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Biomedical subjects

A Balsari

Publications and source records attributed to A Balsari.

At least 37 records · Page 2Linked to original sources
PubMed1999

High level antibody response to retrovirus-associated but not to melanocyte lineage-specific antigens in mice protected against B16 melanoma.

Mice vaccinated with Mycobacterium tuberculosis Ag38 gene-transduced B16 melanoma cells showed significant protection from intravenous challenge with parental B16 melanoma cells. No cytotoxic T-cell activity was found against melanoma cells, although the endogenous presence of the mycobacterial gene induced a preferential Th1 response. After immunization, a low serological response against melanoma cells was detected, while a high titer of antibodies directed to parental B16 cells, mainly of IgG2(a) isotype, was found in protected mice after challenge. These antibodies exhibited complement-dependent cytotoxicity against melanoma cells in vitro, while in vivo, used in passive immunization, they induced a decrease in a number of experimental B16 lung metastases. Most of the antibodies were directed against endogenous murine leukemia viruses. No reactivity against melanocyte lineage-specific antigens was observed. In particular, no reactivity was found in sera from protected mice against tyrosinase-related protein 2 (TRP-2), either stably expressed in a non-melanoma cell line or obtained by in vitro transcription-translation, or against tyrosinase, TRP-1 and gp100 antigens immunoprecipitated from B16 cells. Thus, in the B16 murine model, the presence of dominant viral antigens induces a very strong humoral response that might be protective and may inhibit or mask the presence of minor clonotypes.

3T3 Cells↗
PubMed1999

Generation of CD28- cells from long-term-stimulated CD8+CD28+ T cells: a possible mechanism accounting for the increased number of CD8+CD28- T cells in HIV-1-infected patients.

According to CD28 molecule expression, CD8+ T cells can be classed as CD28bright, CD28dim, and CD28-. The CD28dim T cells were found to derive from mitogenic stimulated CD28-T cells but also from CD28bright T cells through a mechanism of CD28 down-modulation. Moreover, after prolonged in vitro interleukin-2 stimulation, clonal CD28bright, cells showed a CD28dim expression before further evolution to a stable CD28-phenotype. This loss was concomitant with the disappearance of CD28 mRNA. A study of the cytokine production pattern revealed that CD28dim and CD28- T cell clones produced similar levels of type 1 and type 2 cytokines, which differed from those produced by the CD28bright T cell clones. A high percentage of CD28dim and CD28- cells, with similarities in their cytokine production pattern, were found in the blood samples of HIV-infected patients, as compared to healthy donors. The CD28 down-modulation may account for the increased number of CD8+CD28- T cells in HIV-infected patients.

Adult↗
PubMed1999

Inhibition of fibronectin-activated migration of microvascular endothelial cells by interleukin-1alpha, tumour necrosis factor alpha and interferon gamma.

The effect of interferon gamma (IFN) and the inflammatory cytokines tumour necrosis factor alpha (TNF) and interleukin 1alpha (IL-1) on micro- and macrovascular endothelial cell (EC) proliferation and migration was analysed. Whereas both micro- and macrovascular EC were growth-inhibited in response to the aforementioned cytokines, only microvascular EC were sensitive to TNF, IL-1 and IFN as inhibitors of fibronectin-activated cell migration. In addition, because microvascular EC play a crucial role in angiogenesis, and the formation of new capillaries depends upon the presence of angiogenic polypeptides, we evaluated the synthesis of fibroblast growth factor (FGF) type 1 and 2, Vascular Endothelial Growth Factor (VEGF) and Hepatocyte Growth Factor (HGF) in our system. Both micro- and macrovascular EC produce large amounts of FGF-2, which is mainly localized in the nucleus, and almost undetectable levels of FGF-1. In addition, the two cell types synthesize notable levels of VEGF and no HGF. Whether these findings are relevant to the different in vivo functions of EC residing different districts remains the focus of additional studies.

Cell Division↗
PubMed1999

Fluctuation of HER2 expression in breast carcinomas during the menstrual cycle.

The hormonal milieu at time of tumor surgery seems to have a significant impact on survival in premenopausal breast cancer patients. Indeed, surgery performed during the follicular phase of the menstrual cycle was suggested to correlate with a poor prognosis. To investigate the relationship between prognosis and menstrual cycle at time of surgery, we analyzed the expression of some markers associated with tumor aggressiveness, such as the hormone receptors, HER2, p53, Bcl2, and cathepsin D in breast carcinomas obtained from 198 premenopausal women who underwent surgery during different phases of the menstrual cycle. HER2 overexpression was found to fluctuate in hormone receptor-positive tumors. In actual fact, 20% of the tumors removed during the follicular phase scored HER2-positive, versus 8% of those removed during the luteal phase. Similarly, a number of hormone receptor-positive tumor specimens, obtained from the same patients during follicular and luteal phases, were scored HER2-positive when the sample was removed during the follicular phase and HER2-negative when removed in the luteal phase. Southern blot analysis of the HER2 gene indicated that, in hormone receptor-positive cases, the overexpression of HER2 is often not associated with gene amplification. The finding that overexpression of the HER2 gene, associated with tumor aggressiveness, can fluctuate according to the hormonal milieu may explain the increased survival of patients operated during the luteal phase. It is also relevant to the selection and treatment of patients most likely to benefit from anti-HER2 antibody therapy.

Adult↗
PubMed1999

Correlation between tumor vascularity, vascular endothelial growth factor production by tumor cells, serum vascular endothelial growth factor levels, and serum angiogenic activity in patients with breast carcinoma.

Angiogenesis is an important prognostic factor in invasive breast carcinoma. We analyzed sera and tumor samples from 36 patients with primary breast carcinomas to determine the relationship between tumor vascularity, vascular endothelial growth factor (VEGF) production by tumor cells, levels of circulating VEGF (measured by ELISA assay), and levels of endothelial growth factors analyzed by a functional test of human umbilical vein endothelial cells (HUVEC) proliferation. Tumor vascularity was correlated directly with VEGF production by the tumor, indicating that VEGF production is a relevant factor in determining angiogenesis in primary tumor. No correlation was found either between the number of vessels in the tumor or the production of VEGF by tumor cells and the levels of serum angiogenic factors including VEGF. On the contrary, the two serum tests correlated together because a high serum level of VEGF is more frequent in cases with the presence of HUVEC-stimulating growth factors. These data indicate that the principal source of factors stimulating angiogenesis in the primary tumor is the tumor itself. This is an important issue in the context of anti-angiogenic therapeutic approaches, which should be planned to interfere with tumor production of angiogenic factors rather than with circulating angiogenic factors. In conclusion, whereas the vessel count and VEGF production by tumor cells are parameters that give direct information on tumor angiogenesis, long-term follow-up is necessary to determine the clinical significance of the determination of serum HUVEC-stimulating factors in the progression of breast carcinoma.

Breast Neoplasms↗
PubMed1998

Contribution of CD4+, CD8+CD28+, and CD8+CD28- T cells to CD3+ lymphocyte homeostasis during the natural course of HIV-1 infection.

The relationship between the number of circulating CD4+ T cells and the presence of particular CD8+ T cell subsets was analyzed by flow cytometry on PBL from asymptomatic HIV-1-infected patients whose specimens were collected every 2 mo for a total period of 32 mo. Only slight variations were detected in the absolute number of lymphocytes and percentage of CD3+ lymphocytes, whereas both CD4+ and CD8+ T cell subsets showed wide intrapatient variation. Variations in the number of CD8+CD28+ cells paralleled those of the CD4+ T cell subset in each patient tested, while the presence of CD8+CD28- T cells correlated inversely with CD4+ and CD8+CD28+ T cells. These data show that changes in the number of circulating CD4+-and CD8+CD28+ T cells are strongly related to the presence of CD8+CD28- T cells in these patients. Insight into the significance of CD8+CD28- T cell expansion will allow us to understand the mechanisms and significance of the HIV-1- driven change in CD4+CD8+ T cell homeostasis and the basic immunopathology of HIV disease.

CD28 Antigens↗
PubMed1998

Segregation of type 1 cytokine production in human peripheral blood lymphocytes: phenotypic differences between IFN-gamma and IL-2-producing cells in the CD8+ T cell subset.

T cell clones are classified as type 0, 1 or 2 depending on the lymphokines they produce. However, it has remained unclear whether single cells of a given type produce one or several cytokine species. Flow cytometric analysis of peripheral blood lymphocytes (PBL) obtained from 20 healthy donors for the production of the type 1 cytokines IFN-gamma and IL-2 revealed very few cells that co-expressed both cytokines independently of the mitogenic stimulus used for PBL activation. Similarly, kinetic studies of cytokine synthesis indicated a low percentage of IFN-gamma/IL-2 double-positive T cells at all time points. Reverse transcription-PCR analysis of sorted IL-2- and IFN-gamma-positive T cells showed the presence of IL-2- or IFN-gamma-specific mRNA only in those cells expressing the corresponding cytokine. This segregation of the two type 1 cytokines was lost in long-term cultured T cells and in T cell clones. A high percentage of cells expressing only IL-2 or IFN-gamma was observed even when the production of these cytokines was evaluated on CD4- and CD8+ subsets. Moreover, in some healthy individuals, IFN-gamma and IL-2 production by CD8+ T cells was related to CD8+ expression levels and cell size, i. e. IL-2-expressing cells were generally smaller with more intense CD8+ staining as compared with IFN-gamma-producing T cells. These data indicate that activated T lymphocytes are strongly committed in vivo to produce IFN-gamma or IL-2 and emphasizes the independent regulation of the two cytokine genes.

CD8-Positive T-Lymphocytes↗
PubMed1998

Anti-tumor immunity induced by murine melanoma cells transduced with the Mycobacterium tuberculosis gene encoding the 38-kDa antigen.

The Mycobacterium tuberculosis Ag38 gene, which encodes a highly immunogenic protein, was cloned into a retroviral vector in-frame with the leader and the transmembrane portion of the nerve growth factor receptor, and transduced into murine melanoma cell line B16-B78. Significant protection was observed in mice immunized with the transduced melanoma cells and subcutaneously challenged with parental melanoma cells since only 20% of mice developed tumors. Necroscopy of mice immunized with the transduced melanoma cells revealed dramatic inhibition of experimental metastases induced by intravenous (i.v.) inoculation of parental melanoma cells. Moreover, vaccination with transduced cells significantly prolonged survival of mice challenged i.v. with parental melanoma cells. These data indicate that the presence of the mycobacterial 38-kDa protein greatly enhances immunological recognition of structures expressed by the parental melanoma cells. Comparison of Th1 and Th2 responses in mice immunized with parental melanoma cells versus mice receiving the transduced cells revealed a clear predominance of Th1 responses when the Ag38 protein was endogenously expressed. This transduction approach may represent a promising immunotherapeutic strategy for the treatment of cancer patients.

Animals↗
PubMed1998

Lack of polarized type 1 or type 2 cytokine profile in asymptomatic HIV-1-infected patients during a two-year bimonthly follow-up.

The production of type 1 (interferon or IFN-gamma) and type 2 (interleukin or IL-4 and IL-10) cytokines by mitogen-stimulated peripheral blood mononuclear cells (PBMCs) obtained from asymptomatic human immunodeficiency virus-seropositive (HIV+) patients untreated with any antiviral, antibacterial or antimycotic drugs, and from healthy individuals, was evaluated by quantitative ELISA. Patients who were HIV+ were characterized by the absence of abnormal cytokine production. The level of each cytokine differed among individuals in the same group with intersubject variations greater for HIV+ patients than for healthy individuals. The longitudinal evaluation of IFN-gamma, IL-4 and IL-10 production showed intrasubject variations which were particularly marked in HIV+ patients. Accordingly, HIV+ patients and, to a lesser extent, healthy individuals were characterized by a wide spectrum of possible profiles, which were confined to type 0 phenotype. In HIV+ patients no correlation was found between each cytokine level and the number of CD4+ T cells, not even in those with a falling CD4+ T-cell count and clinical symptoms.

CD4 Lymphocyte Count↗
PubMed1998

Evaluation of the balance between angiogenic and antiangiogenic circulating factors in patients with breast and gastrointestinal cancers.

Angiogenesis is a critical determinant of tumor growth. Tumor cells produce or induce angiogenic molecules that act specifically on endothelial cells (ECs) but also release angiostatic molecules. Thus, tumor angiogenesis represents a net balance between positive and negative regulators of neovascularization. Sera from patients with breast or gastrointestinal cancers were evaluated for their capacity to selectively modulate the proliferation of human umbilical vein ECs; sera from 15 of 78 (19%) breast cancer patients and 8 of 53 (15%) gastrointestinal cancer patients induced human umbilical vein EC growth, whereas sera from 4 of 78 (5%) breast cancer patients and 1 of 53 (2%) gastrointestinal cancer patients inhibited EC proliferation. Growth-stimulatory sera were significantly more frequent among postmenopausal (14 of 53) than premenopausal (1 of 25) breast cancer patients; inhibitory activity was observed in 3 of 25 premenopausal patients versus 1 of 53 postmenopausal individuals. The half-life of serum-stimulating and -inhibiting factors seemed to differ, because stimulatory activity but not inhibitory activity was decreased at 5 days after surgery. The levels of vascular endothelial growth factor were elevated in about 45% of patients with growth-stimulatory sera, whereas the serum inhibition of EC growth was found to be due, at least in part, to high levels of soluble thrombospondin.

Breast Neoplasms↗
PubMed1997

T cells from individuals in advanced stages of HIV-1 infection do not proliferate but express activation antigens in response to HIV-1-specific antigens.

Like T cells from healthy subjects, those of HIV-1-infected patients are capable of expressing activation antigens on their surface after antigenic or mitogenic stimulation, but their proliferative activity is strongly reduced or even absent, especially in patients with advanced stages of the disease. The characteristic of expressing activation antigens in response to different stimuli in the absence of cell proliferation is shared by CD4+ and CD8+ T-cell subsets from HIV-1-infected patients. The number of T cells capable of expressing CD25 and CD71 in response to HIV-1-related antigens but not of proliferating increased significantly with the progression of the disease, but the number of T cells capable of expressing the two activation antigens in response to the classic tetanus toxoid recall antigen decreased. The higher numbers of T cells capable of responding to HIV-1-related antigens in conjunction with a reduction in the number of T cells responding to recall antigens may explain the occurrence of different infections, including opportunistic microorganisms, during the more advanced stages of HIV-1 infection. Because the increase in the number of HIV-1 antigen-responding T cells (defined by CD25 and CD71 activation antigen expression) is a characteristic of symptomatic HIV-1-infected patients, expression (by flow cytometry) of these activation antigens on T cells in response to HIV-1 antigens could be used as a new marker of disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Flow cytometric analysis of activation markers on stimulated T cells and their correlation with cell proliferation.

The expression of activation antigens, namely CD25, CD69, CD71, and HLA-DR on T cells from 15 healthy individuals stimulated with different mitogens and specific antigens was evaluated by immunofluorescence assay and flow cytometric analysis and compared with cell proliferation as a function of [3H]thymidine incorporation. CD69 was the earliest expressed antigen on stimulated cells, while HLA-DR was the latest. Regardless of the stimulus used, lymphocytes expressing CD25 and CD71 were always more numerous than cells expressing CD69 and HLA-DR. Variations in the proportion of CD4+ and CD8+ T cells expressing each activation marker were observed with different antigenic stimuli. The expression of each activation marker showed overall agreement with the [3H]thymidine incorporation assay in discriminating between positive and negative immune response. However, no correlation was observed between the percentage of CD25-, CD69-, CD71-, and HLA-DR-positive T cells and the amount of [3H]thymidine incorporation. Moreover, low doses of mitogens and antigens as well as short time of stimulation were sufficient to induce T cells to express activation antigens but not to proliferate. Our data show that results obtained by flow cytometry and [3H]thymidine incorporation may differ qualitatively, at least under certain conditions; this suggests that the 2 assays are complementary, and when combined, may gives a clearer understanding of events leading to efficient cell-mediated immune response.

Amino Acid Sequence↗
PubMed1997

Natural antibodies to IL-2.

Natural antibodies to human interleukin-2 are present in sera of patients infected with human immunodeficiency virus and also, at a lower titre, in sera of healthy individuals. These antibodies could be purified by affinity-chromatography. Purified human anti-hIL-2 antibodies can interfere with lymphocyte proliferation both in the lymphokine activated killer cell assay and in the mixed lymphocyte culture. The neutralizing activity observed in vitro suggests that these antibodies play a role in the elaborate cytokine network by which the immune system regulates its response.

Antibodies↗
PubMed1997

Intratibial injection of an anti-doxorubicin monoclonal antibody prevents drug-induced myelotoxicity in mice.

With few exceptions, the major limit to high-dose chemotherapeutic treatments is the severity and duration of drug-induced myelosuppression. We have recently developed a monoclonal antibody, MAD11, which reacts with the potent anti-tumour antibiotic doxorubicin and other anthracyclines. To protect directly pluripotent stem cells and cells of the haematopoietic microenvironment in the bone marrow against doxorubicin cytotoxicity, the monoclonal antibody MAD11 was injected into the tibial bone of mice before chemotherapeutic treatment. All mice pretreated intratibially with MAD11 and injected with 14 mg kg(-1) body weight of doxorubicin survived, whereas 41% of mice treated with doxorubicin alone died. At a higher dose of doxorubicin (18 mg kg(-1)), early mortality (first 6 days) was similar in the groups, but no deaths were observed thereafter in the intratibially MAD11-treated group, whereas most of the mice treated with doxorubicin alone died. Data obtained in mice injected with P388 leukaemia cells showed that the intratibial injection of MAD11 did not compromise the anti-tumoral activity of doxorubicin. Moreover, the administration of the anti-doxorubicin monoclonal antibody before chemotherapeutic treatment effectively reduced apoptosis induced by doxorubicin in the bone marrow cells. These data suggest the usefulness of monoclonal antibodies against chemotherapeutic drugs in the local protection of bone marrow without influencing the anti-tumour properties of the drug.

Animals↗
PubMed1997

Lymphoid infiltration as a prognostic variable for early-onset breast carcinomas.

Infiltration by lymphoid cells is a common feature of many human tumors, including breast carcinomas, and the degree of infiltration has been suggested to be a measure of the host immune response. Our analyses in a series of 1919 cases of primary ductal and lobular infiltrating breast carcinomas from women with a long-term follow-up revealed: (a) a 16-17% frequency of infiltrated tumors independent of the patient's age at diagnosis; and (b) a strong positive correlation between survival rates and the presence of lymphocytes at the tumor site in patients less than 40 years of age (P = 0.0002) but no association with prognosis in patients 40 years of age or older. Multivariate analysis indicated that lymphoid infiltration is independent of other conventional prognostic factors such as nodal status and tumor size in predicting survival. Thus, a possible immune response against the tumor seems to be relevant only in women with early-onset tumors. Because the immune system is functionally maximum in younger years, declining with age, this finding might reflect a difference in the efficiency of the immune system. Alternatively, the biology of these tumors might differ, leading to a difference in immuno-genicity.

Adult↗
PubMed1996

Oral administration of anti-doxorubicin monoclonal antibody prevents chemotherapy-induced gastrointestinal toxicity in mice.

Gastrointestinal mucositis is a common and painful condition that afflicts a proportion of cancer patients receiving chemotherapeutic drugs including anthracyclines, and it has become the dose-limiting toxicity for a number of chemotherapeutic regimens. The murine monoclonal antibody MAD11 recognizes the anthracycline doxorubicin, and systemic administration of this antibody in mice treated with doxorubicin was found previously to prevent the toxic effects of the drug. The purpose of this study was to determine whether gastrointestinal toxicity associated with doxorubicin can be reduced by oral administration of anti-doxorubicin MAD11 in mice. Our experiments show that orally administered MAD11 antibodies: (a) are essentially not absorbed in the blood circulation since less than 0.5% of protein-associated radioactivity was recovered from blood samples; (b) reduce the extent of doxorubicin-induced apoptosis in murine intestinal crypts, as determined by labeling strand breaks with modified nucleotides in an enzymatic reaction; and (c) reduce the body weight loss in mice treated with 12 mg/kg body weight of doxorubicin and decrease the early mortality in mice treated with 16 mg/kg body weight. This type of treatment may be useful in preventing anthracycline-induced gastrointestinal mucositis in cancer patients.

Administration, Oral↗
PubMed1996

Characterization of T cell subsets involved in the production of IFN-gamma in asymptomatic HIV-infected patients.

Cells capable of interferon (IFN)-gamma synthesis following mitogenic stimulation can be detected and quantified by a recently developed immunofluorescence assay and flow cytometric analysis. The production of IFN-gamma was investigated in a cohort of 20 asymptomatic human immunodeficiency virus (HIV)-seropositive patients with normal numbers of CD4+ lymphocytes, and in 10 healthy subjects. About 60% of asymptomatic stage A1 patients had increased percentages of blood lymphocytes capable of IFN-gamma synthesis, as compared to healthy subjects. The difference reflected the relatively higher numbers of CD8+ cells, in particular the CD8+ T cell subset lacking CD28 antigen expression. The strong correlation between the CD4+/CD8+ ratio and the CD8+CD28+/CD8+CD28- ratio suggests either a role for CD4+ cells in controlling the CD28+ phenotype or a role for CD8+CD28- cells in the decline of CD4+ lymphocytes. The peculiar ability of CD8+CD28- cells to produce high amounts of IFN-gamma, as compared to CD8+CD28+ cells, supports the hypothesis that the CD8+CD28- lymphocytes constitute a population that is functionally distinct from their double-positive counterparts.

CD28 Antigens↗