Search PubMed⌕ Search

Biomedical subjects

L Morelli

Publications and source records attributed to L Morelli.

At least 109 records · Page 6Linked to original sources
PubMed1995

Aggregation-promoting factor in pig intestinal Lactobacillus strains.

Autoaggregation was frequently encountered among intestinal lactobacilli isolated from weaned pigs. The aggregation mechanism was shown to be mediated by the production of a proteinaceous aggregation-promoting factor in two strains of Lactobacillus reuteri. A 32 kDa aggregation-promoting protein was detected in these strains by cross-reaction with rabbit polyclonal antibodies for Aggregation-Promoting Factor produced by the human isolate Lact. plantarum 4B2. Coaggregation reactions of Lact. reuteri strains with pathogenic and non-pathogenic Escherichia coli were detected.

Animals↗
PubMed1995

Expression of bcl-2 protein predicts efficacy of adjuvant treatments in operable node-positive breast cancer.

The proto-oncogene bcl-2 encodes a protein that inhibits apoptosis, a common mechanism of cell death caused by hormone and chemotherapy. We have analyzed bcl-2 protein expression by immuno-cytochemistry in primary node-positive breast cancers in two groups of patients (for a total of 180 cases). One group received adjuvant hormone therapy, the other chemotherapy (cyclophosphamide, methotrexate, and fluorouracil), and both groups were followed for a median time of 63 months. We compared our findings with conventional clinicopathological indicators [menopausal status, number of axillary nodes, histological grade, tumor size and type, estrogen receptor (ER), and progesterone receptor] and with p53 protein expression. bcl-2 protein was present in 65% of the carcinomas (117/180) and it was significantly associated with ER and progesterone receptor and inversely associated with p53 in both the groups of patients treated with adjuvant chemotherapy and tamoxifen. In patients treated either with adjuvant chemotherapy or tamoxifen, relapse-free survival at 5 years was significantly better among patients with bcl-2-positive tumors than in those with bcl-2 negative ones (P = 0.05 and 0.02, respectively). As far as overall survival is concerned, patients with bcl-2-positive tumors had a significantly better outcome in the group treated with adjuvant chemotherapy (P = 0.03). Multivariate analyses were performed for the two treatment groups. In the group treated with tamoxifen, lack of expression of ER and of bcl-2 was the only significant and independent predictor for poor relapse-free survival (P < 0.01). A number of nodes above 3 was the only significant and independent predictor for poor overall survival (P < 0.01). In the cyclophosphamide-methotrexate-fluorouracil-treated group, bcl-2 absence was significant for poor overall survival (P = 0.02) as well as a number of nodes above 3 (P = 0.04) and a tumor size above 2 cm (P = 0.05). For poor relapse-free survival only a number of nodes above 3 (P < 0.01) and progesterone negativity (P = 0.02) were significant and independent predictors of a higher probability of relapse. Thus, in contrast to in vitro data on drug resistance, bcl-2 expression was associated with better outcomes in patients treated with hormone and chemotherapy. Overall, these results suggest that expression of bcl-2 protein and the number of metastatic lymph nodes are independent features predictive of clinical outcome in patients with node-positive breast cancer, irrespective of the type of adjuvant treatment. The determination of bcl-2 protein may prove to be a useful tool to distinguish patients for whom conventional forms of adjuvant therapy are beneficial from those with bcl-2 negative and ER-negative tumors for whom novel therapeutic strategies are needed.

Adult↗
PubMed1994

Human natural killer cell receptors for HLA-class I molecules. Evidence that the Kp43 (CD94) molecule functions as receptor for HLA-B alleles.

GL183 or EB6 (p58) molecules have been shown to function as receptors for different HLA-C alleles and to deliver an inhibitory signal to natural killer (NK) cells, thus preventing lysis of target cells. In this study, we analyzed a subset of NK cells characterized by a p58-negative surface phenotype. We show that p58-negative clones, although specific for class I molecules do not recognize HLA-C alleles. In addition, by the use of appropriate target cells transfected with different HLA-class I alleles we identified HLA-B7 as the protective element recognized by a fraction of p58-negative clones. In an attempt to identify the receptor molecules expressed by HLA-B7-specific clones, monoclonal antibodies (mAbs) were selected after mice immunization with such clones. Two of these mAbs, termed XA-88 and XA-185, and their F(ab')2 fragments, were found to reconstitute lysis of B7+ target cells by B7-specific NK clones. Both mAbs were shown to be directed against the recently clustered Kp43 molecule (CD94). Thus, mAb-mediated masking of Kp43 molecules interferes with recognition of HLA-B7 and results in target cell lysis. Moreover, in a redirected killing assay, the cross-linking of Kp43 molecules mediated by the XA185 mAb strongly inhibited the cytolytic activity of HLA-B7-specific NK clones, thus mimicking the functional effect of B7 molecules. Taken together, these data strongly suggest that Kp43 molecules function as receptors for HLA-B7 and that this receptor/ligand interaction results in inhibition of the NK-mediated cytolytic activity. Indirect immunofluorescence and FACS analysis of a large number of random NK clones showed that Kp43 molecules (a) were brightly expressed on a subset of p58-negative clones, corresponding to those specific for HLA-B7; (b) displayed a medium/low fluorescence in the p58-negative clones that are not B7-specific as well as in most p58+ NK clones; and (c) were brightly expressed as in the p58+ clone ET34 (GL183-/EB6+, Cw4-specific). Functional analysis revealed that Kp43 functioned as an inhibitory receptor only in NK clones displaying bright fluorescence. These studies also indicate that some NK clones (e.g., the ET34) can coexpress two distinct receptors (p58 and Kp43) for different class I alleles (Cw4 and B7). Finally, we show that Kp43 molecules function as receptors only for some HLA-B alleles and that still undefined receptor(s) must exist for other HLA-B alleles including B27.

Alleles↗
PubMed1994

Effect of acute and chronic cobalt administration on carotid body chemoreceptors responses.

Chronic cobalt exposure leads to release and production of erythropoietin and consequently to polycythemia. Accordingly, cellular elements sensitive to oxygen in the carotid body, would manifest responses during acute and chronic cobalt administration. The carotid body, detects gas changes (PO2, PCO2/pH) in the arterial blood and regulates ventilation and circulation by the afferent nerve discharge. We hypothesized that cobalt interacts with an oxygen sensitive mechanism in the carotid chemoreception and in erythropoietin producing cells. Twelve cats were anesthetized, paralysed and artificially ventilated; few fiber preparation of carotid sinus nerve were recorded during close intraarterial injection of cobalt. In another protocol, 12 rats received an intraperitoneal dose of CoCl2 (10 mg/kg) daily for 6 weeks. At the end, the carotid body was fixed in situ by superfusion. Ultrastructural and morphometric studies were made. Acute administration (0.08-2.3 mumol) promptly stimulated the chemoreceptor afferents. Type I cells increased significantly along with erythropoiesis in the chronic cobalt treated rats. The stimulatory effects of cobalt on the carotid body chemoreceptor showed that sensitive mechanisms in the kidney and in the carotid body are similar, and cobalt interacts with the physiological responses of oxygen.

Animals↗
PubMed1994

Potentiometric determination of carbonic anhydrase activity in rabbit carotid bodies: comparison among normoxic, hyperoxic and hypoxic animals.

The catalytic activity of carbonic anhydrase (CA) contained in the glomus cells of mammalian carotid bodies has been determined in vitro by a potentiometric method. Experiments performed on whole rabbit carotid bodies have shown a very low variability, in terms of the overall CA activity, among organs belonging to different animals maintained in normoxic conditions. Repeated assays performed on each carotid body have shown a marked decrease of the overall CA activity after the first assay, thus suggesting the presence of at least two different forms of enzyme. Experiments performed on carotid bodies belonging to rabbits maintained in normal, hyperoxic and hypoxic conditions have shown that the overall CA activity follows the sequence: hypoxic > normoxic > hyperoxic, matching with the corresponding physiological activity of the carotid body.

Animals↗
PubMed1994

Self class I molecules protect normal cells from lysis mediated by autologous natural killer cells.

The surface expression of given HLA class I alleles protects target cells from lysis mediated by natural killer (NK) clones specific for these (or related) alleles. We could define two groups of NK clones specifically recognizing either Cw4 and related C alleles ("group 1") or Cw3 and related C alleles ("group 2"), respectively. Monoclonal antibodies (mAb) to class I molecules should interfere with the interaction between NK receptors and class I molecules, thus resulting in lysis of protected target cells. However, none of the numerous available mAb to class I molecules had this effect. Therefore, we attempted to select new mAb on the basis of their ability to induce lysis of Cw4- or Cw3-protected lymphoblastoid cell lines by "group 1" or "group 2" NK clones, respectively. From mice immunized with phytohemagglutinin (PHA)-activated lymphocytes expressing either Cw3 or Cw4 alleles, two mAb were selected, the 6A4 (IgG1) and the A6-136 (IgM), on the basis of their ability to induce lysis of protected target cell. Both mAb immunoprecipitated molecules which, in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gave two bands of 45 and 12 kDa, typical of the class I heavy chain and beta 2 microglobulin, respectively. It has been proposed (but not proven), that self major histocompatibility complex class I molecules protect normal cells from autologous NK cell lysis. Thus, we used the 6A4 and A6-136 mAb to assess this possibility directly. Cw4-specific ("group 1") and Cw3-specific ("group 2") NK clones were isolated from donors expressing the corresponding (or related) protective C alleles. None of these clones lysed autologous PHA-induced blasts, used as target cells. However, addition of the F(ab')2 of 6A4 mAb or the A6-136 mAb resulted in lysis of autologous target cells by "group 1" or "group 2" NK clones, respectively. These data provide direct evidence that the expression of class I molecules protects normal cells from lysis by autologous NK cells.

Animals↗
PubMed1994

The human natural killer cell receptor for major histocompatibility complex class I molecules. Surface modulation of p58 molecules and their linkage to CD3 zeta chain, Fc epsilon RI gamma chain and the p56lck kinase.

The natural killer cell (NK)-specific p58 surface molecules, recognized by the GL183 and EB6 monoclonal antibodies (mAb), have been shown to represent the putative NK receptor for HLA-C molecules. The interaction between p58 receptors and HLA-C results in inhibition of the NK-mediated target cell lysis. In this study, GL183-EB6+ clones (Cw4-specific), after mAb-induced surface modulation of EB6 molecules, acquired the ability to lyse the Cw4+ C1R cells. In NK clones co-expressing both GL183 and EB6 molecules and unable to kill Cw3-protected target cells, the mAb-induced modulation of EB6 molecules resulted both in selective co-modulation of GL183 molecules and in the lysis of Cw3-transfected P815 murine cells. In line with the co-modulation experiments we also show that the GL183 and EB6 molecules can be co-immunoprecipitated from GL183+/EB6+ clones after cell lysis in the presence of digitonin. The p58 receptor also revealed an association with molecules belonging to the zeta family (i.e. CD3 zeta and Fc epsilon RI gamma chains). Two-dimensional diagonal gel analysis of the p58 complex immunoprecipitated from polyclonally activated p58+ NK cells indicated a preferential association with CD3 zeta chains either in the form of covalently linked zeta-zeta homodimers or in the form of zeta-gamma heterodimers, while gamma-gamma homodimers were detectable in low amounts. However, p58+ clones displaying a unique association with gamma-gamma homodimers could also be isolated. Probing the immunoprecipitated p58 complex with anti-p56lck antibody also revealed an association with this member of the src family. In addition, mAb-mediated signaling of NK clones via p58 molecules induced increments of p58/p56lck association. However, under the same experimental conditions that induced optimal in vivo tyrosine phosphorylation of the CD16-associated CD3 zeta chains, no tyrosine phosphorylation was detected in the p58-associated CD3 zeta chains. In these in vivo experiments neither anti-CD16 nor anti-p58 mAb could induce tyrosine phosphorylation of the gamma chains. Finally, the anti-p58-mediated inhibition of the NK cell triggering via CD16 molecules was not accompanied by a down-regulation of the tyrosine phosphorylation of the CD16-associated CD3 zeta chains.

Antibodies, Monoclonal↗
PubMed1994

Chronic hyperoxic effects on cat carotid body catecholamines and structure.

To account for the loss of O2 chemoreception in the cat carotid body during chronic hyperoxia, we studied the putative neurotransmitter correlates. Also, we studied the structural aspect of the carotid body tissues. We found that catecholamine concentrations increased and that the densecored vesicles in the glomus cells were not depleted, indicating that a lack of transmitters was not the cause for the loss of O2 chemoreception.

Animals↗
PubMed1994

Antibodies to proteins from Pityrosporum ovale in the sera from patients with psoriasis.

In order to analyse the humoral immune response to the commensal yeast Pityrosporum ovale, we developed a western immunoblot technique with a salt soluble extract of P. ovale cytoplasm. In the present study, we tested sera from patients with psoriasis (n = 15), seborrhoeic dermatitis (n = 10), pityriasis versicolor (n = 8), and normal controls (n = 10). Seventy-three per cent (11/15) of the patients with psoriasis showed specific reactivity with a protein derived from P. ovale of estimated molecular mass 120 kDa, and 46% (7/15) of the cases recognized a 100-kDa protein. Sera from pityriasis versicolor and normal donors showed nonspecific reactivity with several bands of lower molecular weight. To characterize the location of the 100 and 120-kDa proteins, we performed a lyticase digestion of the cell wall, and analysed the soluble digested products by western blotting. The sera from psoriasis patients detected several bands in the range 100-120 kDa. The finding of the immunoreactive 120-kDa protein in this fraction suggests its location at the space between cell wall and membrane (periplasmic space). As a control, we performed an extraction of the cytoplasmic proteins of the dimorphic yeast Candida albicans. C. albicans showed a different pattern of banding in SDS-PAGE. Immunoblots with C. albicans did not allow the detection of any related band. A smear was observed in the high molecular weight range consistent with the presence of lipopolysaccharides. The role of the immune response in infection by P. ovale has not yet been fully explored.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Fungal↗
PubMed1994

Spontaneous canine mammary tumors. A model for monoclonal antibody diagnosis and treatment of human breast cancer.

BACKGROUND: The increasing availability of monoclonal antibodies to human breast tumor-associated antigens offers a new means to evaluate whether antigenic similarities exist between human and animal breast tumors. The study of the biology of spontaneous mammary tumors in the dog, one of the most frequent neoplasias in this domestic animal, may be of interest in providing an experimental model for the clinical management of human breast cancer. EXPERIMENTAL DESIGN: In order to assess whether antigenic similarities do occur between human and canine breast cancer, in the present study we have evaluated the immunohistochemical reactivity of two normal mammary glands and 62 benign and malignant canine breast tumors with a panel of six MoAbs, (HMFG2, MBr1, B72.3, B6.2, X-10, B1.1) recognizing distinct human breast tumor-associated antigens. RESULTS: The results of the present study indicate that mammary neoplasias in dogs display an antigenic phenotype comparable to that observed in female and male human breast lesions. As has already been demonstrated in humans, only three among the six monoclonal antibodies tested (B72.3, B6.2, and X-10) appear to discriminate benign from malignant canine mammary tumors. CONCLUSIONS: These findings demonstrate that (a) this veterinary tumor may represent a suitable model for imaging and immunotherapy studies of human breast carcinoma and (b) the triplet of reagents capable of distinguishing selectively transformed glandular epithelium may be useful in the immunocytochemical presurgical diagnosis of these canine neoplasias.

Animals↗
PubMed1994

Negative signalling via the P58/NKR for HLA.C alleles.

Recent studies have demonstrated that the interaction between HLA class I alleles and specific NK receptors results in negative signals which inhibit NK-mediated cytotoxicity. Such NK receptors have been identified by GL183 and EB6 mAbs which recognize distinct members of a molecular family involved in the recognition of two groups of HLA.C alleles. Now we describe a new allospecific NK group (group 0) which recognize all HLA.C alleles and we demonstrate that, on these clones, the p58 molecules EB6 and GL183 act independently to recognize Cw4 (and related alleles) and Cw3 (and related alleles) respectively. Finally we investigate whether the inhibitory signal mediated by the NK-receptor for HLA.C induce a temporary turn off on the cytolytic activity.

Alleles↗
PubMed1993

Triggering of the cytotoxic activity of murine natural killer and lymphokine-activated killer cells through the NK2.1 antigen.

The NK2.1 alloantigen, one of the few NK-specific markers in the mouse, identifies a subset rather than all splenic NK cells. On the basis of the cell surface expression of a variety of Ag of the lymphocytic and monocytic lineages, we establish that BALB/c NK2.1+ cells are heterogeneous and that their phenotype is quite similar to the one reported for NK1.1+ cells. A NK2.1- cell population of the same size and related phenotype was also identified in fresh NK-enriched cell suspensions. After stimulation with IL-2, the only phenotypic trait that distinguishes NK2.1+ and NK2.1- cell subsets is precisely the expression of the NK2.1 Ag. To investigate whether NK2.1+ and NK2.1- lymphokine-activated killer cells would also be identical in their cytotoxic activity, NK-enriched spleen cells were cultured for 5 days with IL-2, sorted afterward on the basis of NK2.1 expression, and compared for their capacity to lyse YAC-1 targets. NK2.1+ cells are significantly more lytic than NK2.1- cells, suggesting that the anti-NK2.1 mAb, used for cell sorting, could have triggered NK2.1+ cells and enhanced their lytic activity. In support to this hypothesis we show that 1) immobilized anti-NK2.1 mAb induces granule exocytosis by LAK cells, 2) soluble anti-NK2.1 mAb specifically inhibits NK and LAK cell-mediated lysis of 4LO3311 hybridoma cells secreting anti-NK2.1 mAb, and 3) binding of anti-NK2.1 mAb selectively enhances the lysis of NK-sensitive targets. Furthermore, the successful activation of NK2.1+ cells induced by anti-NK2.1 F(ab')2 or F(ab) mAb fragments indicates that the triggering mechanism is different from reverse antibody-dependent cellular cytotoxicity and does not require cross-linking of the NK2.1 molecule. Our results strongly suggest that the NK2.1 molecule is implicated in a post-binding NK cell signaling event, and point out the possible functional relevance of this NK-specific Ag in non-MHC-restricted cytotoxicity.

Animals↗
PubMed1993

P58 molecules as putative receptors for major histocompatibility complex (MHC) class I molecules in human natural killer (NK) cells. Anti-p58 antibodies reconstitute lysis of MHC class I-protected cells in NK clones displaying different specificities.

Human CD3-16+56+ natural killer (NK) cells have been shown to display a clonally distributed ability to recognize major histocompatibility complex (MHC) class I alleles. Opposite to T lymphocytes, in NK cells, specific recognition of MHC class I molecules appears to induce inhibition of cytolytic activity and, thus, to protect target cells. Since a precise correlation has been established between the expression of the NK-specific GL183 and EB6 surface molecules (belonging to the novel p58 molecular family) and the specificity of NK clones, we analyzed whether p58 molecules could function as receptors for MHC in human NK cells. NK clones displaying the previously defined "specificity 2" and characterized by the GL183+EB6+ phenotype, specifically recognize the Cw3 allele and thus fail to lyse the Fc gamma R+ P815 target cells transfected with Cw3. On the other hand, NK clones displaying "specificity 1" and expressing the GL183-EB6+ phenotype failed to lyse Cw4+ target cells. Addition of the F(ab')2 fragments of either GL183 or EB6 mAb as well as the XA141 mAb of IgM isotype (specific for the EB6 molecules) completely restored the lysis of Cw3-transfected P815 cells by the Cw3-specific NK clones EX2 and EX4. Similarly, both the entire EB6 mAb, its F(ab')2 fragment and the XA141 mAb reconstituted the lysis of C1R, a Fc gamma R- target cell expressing Cw4 as the only serologically detected class I antigen. Thus, it appears that masking of different members of p58 molecules prevents recognition of "protective" MHC class I alleles and thus the delivering of inhibitory signals. Further support to the concept that p58 molecules represent a NK receptor delivering a negative signal was provided by experiments in which the entire anti-p58 mAbs (of IgG isotype) could inhibit the lysis of unprotected Fc gamma R+ P815 target cells, thus mimicking the inhibitory effect of MHC class I molecules.

Antibodies, Monoclonal↗
PubMed1993

CD45-mediated regulation of LFA1 function in human natural killer cells. Anti-CD45 monoclonal antibodies inhibit the calcium mobilization induced via LFA1 molecules.

The TA218 and T205 monoclonal antibodies (mAb) were selected on the basis of their ability to inhibit the non-major histocompatibility complex-restricted lysis of the murine mastocytoma P815 cell line mediated by CD3-CD16+ natural killer (NK) cells. Both mAb were found to react with CD45 molecules, as demonstrated by immunoprecipitation after surface iodination and western blot analysis. A panel of tumor target cells susceptible to lysis by polyclonal or clonal CD3-CD16+ NK cells was used to study the mAb-mediated inhibitory effect. The inhibition of cytolysis mediated by TA218 and T205 mAb was found to consistently parallel the inhibition mediated (with the same tumor target cells) by the anti-LFA1 alpha mAb TS.1.22 or by the anti-LFA1 beta mAb TS.1.18. However, different from the anti-LFA1 mAb, T205 or TA218 mAb did not inhibit the binding of activated CD3-CD16+ effector NK cells to the same tumor target cells. This finding supported the concept that the anti-CD45 mAb-mediated inhibition could occur at a post-binding stage. In polyclonal or clonal CD3-CD16+ NK cells T205 or TA218 mAb were found to reduce by 50-70% the intracellular Ca++ ([Ca++]i) mobilization induced by anti-LFA1 alpha or anti-LFA1 beta mAb. On the other hand, TA218 and T205 mAb did not inhibit the Ca++ mobilization induced by anti-CD16 mAb or phytohemagglutinin, thus suggesting that, in NK cells, CD45 molecules may exert a selective inhibitory effect on the signal transduction mediated by LFA1 molecules. In line with this hypothesis, the cytolytic activity of human NK clones was triggered in the presence of the hybridoma cells secreting either anti-CD16 or anti-LFA1 alpha mAb (as "triggering targets"). This effect of anti-LFA1 alpha, but not of anti-CD16 hybridoma was susceptible to inhibition by the anti-CD45 mAb T205 or TA218. Further, experiments on cloned NK cells indicated that T205 or TA218 mAb induced a strong decrease in the constitutive phosphorylation of the LFA1 alpha chain (but not of HLA class I antigens). Taken together, these studies suggest that in human NK lymphocytes, CD45 molecule may regulate both the activation state and the function of the LFA1 molecule.

Animals↗