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Biomedical subjects

M G Guerra

Publications and source records attributed to M G Guerra.

10 recordsLinked to original sources
PubMed1995

Variability of the immunoglobulin heavy chain constant region locus: a population study.

The Immunoglobulin Heavy chain Constant region (IGHC) locus is a multigene family composed of highly homologous segments often involved in unequal crossings over that lead to deleted and duplicated haplotypes. The frequencies of these haplotypes in 558 individuals from Lombardy, Veneto, Puglia and Sardinia were determined by Pulsed Field Gel Electrophoresis (PFGE), followed by Southern blotting with four IGHC probes, and compared with those observed in 110 subjects from Piedmont. Twenty deletions and 60 duplications were characterized, all in heterozygous individuals except for 2 homozygous deletions. The differences in frequency between the five populations were not significant. The deletions/duplications involved one or more genes: GP-A2, A1-E and G4 duplications, and A1-E and GP-A2 deletions were the most common. Four new duplications are described: three, involving the genes from GP to A2, from G2 to G4, and G4, are counterparts of known deletions. The fourth duplication spans from GP to G2. A G1 deleted heterozygous individual never previously described in Italy is reported. All the rearranged haplotypes seem to be the result of unequal crossing over. The difference between the number of duplications and deletions was significant in Sardinia, Lombardy, Puglia and in the total of 668 subjects (P < 0.001). This may be due to selection or genetic drift.

Blotting, Southern↗
PubMed1991

Immune material processing by phagocyte cell system in cryoglobulinemia.

An impaired function of splenic macrophages, measured as the clearance rate of erythrocytes coated with IgG (E-IgG), was observed in 7 out of 8 cryoglobulinemic patients with severe urinary abnormalities and systemic symptoms, and in 0 out of 6 patients without urinary symptoms and only mild systemic signs of disease. The E-IgG clearance rate was not related to HLA or Rh phenotype, patients' age or disease duration. Moreover, longitudinal studies showed this parameter to be strictly related to disease activity. To investigate the nature of the defect, five series of analyses were planned using peripheral blood phagocytes (PBP) from 8 patients: a) detection of cell-bound immune material by using the antibody CE59 directed to the Fc fragment of IgG modified by the antibody-antigen reaction; b) cytofluorometric and/or radiometric analyses of the cell surface expression of HLA II, CR1 and FcR structures by means of specific monoclonal antibodies (MoAbs); c) electron microscopy (EM) examination of diverse combinations of cryoglobulins incubated with PBP from patients and normals; d) analysis of cryoglobulin-induced inhibition of E-IgG phagocytosis; e) measurement of the generation of chemiluminescence (CL) in response to Zymosan, Phorbol Myristate Acetate and n-Formyl-Methyonine-Leucine-Phenilalanine (n-FMLP). Patients' PBP were found to have a higher amount of cell-bound immune material as compared to normals (p less than 0.01). CR1 and FcR expression was not different from controls, whereas a slight increase in percentage of monocytes bearing HLA II structures was found in patients (p less than 0.05). Upon EM examination no obvious differences were found in the internalization capacity of cryoglobulins between patients and controls. The CL production was lower than normal (p less than 0.02), whatever stimulus used, with a maximal impairment for n-FLMP (p less than 0.005), the most specific test probe for cytoskeleton integrity. Finally, a remarkable cryoglobulin-induced inhibition of E-IgG phagocytosis was shown. A combination of saturation mechanisms and intracellular abnormalities could underlie the apparent discrepancy between E-IgG clearance defect and preserved potential of cryoglobulin internalization in cryoglobulinemia.

Adult↗
PubMed1990

Altered expression of HLA-A,B specificities on acute lymphoid and myeloid leukaemia blasts.

HLA-A,B specificities were analysed on the neoplastic blasts of a panel of 69 lymphoblastic (ALL) and 50 non lymphoblastic (ANLL) acute leukaemias at onset using the standard lymphocytotoxicity technique. Analysis of the number of detected specificities per locus and, when possible, comparison of the results with those obtained on lymphocytes of the same patients during remission revealed many alterations in the expression of A,B specificities including extra specificities both at the HLA-A and -B loci mainly on lymphoblasts and missed specificities mainly at the HLA-B locus on myeloblasts. Lack of A,B antigens was complete in 6.2% of all tested samples (9% of ANLL) and selective for all the products of one locus in 16.8% of all tested samples (27.7% of ANLL). A decrease of class I molecules on the cell surface was evidenced with MoAb W6/32 on blasts missing detectable serological specificities.

HLA-A Antigens↗
PubMed1990

Wheat protein antigens and effector cells of aspecific immunity.

The effects of gliadin and glyc-gli on leukocyte chemiluminescence response, cytotoxic activity and locomotion were assessed in vitro. A dose-dependent increase in chemiluminescence response of neutrophils stimulated by Zymosan was observed by using gliadin at concentrations ranging between 1 and 20 micrograms. By increasing glyc-gli concentrations, a bimodal response was observed with an enhancement up to 50 micrograms/ml, followed by dose-dependent suppressive effects. The cytotoxic activity of a suspension of peripheral blood mononuclear cells on the human myeloid line K562 was assessed in a Chromium release assay. By pretreating effector cells with optimal doses of gliadin (5 micrograms/ml) or glyc-gli (50 micrograms/ml), an enhancement of cytotoxic activity, similar to that of the gamma-Interferon, could be achieved. Finally glyc-gli was found to elicit neutrophil chemokinesis. The possible implications of these findings in diseases characterized by gluten intolerance are discussed.

Adult↗
PubMed1989

[Sequential study of the immunologic picture in neoplasm patients before and after surgical intervention].

The results obtained in the study of the pre- and postoperative immunological picture in 25 patients suffering from carcinoma of the pavement epithelium of the oesophagus are reported. From this study it emerges that in the preoperative period, the serum levels of immunoglobulin and complement as well as the lymphocyte subpopulations do not present significant changes, whereas 44% of the patients present cell-mediated immunity certified by the skin test. On the other hand, in the postoperative period there is a sharp reduction in the OKT4/8 ratio due in the main to a relative increase in suppressor lymphocytes. In conclusion, the value of skin tests in "in vivo" anergic patient research is underlined, evidencing the need for a programme of immunostimulation in the postoperative period.

Adjuvants, Immunologic↗
PubMed1989

Functional changes of monocytes due to dialysis membranes.

The functional effects directly induced by dialysis membranes on peripheral monocytes were analyzed in a plasma-free model of simulated dialysis using Cuprophan, cuprammonium rayon, polyacrylonitrile, polymethylmetacrilate and polysulphone membranes. A severe reduction of monocyte phagocytosis of IgG-coated erythrocytes was found by using Cuprophan and cuproammonium rayon. The cytofluorimetric analysis of several cell surface receptors, involved in the immune phagocytosis and recognizable by five quoted monoclonal antibodies, did not reveal any significant change. The defective phagocytosis of the IgG-coated erythrocytes by monocytes, due to the exposure to cellulose-derived membranes, was paralleled by an impaired interiorization of heat-aggregated human immunoglobulins, as analyzed by electron microscopy. The cell membrane binding of aggregated immunoglobulins was found to be unaffected. The defect was associated to a remarkably depressed generation of reactive oxygen species after Zymosan stimulation. Therefore, the defective immune phagocytosis induced by exposure of monocytes to cellulosic membranes was not due to a receptor rearrangement or an impaired binding of ingestible particles, but to a reduced internalization capacity probably related to an energy source exhaustion (as shown by the lack of response to stimuli able to induce oxidizing species production). These features are similar to those described in monocytes from acute systemic lupus erythematosus patients.

Cell Survival↗
PubMed1989

Phenotypic and functional analysis of circulating phagocytic cells in IgA nephropathy patients.

We analysed the possible mechanisms responsible for the functional abnormalities reported on phagocyte cell function in IgA nephropathy patients. The oxidative metabolism by the superoxide anion ferricytochrome C reduction test on monocytes and the chemiluminescence response on neutrophils was examined in 32 patients. Moreover the expression of cell membrane structures involved in immune response and phagocytosis (i.e. Fc receptors and HLA class II antigens) was evaluated cytofluorimetrically using specific monoclonal antibodies. Our own results did not show striking differences in oxidative potential and phenotype of patients' phagocyte cells as compared with healthy controls. However a HLA class II-associated structure was found to be quantitatively more expressed in patients' monocytes than in normal controls (P less than 0.005). These findings suggest that the defective phagocyte system function reported in IgA nephropathy patients is not simply due to a loss of cell surface receptors, nor to abnormalities in intracellular metabolic pathways implying oxygen consumption. The increase in expression of some HLA class II structures, often associated with the presence of circulating IgA immune complexes, probably reflects a protracted immunological stimulation.

Adolescent↗
PubMed1987

Immunologic and virologic findings in hemophiliacs do not correlate with ecto-5'nucleotidase activity of peripheral blood lymphocytes. A difference with homosexual men.

It has been recently demonstrated that ecto-5'nucleotidase (5'NT) activity is significantly decreased in the peripheral blood lymphocytes (PBL) of homosexual men. This paper reports a study of PBL 5'NT activity in 38 hemophiliacs at risk for the acquired immunodeficiency syndrome (AIDS). The enzyme activity was correlated to the immunologic and virologic data. T-cell subset distribution was unbalanced and directly correlated with the cumulative amount of AHF infused. PBL 5'NT activity, however, was similar to that of healthy controls. 6 patients displayed serum antibodies to the human immunodeficiency virus (HIV) but no decrease in PBL 5'NT activity. In conclusion, these data indicate that both heavily treated and seropositive as well as untreated hemophiliacs have normal PBL 5'NT activity. This striking dissimilarity between homosexual men and hemophiliacs suggests that some immunologic alterations leading to 5'NT deficiency occur in the former only.

5'-Nucleotidase↗