2-responsive T lymphocytes present in the joint fluid in juvenile rheumatoid arthritis. A clonal analysis.

T lymphocytes (E rosetting cells) isolated from the joint fluid of four patients with juvenile rheumatoid arthritis (JRA) were first analyzed for surface antigen expression. Approximately 15% of cells were CD25+ (interleukin, IL, 2 receptor positive), in addition, a remarkable proportion of cells expressed the CD2+3- phenotype. CD3+ cells outnumbered the sum of CD4+ and CD8+ cells as well as the cells reactive with the WT31 monoclonal antibody (which recognizes a framework determinant of the alpha/beta T cell receptor). Purified T cells were cloned under culture conditions (1% phytohemagglutinin, PHA plus IL2) which allow clonal expansion of most peripheral blood T lymphocytes. Under these conditions proliferating cells ranged from 25 to 65%; clones (derived from microcultures containing 0.5 or 0.25 cells/well) were tested for cytolytic activity against P815 cells (in the presence of PHA) or against the natural killer (NK)-sensitive K562 target cells. Fifty-four percent and 73% of clones obtained from the two patients with the polyarticular form of the disease displayed cytolytic activity in the lectin-dependent assay. Cytolytic clones were 22 and 29% in the two patients with single joint involvement. About half of all cytolytic clones displayed NK-like activity. Surface antigen analysis revealed that, in addition to conventional CD3+4+8- and CD3+4-8+, a noticeable fraction of clones (50/202) displayed unusual surface phenotypes. In particular, 33/50 coexpressed CD4 and CD8 antigens; 7/50 were CD2+3-4-8- and displayed NK-like activity; 10/50 expressed CD3 but lacked both CD4 and CD8 antigen and did not react with the WT31 monoclonal antibody. In order to allow selective growth of IL2-responsive cells, T lymphocytes were also cloned directly in IL2. As much as 57% of all clones thus obtained (48/84) displayed cytolytic activity. Moreover, about half expressed unusual surface phenotypes including CD2+3-4-8-, CD3+4+8+ and CD3+4-8-WT31-. Given the accumulation at the site of the joint involvement of unusual T cells, most of which displayed cytolytic activity and were likely to represent cells activated in vivo (IL2 responsive), one may speculate that these cells may be involved in the injury process.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Zoster sine herpete causing encephalomyelitis.

The case of a patient with encephalomyelitis and laboratory signs of a central nervous system herpes zoster infection without cutaneous lesions is reported. The diagnosis was supported by the serological evidence of intrathecal synthesis of specific antibodies against Varicella-zoster virus (VZV).

Acyclovir↗
PubMed1987

Occurrence of lymphocyte proliferative response to thyroglobulin and antithyroglobulin antibodies in normal individuals: lack of correlation with HLA.

Peripheral mononuclear cells (MNC) of patients with autoimmune thyroid disease have been shown to proliferate when cultured with human thyroglobulin (hTg). In addition, such a phenomenon is apparent in a certain number of healthy individuals. In this study we have attempted to correlate hTg-induced MNC proliferation, occurrence of anti-hTg autoantibodies and HLA phenotype (including Class II DR and DQ loci) in a population of HLA-typed normal blood donors. Fourteen out of 56 subjects showed a significant MNC proliferation to hTg. Three of them had anti-hTg autoantibodies in the serum, while none of the hTg-unresponsive subjects showed such antibodies. No correlation with HLA phenotype (including Class II DR5 specificity, referred as associated with Hashimoto's thyroiditis, and DQ alleles) was observed.

Adult↗
PubMed1987

Symptomatic treatment of recurrent malignant pleural effusions with intrapleurally administered Corynebacterium parvum. Clinical response is not associated with evidence of enhancement of local cellular-mediated immunity.

Intrapleural injection of Corynebacterium parvum (CBP) has been recently proposed as a useful symptomatic treatment of recurrent malignant effusions. Although the result is often a fibrotic thickening of the pleura, CBP is thought to stimulate the effector cells present in the effusion and, possibly, to activate the antitumor cytotoxic activity of the pleural fluid mononuclear cells. To test this hypothesis, we studied 7 patients with recurrent malignant pleural effusions caused by lung cancer and evaluated the cellular composition, the proportions of lymphocyte subpopulations, and the cytotoxic activity of mononuclear cells in the pleural fluid before and 7 days after injection of CBP in the pleural space. The CBP treatment induced a marked decrease in the rate of accumulation of pleural fluid (p less than 0.01) and in the concentration of immune effector cells in the pleural exudate (p less than 0.001). These changes were associated with a decrease in the percentages of pleural fluid monocytes and lymphocytes present (p less than 0.01, each comparison) and to a marked increase in the percentages of pleural fluid neutrophils (p less than 0.001). No significant changes in the proportions of T- and B-lymphocytes or in the proportions of helper/inducer and suppressor/cytotoxic T-cells or of natural killer cells were observed in the pleural exudate after CBP treatment (p greater than 0.2, each comparison). In addition, the cytotoxic activity of pleural fluid mononuclear cells was similar before and after CBP treatment (p greater than 0.2), and the levels of interferon, as a marker of immunoactivation of mononuclear cells, were not changed after treatment (p greater than 0.2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1987

HTLV antibodies in Italian patients with multiple sclerosis.

Several observations indicate that a retrovirus might be involved in the pathogenesis of multiple sclerosis (MS). We report that the sera from 40 Italian MS patients did not contain antibodies to the human T-lymphotropic type I (HTLV-I) and type III viruses (HTLV-III) at levels detectable by commercial ELISA kits. Nevertheless, it cannot be ruled out that a distinct retrovirus is the etiologic factor of MS.

Adult↗
PubMed1985

A simple method to detect intrathecal production of specific antimeasles antibodies in cerebrospinal fluid during subacute sclerosing panencephalitis.

The intrathecal production of antimeasles antibodies was studied using the enzyme-linked immunosorbent assay in eight specimens of serum and cerebrospinal fluid (CSF) from patients with clinical signs of subacute sclerosing panencephalitis (SSPE). The test was performed using a 1:5 dilution of CSF and a 1:2000 dilution of serum (ratio 1:400) in order to nullify the physiological gradient of immunoglobulins across the blood brain barrier (BBB). This procedure allowed a rapid and accurate assessment of the synthesis of specific immunoglobulins in the CSF and a good evaluation of the permeability of the BBB. A diagnosis of SSPE was provided in five out of eight patients with clinical signs of the disease. Clinical follow-up confirmed the diagnosis of SSPE in the group of patients with clear evidence of intrathecal synthesis of antimeasles antibodies.

Adolescent↗
PubMed1985

Enzyme immunoassay for evaluation of Toxoplasma gondii growth in tissue culture.

An enzyme-linked immunosorbent assay (ELISA) for the evaluation of growth kinetics of Toxoplasma gondii in tissue cultures was developed. Tissue culture microplates (96 wells) were seeded with Vero cells, infected with a virulent strain of T. gondii, and incubated for different time periods. The ELISA was performed with anti-T. gondii antibodies on the infected cells. The method was simple, rapid, and accurate, and very good correlations between the ELISA results and the percentage of T. gondii rosettes in infected cells, the number of free T. gondii in the supernatant, and the amount of T. gondii antigen in the supernatant were observed.

Animals↗
PubMed1985

In vitro production of different interferon types by cloned human NK cells.

Human peripheral blood null cells were conjugated in vitro with K-562 cells and expanded into continuous cell lines using IL-2 containing medium (CM) and periodical restimulation with phytohaemagglutinin (PHA). Most of these lines were made up of granular blasts expressing high natural killer (NK) activity. When analysed for different surface markers, the large majority of the blasts were E rosette+, T3+, Tac+, DR+, Leu7+ with a variable proportion of cells expressing T8 and M1 antigens (range: 20-80%). In contrast, T4 antigen was expressed by the majority of cells of the control cell lines originated in the absence of K-562 cells. Twenty-nine clones were obtained from one of the above lines using the limiting dilution technique and subsequently maintained in CM for 4 months or more. The majority of these clones maintained their cytotoxic potential and were able to produce different interferon (IFN) types (IFN-alpha, IFN-gamma or both) when growing in CM. In addition in a number of selected clones, simultaneous stimulation with PHA and K-562 cells was able to induce or support the production of both IFN types.

Antigens, Surface↗
PubMed1984

Assignment of human natural killer (NK)-like cells to the T cell lineage. Single allospecific T cell clones lyse specific or NK-sensitive target cells via distinct recognition structures.

The aim of the present study was to define the cell lineage of mixed lymphocyte culture (MLC)-induced natural killer (NK) effector cells. Human MLC cells were plated under limiting microculture conditions in the presence of irradiated spleen cells and interleukin 2-containing supernatant. After 18 days, microcultures were scored for proliferation and for cytolytic activity against specific lymphoblasts and NK-sensitive K562 target cells. About 1 in 7 and 1 in 5 proliferating microcultures had specific or NK-like cytolytic activity, respectively. Moreover, several microcultures exhibited dual (specific and NK-like) cytolytic activity, even when they had been established at relatively low numbers of responding cells/well (0.5-0.25) to ensure a high probability of monoclonality. Direct evidence for the existence of cytolytic effector cells with dual activity was achieved by using clones derived from single MLC T cells by micromanipulation. Out of 26 cytolytic clones so derived, 16 exhibited specific cytolytic activity, whereas 22 lysed K562 target cells. More interestingly, 12 of these 26 clones were active against both types of target cells. Only one of these clones was able to lyse autologous or unrelated target cells. In contrast, all such clones lysed the NK-sensitive cell lines G11, MOLT-4, Raji, Daudi, Chang and T-24. Addition of saturating amounts of B9-4 monoclonal antibody in the lytic assays resulted in the inhibition of the specific cytolysis, but not the NK-like activity of clones with dual cytolytic activity. It thus appears that (a) alloreactive cytotoxic T lymphocytes can mediate both specific and NK-like cytolysis and (b) two independent recognition structures are involved in this dual activity.

Cell Differentiation↗
PubMed1984

Coumermycin inhibition of murine retrovirus replication in cultured cells.

The effect of coumermycin A1 activity on the infection and replication of murine type C retroviruses was studied in vitro. The infectivity of five prototype ecotropic retroviruses was reduced by 50 to 94%, with viral titres decreased up to seven-fold. These values were substantiated by progeny production studies. Similar results were obtained with five strains of xenotropic retroviruses. Delayed inhibition of growth kinetics in mouse SC-1 cells was observed with 7.5 and 10 mg/l of coumermycin A1. This effect was markedly reduced after three cycles of freezing and thawing of the drug. Changes in the absorption spectra of coumermycin A1 were observed after eight cycles of freezing and thawing.

AKR murine leukemia virus↗
PubMed1983

Immunological imbalance in uncomplicated chronic alcoholism.

The lymphocyte response to unspecific mitogenic lectins and the frequency of the lymphocytary populations and two subpopulations (DR- and Fc gamma-positive T-cells) as well as the serum immunoglobulin levels were tested. Blood samples were drawn from 15 volunteers with chronic alcoholism, an no clinical detectable correlated diseases and from 8 healthy subjects as controls. An activation of the immune system was found, characterized by an increase of T lymphocytes, DR-positive T-cells, IgA and IgG. Aspects of this activation are discussed.

Adult↗
PubMed1983

Sensitive micro in situ fluorescent focus assay for detection of murine xenotropic retroviruses.

A sensitive micro in situ fluorescent focus assay (mISFA), which utilizes cell monolayers fixed on a plastic surface, was developed for the detection of NZB xenotropic type C retroviruses grown in mammalian cell lines. The mISFA technique is an easier, more rapid and less expensive assay than other biological tests used to detect these viruses; it gives a more precise viral titer and is slightly more sensitive. This technique allows extension of host-range investigations to include any growing cell cultures and is applicable to various virus-host cell systems.

Animals↗
PubMed1983

Abnormalities of circulating T cell subsets in atopy: influence of specific immunotherapy.

Blood samples of patients with severe respiratory allergic diseases contain increased numbers of T cells bearing surface HLA-DR antigens, indicating the presence of activated T cells. In the same group of patients, MLR3 and MLR4, two monoclonal antibodies (Mab) directed to subsets of activated peripheral T cells, recognize T cell percentages within the normal range. Thus, it seems possible that specialized subsets of activated T cells (HLA-DR+/MLR3-MLR-) are represented in the peripheral blood of atopic patients. Such cells are lacking in patients after specific immunotherapy. Similar results--an increased percentage of 5/9+ T cells in untreated patients and normal counts of 5/9+ T cells in treated ones--were obtained in the two groups of patients by using another Mab, 5/9, which serves as a reliable marker of helper T cells in resting peripheral T lymphocytes. These data further support the concept of a T cell imbalance in allergic patients and suggest a possible role of specific immunotherapy in correcting the modification of peripheral T cell abnormalities.

Adult↗
PubMed1983

T lymphocyte subpopulations in Graves' disease: relationship with clinical conditions.

T lymphocytes were fractionated according to their receptors for IgG (TG) or IgM (TM) and scored in 37 patients with Graves' disease (17 hyperthyroid and untreated. 10 euthyroid on antithyroid drugs, 10 in long-term remission after radioiodine therapy). TG percentages were very low both in untreated and in drug-treated patients. By contrast, normal TG levels were observed in patients in long-term remission. These data are consistent with the hypothesis of a defective suppressor cell activity in Graves' disease.

Aged↗