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Biomedical subjects

F Manca

Publications and source records attributed to F Manca.

At least 109 records · Page 6Linked to original sources
PubMed1984

A limited region within hen egg-white lysozyme serves as the focus for a diversity of T cell clones.

The C57BL/6 (H-2b) mouse is a nonresponder to hen egg-white lysozyme (HEL) injected i.p., owing to a T suppressor cell-inducing determinant at the amino-terminal region. After immunization with a 93-amino acid fragment (a.a. 13-105) of HEL lacking this determinant, all clones from two independently derived C57BL/6 T cell lines were found to be specific for epitopes within a subregion of peptide 74-96. Three specificity patterns for the clones could be defined on the basis of cross-reactivities with only two other species variant lysozymes. Reactivities of all three specificity groups was consistent with the serine to threonine substitution at position 91, although reactivity of one of the groups could be affected by substitutions at position 84. The results confirm at the clonal level that even for distantly related antigens, only limited regions are recognized by T cells. They are consistent with the notion that specific sites on the antigen capable of interaction with Ia molecules lead to dominance of certain regions for T cell reactivity. Moreover, the diversity in specificity among clones suggests that the limiting feature of T cell responsiveness is not a lack of available T cells in the repertoire directed against a single antigenic site.

Animals↗
PubMed1984

Follow-up of circulating immune complexes in the course of acute viral hepatitis, and correlation with serologically relevant parameters.

Type A, type B and type non-A, non-B hepatitis patients were followed up. Several parameters were checked at ten day intervals. Circulating immune complexes (CIC) were detected in a large percentage of patients by using the PEG test and an assay that makes use of bovine conglutinin (K) as recognition unit, and an enzymatically labelled immune complex as the probe. The decrease in the mean level of CIC in the patients correlated with the decrease in serum transaminases and bilirubinaemia in type A and type B hepatitis. Although the pattern of the mean values of the two assays was similar for type A and type B hepatitis, when the two CIC assays were compared for each patient, no significant correlation was found. In light of these and previous results, the necessity for performing CIC monitoring with more than one assay is also discussed.

Acute Disease↗
PubMed1983

An enzymatically active antigen-antibody probe to measure circulating immune complexes. II. E. coli beta-galactosidase in the probe and C1q as the recognition unit.

An enzymatically active probe (beta-galactosidase-anti-beta-galactosidase complex) is used to measure circulating immune complexes (CIC), in a competition assay where probe and CIC are confronted with a 'recognition unit'. The latter is bovine conglutinin in the original description of this method. Here we describe a version utilizing human or bovine C1q. The two techniques are compared for their sensitivity and specificity, on both in vitro formed tetanus toxoid-anti-toxoid complexes and on sera from patients with selected diseases. The results confirm that the two recognition units are sensitive to families of CIC that only partially overlap. The parallel use of conglutinin and C1q yields both quantitative and qualitative information on the nature of CIC in individual sera.

Animals↗
PubMed1983

Cold-precipitable immune complexes in collagen diseases: evidence for the coexistence of multiple types of circulating complexes in the same serum.

In patients with systemic lupus erythematosus, mixed cryoglobulinemia, and rheumatoid arthritis, the presence of cold-precipitable immune complexes (IC) was investigated by means of two different methods, i.e., the Clq-binding activity (ClqBA) and a competitive enzyme immunoassay, based on solid-phase bovine conglutinin (K). Cold precipitability of IC ranged between 0 and 100% with K and between 0 and 71% with ClqBA. No correlation existed either between the levels or the cold precipitability of the IC measured by the two systems in the same sera. On the whole, cold-precipitable IC were better determined by the K method than by ClqBA and in mixed cryoglobulinemia cryocrit levels correlated with IC levels determined with K, but not ClqBA. These data provide direct evidence of the coexistence of several types of circulating IC in the same serum and that the two methods recognize, at least in part, different IC in the same specimen. It might be hypothesized that different IC present in a serum may have a distinct biological significance.

Antigen-Antibody Complex↗
PubMed1983

Recognition of donor fibroblast antigens by lymphocytes homing in the human grafted kidney.

A human transplanted kidney, surgically removed because of untreatable chronic rejection, was used as the source of lymphocytes (K-L) of recipient origin that were expanded with interleukin-2 (IL-2), and of kidney fibroblasts (K-F) of donor origin that were maintained as an established line. Cytotoxicity assays were performed using K-L and peripheral blood lymphocytes (PBL) as effectors, and K-F and donor PBL as targets. From the results the following conclusions can be drawn: (1) cytotoxic lymphocytes, presumably involved in the process of chronic graft rejection, home in the kidney (from which they can be recovered) but are not detected in the circulation; (2) cytotoxic lymphocytes can be generated from peripheral lymphocytes by mixed lymphocyte culture (MLC) and further expansion in vitro with IL-2 (MLC-L); and (3) although both K-L and MLC-L are cytotoxic toward K-F, the former are not cytotoxic toward donor PBL. This suggests that although MLC-L recognize antigens shared by K-F and PBL, K-L recognize antigens specific for K-F only. These results, if confirmed, indicate that antigens not present on PBL, and possibly tissue-restricted are important in graft rejection. Thus, while monitoring transplanted patients, a lack of cytotoxicity in the recipient PBL may be misleading because the relevant cytotoxic effector cells may have disappeared from the periphery and the appropriate antigenic target may be absent on donor PBL.

Adolescent↗
PubMed1982

Calorimetric study of the binding reaction of concanavalin A with immunoglublins.

The thermal effects associated with the binding reaction of concanavalin A and immunoglobulins have been measured by calorimetry. IgG solutions do not generate heat on mixing with concanavalin A, confirming the low reactivity of IgG for the lectin molecule. IgM solutions, on the other hand, show a substantial enthalpic contribution of delta H = -24 +/- 1kJ/site for the binding reaction between the polysaccharide chains of human IgM macroglobulin and concanavalin. A stoichiometry is 10 monovalent concanavalin A molecules per intact macroglobulin and two bivalent concanavalin A molecules per two sites on the heavy chain of the reduced macroglobulin subunit.

Calorimetry↗
PubMed1982

Plasma exchange and immune complex diseases: the predictability of immune complexes removal to clinical response.

58 patients were treated by discontinuous flow plasma exchange because of an immune complex (IC) disease. 41 patients who had a high level of circulating IC prior to plasmapheresis showed both clinical and immunochemical evidence of improvement with plasma exchange. Only 2 patients with a high level of IC did not improve after therapy: these patients suffered from multiple sclerosis and idiopathic thrombocytopenic purpura, respectively. Prior to PE therapy the level of circulating IC in 15 patients was within the normal range, when measured according to Manca et al. In this group none of the patients worsened after therapy, whereas 8 patients showed an objective improvement. The positive correlation between IC removal and clinical results suggests that patients with a high level of circulating IC are most likely to benefit from apheretic treatment.

Amyotrophic Lateral Sclerosis↗
PubMed1981

Calorimetric study of manganese binding to concanavalin A.

The reaction of concanavalin A with Mn2+ has been studied calorimetrically. The binding enthalpy was measured at two different temperatures, 25 and 30 degrees C, in 10(-3) M acetate buffer; it was found to be constant between pH 4.0 and 5.0, delta H250 = 95 kJ/mol and delta H300 = 65 kJ/mol, respectively. The two S1 binding sites are identical and independent. Experiments at pH 5.6 are distorted by the heat of aggregation, which is several times higher than the heat of binding. Aggregation was demonstrated by spectrophotometric experiments and by light scattering. The presence of Mn2+ increases the stability of the protein molecule.

Binding Sites↗
PubMed1981

Calorimetric study of concanavalin A binding to saccharides.

The binding of concanavalin A in the dimer form to various saccharides has been studied by calorimetry, and estimates of the binding enthalpy and binding constants have been calculated. Methyl alpha-D-mannoside and methyl alpha-D-glucoside have a -- delta H0 of 21.5 and 11.5 kJ/mol, respectively, at both pH 4 and 4.5. The p-nitrophenyl derivatives react with enthalpic values of 15.6 and 14.6 kJ/mol. The galactosepyranosides show no heat effects during mixing with the protein solutions. The apparent binding enthalpies calculated from the variations of the equilibrium constants with temperature are in good agreement with the values measured experimentally. The two binding sites of the dimer form of concanavalin A are equal and independent, and the low enthalpies obtained do not justify a large conformational change during the reaction. The binding reaction has also been estimated for other sugars normally contained in glycoproteins.

Binding Sites↗
PubMed1981

Patients with high titers of circulating immune complexes are most likely to benefit from plasmapheresis treatment.

Intermittent flow centrifugation system was utilized in the management of 17 patients with IC diseases. 14 out of 14 patients that had high levels of ICs prior to plasmapheresis showed both clinical and immunochemical evidence of improvement with plasmapheresis. 3 patients had no evidence of circulating ICs prior to plasmapheresis: in these cases no apparent result was achieved after the apheretic therapy. Although the striking correlation between IC removal and clinical result is not a formal proof of responsibility of CIC in the pathogenesis of the disease, it is suggested that quantitative determination of CICs (utilizing several different recognition units) may be a useful parameter in the decision to apply plasmapheresis in the therapy of selected autoimmune diseases.

Adolescent↗
PubMed1980

Immune-complexes in malignant skin melanoma: quantitation by three methods, purification, and characterization of their non-tumor related constituents.

Circulating immune-complexes (ICs) and complement system (C) were studied in sera from 10 patients with malignant skin melanoma. The presence of ICs was demonstrated in all of them by three distinct methods. Moreover, ICs were purified in all the patient sera. The fact that ICs were detected in each serum and that the results of the analysis obtained by the different methods were not overlapping is discussed. It is stressed that the differences among the intrinsic characteristic of each technique are responsible for these discrepancies. The C profile was altered if compared with normal values, but it was not strictly characteristic for an ICs disease. In the purified ICs C3, C4, IgM, IgC1, and IgG3 were demonstrated; C1q, C1s, IgA, IgG2, and IgG4 never. It is noteworthy that a rheumatoid activity was found in the purified material and that this activity was significantly correlated with serum immuno-conglutinins (IKs) titre.

Adult↗
PubMed1979

[Intraoperative evaluation of the high pressure zone in anti-reflux plastic operations].

It has been done a manometric intraoperating study on 18 patients (7 acalasical megaoesophagi, 6 herniae of hiatus, 5 duodenal ulcers) who had undergone an operation of modified Dor's anti-reflux plastics. After Haller H.P.Z. pressure has gone down of 13 mmHg, and has gone up again of 5,5 mmHg after modified Dor; after plastics H.P.Z. average intraoperating pressure has been of 18 mmHg. The posterior plastics of hiatus and the reconstruction of His' angle for hernia of hiatus modify scarcely H.P.Z. pressure. During a superselective vagotomy we have recorded a modest reduction of H.P.Z. pressure, of which average intraoperating values after vagotomy and anti-reflux plastics have been of 16,5 mmHg. At a distance of 30 months from the operation it has been done a follow up on 70% of patients that had undergone an operation of anti-reflux plastics and also 18 patients that had had en intraoperating inspection. However it has been, a degradation of manometric values, the results have been satisfactory over 90% of cases. The authors insist on the utility of intraoperating manometry for a valuation of the completenes and the efficacy of the operation.

Adolescent↗