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S Antonaci

Publications and source records attributed to S Antonaci.

At least 109 records · Page 6Linked to original sources
PubMed1985

Relationship between immune system and gram-negative bacteria: monocyte chemotaxis induced by supernatants from human peripheral blood OKT8+ lymphocytes stimulated with smooth and rough Salmonella strains.

It has been recently reported that smooth (S) Salmonella typhimurium LT-2 and rough (R) mutants, S. minnesota R345 (Rb) and R595 (Re), spontaneously adhere to human peripheral blood mononuclear cells (PBMC). The binding is confined to T cells and is mediated by the lipopolysaccharide (LPS) moiety of the bacteria outer membrane. In this study, we have investigated the monocyte chemotactic responsiveness induced by supernatants recovered from human PBMC stimulated with either S or R Salmonella strains. All supernatants were able to trigger monocyte chemotaxis, even if to a different degree according to the bacterial strain used. These data were further supported by experiments which showed that stimulation of PBMC by purified homologous LPS led to the release of a chemotactic lymphokine (CLK) for human monocytes. Moreover, this CLK seems to be released by T cells, and in particular OKT8+ cells, since OKT8- PBMC failed to produce CLK.

Antibodies, Monoclonal↗
PubMed1985

Impairment of T immunoregulatory activities in the induction of antibody specific response in aged humans.

T helper (Th) and T suppressor (Ts) functions on the induction of specific antibody response have been studied in 80 aged individuals by means of a plaque-forming cell assay. Of the subjects 45.2% exhibited a reduction of Ts activity on Ig production by adding Concanavalin A (Con A) to cultures on day 0, while 35.7% of aged donors showed a decrease of Th functions by supplementation of Con A on day 2. A small number of individuals displayed a combined deficit (Th + Ts). Furthermore, these defects seem to be related to soluble suppressive factors which might adhere to cell surface. In fact, preincubation of peripheral blood mononuclear cells (PBMC) before their addition to cultures and resuspension in fresh medium normalized the immunoregulatory defects. On the other hand, overnight supernatants from old PBMC transferred to young PBMC cultures induced the same deficit observed in the aged cell suspensions. Finally, Zinc chloride supplementation to cultures was able to correct the deficient Th activity only. These data suggest an additional defect of immunoregulation in the elderly.

Adolescent↗
PubMed1985

Relationship between immune system and gram-negative bacteria. III. Functional analysis of human peripheral blood lymphocyte subpopulations separated by cytoadherence with Salmonella minnesota Rb.

Spontaneous adherence of bacteria to human peripheral blood mononuclear cells (PBMC) represents a useful tool for analysis of lymphocyte subsets with different functions. We have recently shown that PBMC can be divided into 2 populations based on their ability to bind Salmonella minnesota R345 (Rb) bacteria. By using these procedures, here, we provide evidence that Rb-bound and Rb-unbound PBMC populations give similar proliferative responses to phytohemagglutinin (PHA) and concanavalin A (Con A), while the pokeweed mitogen (PWM)-induced proliferative and differentiative responses are higher in the Rb-unbound than in the Rb-bound PBMC fraction. Moreover, enhanced PWM-induced responses are obtained in Rb-unbound cell cultures enriched for T4+ cells. When B (non-E rosetting) cells are cultured with purified T lymphocytes from the Rb-bound (T-Rb+) and Rb-unbound (T-Rb-) fractions, comparable PWM-induced mitogenic responses are observed. The T-Rb- population contains a higher percentage of cells expressing T4+ phenotype, and when added to B cell cultures a more elevated PWM-induced IgA, IgG and IgM synthesis is observed than in B cell cultures containing T-Rb+ cells. These results suggest that the T-Rb- fraction is enriched for T cells which help IgA, IgG and IgM responses.

B-Lymphocytes↗
PubMed1985

Relationship between immune system and gram-negative bacteria. IV. T lymphocytes from Lpsd mice possess binding site(s) for Rb Salmonella.

We have previously shown that Salmonella minnesota R345 (Rb) spontaneously binds to 50 to 55% of human peripheral blood mononuclear cells (PBMC). In the present study, we have compared Rb cytoadherence to lymphoid cells from various tissues of lipopolysaccharide (LPS) hyporesponsive (Lpsd) and LPS responsive (Lpsn) mouse strains. A higher number of spleen cells from Lpsd mice (C3H/HeJ and C57BL/10ScN) bound Rb bacteria (22 to 30%) than cells from Lpsn mice (4 to 9%). Rb bound mainly to T cells, and cytoadherence occurred in both Lyt-1+ and Lyt-2+ T cell subsets. By contrast, purified splenic B cells from Lpsd and Lpsn mice gave less than 4% Rb cytoadherence. In both mouse strains, cytoadherence was mediated by the homologous LPS structure, because purified Rb-LPS blocked Rb Salmonella binding to T cells. On the other hand, smooth Salmonella typhimurium LT-2 LPS (S-LPS) and Salmonella R595 (Re) LPS (Re-LPS), which contain mainly lipid A, were without effect on Rb binding. Increased Rb binding was seen with T cells from Peyer's patches (PP), mesenteric lymph nodes (MLN), and peripheral blood than from spleen of C3H/HeN (Lpsn) mice; however, greater cytoadherence was always seen with T cells of these tissues from C3H/HeJ mice. Interestingly, treatment of whole spleen or purified T cells from C3H/HeN mice with neuraminidase enhanced cytoadherence to levels seen with C3H/HeJ cells. The observed Rb binding to PP, MLN, and PBMC cells in both mouse strains suggests that gut microbial environment may play an important role in Rb cytoadherence. This is also supported by the evidence that when spleen cells of germfree and conventional mice were tested for Rb binding, higher cytoadherence was observed in conventional mice only. Taken together, these results indicate that T cells of Lpsd mice express binding site(s) for Salmonella, whereas Lpsn mice have T cells with these structure(s) in a cryptic configuration.

Adhesiveness↗
PubMed1985

Monocyte chemotactic responsiveness triggered by Lymphocyte-Derived Chemotactic Factor in aged donors. Definitive report.

Monocyte chemotactic responsiveness triggered by autologous Lymphocyte-Derived Chemotactic Factor (LDCF) has been evaluated in a group of aged donors. LDCF obtained from Peripheral Blood Lymphocytes (PBL) supplemented with varying numbers of monocytes from aged donors gave a lower chemotactic response when compared to young donors. Moreover, when cell suspensions were pretreated with indomethacin (INDO) before LDCF production, an enhancement of LDCF-induced chemotaxis was observed in old individuals, this implying a prostaglandin-mediated suppression on LDCF release in the elderly. This lymphokine seems to be produced by T cells and, above all, OKT8+ cells, whose frequency is lower in aging. Interestingly, LDCF obtained from OKT8+ enriched cells supplemented with autologous monocytes induced in aged donors a chemotactic activity comparable to that observed in young subjects. These data suggest that the lower frequency of OKT8+ cells in the aging may play a key role in the impairment of LDCF-mediated monocyte chemotaxis.

Adolescent↗
PubMed1984

Non-specific immunity in aging: deficiency of monocyte and polymorphonuclear cell-mediated functions.

Peripheral blood monocytes obtained from 55 aged donors were evaluated for their chemotactic and phagocytic capacity. In the same subjects, polymorphonuclear cell-mediated functions were studied by chemotaxis, phagocytosis, nylon fiber adherence and nitroblue-tetrazolium reduction assay. Monocytes showed a normal chemotactic responsiveness to zymosan-activated serum, while the chemotactic activity induced by leukocyte-derived chemotactic factor and phagocytosis were rather depressed. A dramatic impairment of polymorphonuclear cell-mediated immune response was also observed. In fact, in spite of a normal nylon fiber adherence, chemotaxis, phagocytosis and nitroblue-tetrazolium reduction capacity were significantly depressed by the aging process. These data suggest that the deficiency of non-specific immunity may play an important role in the increased susceptibility to infections in aged donors.

Adult↗
PubMed1984

Relationship between immune system and gram-negative bacteria. II. Natural killer cytotoxicity of Salmonella minnesota Rb 345-unbound human peripheral blood lymphocytes.

Spontaneous binding of human peripheral blood lymphocytes (PBL) to bacteria represents a promising approach for the characterization of lymphocyte subsets mediating different functions. In the light of previous findings on the high degree of spontaneous adherence of S. minnesota Rb cells to PBL, we have evaluated the natural killer (NK) cytotoxicity of PBL subpopulations that fail to bind to Rb bacteria. The S. minnesota Rb-unbound cell fraction exhibits higher levels of cytotoxic capacity, which is related to a more elevated frequency of active NK cells, as determined in an agarose-single cell cytotoxic assay. Moreover, the cytotoxic activity of the unbound fraction is additionally boosted by interferon-alpha pretreatment. The effector cells bear Fc gamma receptors that are involved in NK cell lysis, because a decrease of NK activity is observed after immune complex modulation of the receptors. Finally, these cells, which display a high percentage (approximately 70%) of typical large granular lymphocyte morphology, express HNK-1, T10, T8, and M1 antigens, and to a lesser extent T3 and T4 antigens. These data indicate a selective enrichment of NK cells in the S. minnesota Rb-unbound fraction.

Adhesiveness↗
PubMed1984

In vitro effects of human lipoproteins on the immune system in healthy donors: inhibition of plaque forming cell generation and decreased frequency of NK cells.

The effects of human high density lipoproteins, low density lipoproteins and very low density lipoproteins on spontaneous plaque forming cell (PFC) generation have been evaluated in healthy donors. Additionally, natural killer (NK) cytotoxicity using either 51Cr release assay or agarose single cell system has been studied under identical experimental conditions. A significant inhibition of spontaneous PFC capacity was observed. Furthermore, lipoprotein (LP) pre-treatment led to a reduced frequency of cells mediating NK cytotoxic activity as shown by the decreased binding capacity, even if the killing function was per se not affected. Taken together, these results suggest an inhibitory role for human LP on certain immune functions, likely related to the imbalance of lymphocyte metabolic pathway.

Adult↗
PubMed1984

Relationship between immune system and gram negative bacteria. I. Spontaneous binding of smooth and rough Salmonella to human peripheral blood lymphocytes.

Over the past years many reports have emphasized that either Gram positive or Gram negative bacteria possess the ability to bind spontaneously to human peripheral blood lymphocytes (PBL). Here, bacterial binding to human PBL has been studied by using a smooth (S) Salmonella typhimurium LT-2 and two rough (R) mutants of Salmonella minnesota R 345 (Rb) and R 595 (Re), which possess specific deletions in their lipopolysaccharide (LPS) molecule. Our results provide evidence that all three bacterial strains spontaneously bind to PBL, even though Re and mostly Rb cells display the highest degree of adherence. The three major regions of LPS (O-polysaccharide chain, R core and lipid A) seem to be involved in the binding since adherence is specifically inhibited by pretreating PBL with S- or R-LPS extracted from homologous bacteria. Furthermore, using a panel of monoclonal antibodies to lymphocyte surface antigens, S- and R-Salmonella bacteria bind to T lymphocytes (preferentially T8+ cells), while few B cells are coated by bacteria. Additionally, bacterial binding is significantly reduced by trypsin pretreatment of PBL, this suggesting that proteins (or glycoproteins) of the PBL membrane are involved in the binding.

Antigens, Surface↗
PubMed1983

Abnormal T-cell functions in B-cell chronic lymphocytic leukemia do not imply T-lymphocyte involvement in the leukemic process: report of a case with demonstrated "polyclonality" of T lymphocytes.

In a patient with chronic lymphocytic leukemia (CLL), we previously demonstrated by glucose-6-phosphate isoenzyme analysis that monoclonality was restricted to B lymphocytes. Isolated T cells expressed both isoenzymes and, therefore, were apparently not involved in the leukemic process. This report presents results of a functional analysis of the patient's T cells. Cutaneous anergy to a battery of skin tests was correlated with abnormal proliferative responses of isolated T cells to phytohemagglutinin and concanavalin A. The addition of sufficient numbers of autologous adherent cells restored mitogen responses to nearly normal levels. However, the patient's T cells failed to provide help for differentiation of allogeneic B cells in response to pokeweed mitogen. These data suggest that altered cellular immunity in CLL is not necessarily due to intrinsic T cell abnormalities. Reduced numbers of circulating accessory cells and/or an imbalance in T-cell subsets related to the expansion of the leukemic B-cell clone may play a significant role.

B-Lymphocytes↗
PubMed1983

Phenotypic immaturity of T and B lymphocytes in cord blood of full-term normal neonates. Analysis of cell surface markers by using conventional techniques and monoclonal antibodies.

We examined mononuclear cell subsets in cord blood of normal newborns by surface marker analysis. The percentages of T lymphocytes (E-rosetting and T3+ cells) were lower in cord blood than in peripheral blood (PB) from adults, while the percentage and absolute number of T6+ cells were higher in cord blood. As the sum of T4+ and T8+ cells exceeded the values of E-rosetting lymphocytes in cord blood, we suggest that immature lymphocytes with the phenotype of 'common' thymocytes (T6+, T4+, T8+) are present in cord blood of full-term newborns. Higher percentage and absolute number of B lymphocytes were detected in cord blood. More than 50% of B cells in cord blood formed rosettes with mouse erythrocytes, a surface marker of functional immaturity. Finally, cells bearing receptors for IgG-Fc fragments or C3 and expressing Ia-like and M1 antigens were uniformly increased in cord blood, suggesting higher percentages of cells of the monocytic lineage.

Adult↗
PubMed1983

Analysis of mononuclear cell subsets in pregnancies with intrauterine growth retardation. Evidence of chronic B-lymphocyte activation.

We have examined the mononuclear cell (MC) subpopulations of 5 pregnant women: Three of them had a previous history of IUGR, whereas two were primiparae and presented IUGR at the term of gestation. IUGR was confirmed after delivery in three women. The analysis of MC subsets was performed by rosetting and immunofluorescence techniques; both heterologous antisera specific for human immunoglobulins and monoclonal antibodies specific for T cell antigens and for M1 and Ia-like antigens were used. The three patients with IUGR confirmed at birth presented numbers of circulating lymphoid cells positive for cytoplasmic IgM, IgG and IgA and with morphologic features of plasmablasts or plasma cells at least tenfold higher than in normal pregnant women at the term of gestation. Our data suggest that chronic activation of the lymphoid system occurs in pregnant women with IUGR. Maternal abnormal reactivity to fetal antigens or to undiagnosed chronic infections may be likely explanations for this phenomenon. Further studies are clearly needed to clarify the relationship between B-lymphocyte activation and pregnancy and to examine the hypothesis of an altered balance of the immunoregulatory T lymphocyte subsets in patients with IUGR.

B-Lymphocytes↗
PubMed1983

Humoral immune response in aged humans: suppressor effect of monocytes on spontaneous plaque forming cell generation.

In 50 old donors antibody synthesis has been detected using a protein A haemolytic plaque assay. Data provide evidence that the plaque forming cell (PFC) capacity of aged peripheral mononuclear cells (PBMC) is significantly depressed (0 . 01 greater than P greater than 0 . 001) in comparison to controls. Additionally, suppression is mediated by adherent cells, since monocyte depleted lymphocytes regain the ability of generating spontaneous plaques. The inhibitory effect of monocytes seems to be prostaglandin-dependent, since indomethacin pre-treated PBMC give rise to a normal number of plaques when compared to young mononuclear cells.

Adult↗