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Biomedical subjects

M A Avanzini

Publications and source records attributed to M A Avanzini.

At least 19 recordsLinked to original sources
PubMed2007

Optimization of in vitro expansion of human multipotent mesenchymal stromal cells for cell-therapy approaches: further insights in the search for a fetal calf serum substitute.

There is great interest in mesenchymal stromal cells (MSCs) for cell-therapy and tissue engineering approaches. MSCs are currently expanded in vitro in the presence of fetal calf serum (FCS); however, FCS raises concerns when used in clinical grade preparations. The aim of this study was to evaluate whether MSCs expanded in medium supplemented with platelet-lysate (PL), already shown to promote MSC growth, are endowed with biological properties appropriate for cell-therapy approaches. We confirm previously published data showing that MSCs expanded in either FCS or PL display comparable morphology, phenotype, and differentiation capacity, while PL-MSCs were superior in terms of clonogenic efficiency and proliferative capacity. We further extended these data by investigating the immune-regulatory effect of MSCs on the alloantigen-specific immune response in mixed lymphocyte culture (MLC). We found that MSCs-PL are comparable to MSCs-FCS in their capacity to: (i) decrease alloantigen-induced cytotoxic activity; (ii) favor differentiation of CD4+ T-cell subsets expressing a Treg phenotype; (iii) increase early secretion of IL-10 in MLC supernatant, as well as induce a striking augmentation of IL-6 production. As compared with MSCs-PL, MSCs-FCS were more efficient in suppressing alloantigen-induced lymphocyte subset proliferation and reducing early IFNgamma-secretion. Resistance to spontaneous transformation into tumor cells of expanded MSCs was demonstrated by molecular karyotyping and maintenance of normal morphology/phenotype after prolonged in vitro culture. Our data support the immunological functional plasticity of MSCs and suggest that MSCs-PL can be used as an alternative to MSCs-FCS, although these latter cells might be more suitable for preventing/treating alloreactivity-related immune complications.

Adolescent↗
PubMed2005

The immunosuppressive effect of human cytomegalovirus infection in recipients of allogeneic hematopoietic stem cell transplantation.

In immune-competent individuals, human cytomegalovirus (HCMV) infection is associated with impairment of T-cell function. Our goal was to evaluate prospectively whether clinically asymptomatic HCMV infection in allogeneic hematopoietic stem cell transplantation (alloHSCT) recipients, treated pre emptively with ganciclovir, influences T-cell function as well. Mitogen-stimulated T-cell proliferative activity, together with cell surface markers, was tested in 49 patients on days + 30, + 45, + 60, and + 90 after alloHSCT and, additionally, in cases of positive HCMV pp65-antigenemia. HCMV infection was diagnosed in 19 patients. None of them developed HCMV disease. T-cell proliferative activity was significantly decreased on days when HCMV antigenemia was positive as compared to days without antigenemia. The number of pp65-positive cells negatively correlated with proliferative response. Comparison of patients who did experience HCMV infection with those who did not reveals significant decrease of T-cell proliferative activity observed on days + 30 and + 45, a time period when antigenemia was most frequently found to be positive, whereas no difference was detected on days + 60 and + 90. We conclude that, even clinically asymptomatic, HCMV infection has negative impact on T-cell proliferation capacity in alloHSCT recipients. However, pre emptive therapy with ganciclovir makes this immunosuppressive effect transient and restricted to the time of infection duration.

Adolescent↗
PubMed2005

IFN-gamma low production capacity in type 1 diabetes mellitus patients at onset of disease.

In type 1 diabetes mellitus (T1DM), cytokines can be directly cytotoxic to beta-cells, and/or play an indirect role influencing some cells of the immune system. Since several factors could impair cytokine serum levels, the purpose of our study was to longitudinally evaluate intracellular cytokines, in T1DM patients, and in subject at risk, by flow cytometry analysis. At T1DM onset we observed significantly lower percentage of peripheral CD4 + and CD8 + cells producing IFN-gamma in patients compared to controls and subjects at risk. The 15-month follow-up patients showed significantly lower percentage of CD4 + and CD8 + cells producing IFN-gamma compared to the other groups. At 8-year follow-up no significant differences were observed among the groups in the percentage of cells producing cytokines. We could have considered "exhausted cells" or these T cell subsets may be migrated from peripheral blood to pancreas. On the other hand, our results are in agreement with those reported in literature: in animal model the absence of IFN-gamma production makes beta-cells highly susceptible to viral infection and subsequent attack by natural killer cells, which lead to hyperglycaemia and diabetes mellitus.

Autoantibodies↗
PubMed2003

Antigen-specific T cell response in infants after recombinant hepatitis B virus vaccination at birth: evaluation of T helper lymphocyte diversity.

Recombinant hepatitis B virus antigen (rHBsAg)-specific CD4+ T cell clones (TCC) were isolated and expanded from the peripheral blood of nine children vaccinated at birth against the hepatitis B (HB) virus. Four of them responded with protective antibody production (responders), three subjects were unable to produce detectable antibody levels even after revaccination (nonresponders), and two infants produced antibodies only after revaccination (slow responders). TCC were then characterized for their ability to produce cytokines known to be important for T cell expansion (interleukin-2, IL-2) and/or effector functions (IL-4, IFN-gamma, IL-10). Results demonstrated that the frequency of rHBsAg-specific TCC in the samples of nonresponders was comparable to or higher than that in the samples of responders. Nevertheless, the majority of TCC obtained from responders or from slow responders before revaccination displayed the T helper 1 (T(H1))-dominant phenotype, while the majority of TCC obtained from nonresponders were nonpolarized T lymphocytes. After revaccination, the distribution of the different T(H) subsets in slow responders was heterogeneous. Overall, our present data suggest that an absence or delay in developing an rHBsAg-specific antibody response to vaccination is not associated with the capacity to generate an Ag-specific T cell response. However, compared to responders, nonresponding infants react to the rHBsAg vaccination with a reduced capacity to expand and differentiate toward polarized T(H) cells.

Cytokines↗
PubMed2002

Decline of maternal hepatitis A virus antibody levels in infants.

UNLABELLED: Hepatitis A is a common viral infection causing substantial morbidity and mortality. The anti-hepatitis A virus (HAV) vaccination in infants would guarantee control of the infection. However, the immunogenicity of the HAV vaccine in infants could be impaired by the presence of passively acquired maternal HAV antibodies. This study evaluated the prevalence of HAV antibodies in 103 women at delivery and in their babies in the first year of life. Eighteen mothers (17.5%) had anti-HAV serum level >10 mIU ml(-1). In their infants the anti-HAV level was still positive in 11 out of 18 (61.1%) at 12 mo. Two out of 85 infants born to anti-HAV-negative mothers and anti-HAV negative at birth were found to be positive at 5 mo of age. CONCLUSION: It is proposed that all women be screened at delivery for anti-HAV antibodies. Children born to anti-HAV-negative mothers could be vaccinated early during the first year of life, whereas vaccination could be postponed in children born to anti-HAV-positive mothers, if necessary.

Adolescent↗
PubMed2001

Mutations of CD40 gene cause an autosomal recessive form of immunodeficiency with hyper IgM.

CD40 is a member of the tumor necrosis factor receptor superfamily, expressed on a wide range of cell types including B cells, macrophages, and dendritic cells. CD40 is the receptor for CD40 ligand (CD40L), a molecule predominantly expressed by activated CD4(+) T cells. CD40/CD40L interaction induces the formation of memory B lymphocytes and promotes Ig isotype switching, as demonstrated in mice knocked-out for either CD40L or CD40 gene, and in patients with X-linked hyper IgM syndrome, a disease caused by CD40L/TNFSF5 gene mutations. In the present study, we have identified three patients with an autosomal recessive form of hyper IgM who fail to express CD40 on the cell surface. Sequence analysis of CD40 genomic DNA showed that one patient carried a homozygous silent mutation at the fifth base pair position of exon 5, involving an exonic splicing enhancer and leading to exon skipping and premature termination; the other two patients showed a homozygous point mutation in exon 3, resulting in a cysteine to arginine substitution. These findings show that mutations of the CD40 gene cause an autosomal recessive form of hyper IgM, which is immunologically and clinically undistinguishable from the X-linked form.

CD40 Antigens↗
PubMed2001

Increment of recombinant hepatitis B surface antigen-specific T-cell precursors after revaccination of slow responder children.

The aim of the study was to investigate the in vitro T-cell response to recombinant hepatitis B (rHBsAg) in a group of children (defined as "slow responders") vaccinated at birth, presenting antibody levels < 10 mIU/ml after the vaccination schedule, and developing anti-rHBs antibodies after revaccination. T-cell mediated immune response towards rHBsAg was evaluated in 35 healthy children in "bulk" culture experiments (19 responders and 16 slow responders) and by limiting dilution analysis (nine responders and five slow responders) to quantify the frequency of proliferating T lymphocyte-precursors (PTL-p). Before the booster dose, lymphocytes from slow responder children failed to proliferate to rHBsAg, while a normal proliferation was observed in all responders. A statistically significant difference in rHBsAg-specific PTLp frequencies was observed between the two groups. Among the slow responder group, a significant increase of PTLp was observed after the supplementary vaccine dose.Nevertheless, PTLp frequencies remained significantly lower than those measured in responders. These results suggest a role for follow-up of slow responder children over time, in order to perform booster vaccination when inadequate anti-HBs titre is present.

Hematopoietic Stem Cells↗
PubMed2000

Long term persistence of anti-HBs protective levels in young patients with type 1 diabetes after recombinant hepatitis B vaccine.

The aim of the present study was to evaluate the persistence of anti-hepatitis B protective levels in young patients with type 1 diabetes, successfully immunised with a recombinant hepatitis B vaccine. We re-evaluated, after a 4 year follow-up, 54 patients and 70 age and sex-matched healthy subjects. Protective antibodies levels were found in 50/54 (92%) patients and in 67/70 (96%) controls. Moreover, anti-HBs levels were similar in diabetic patients and controls (means of log-titre and (sd); 1.95 (0.88) and 2.18 (0.64) patients and controls, respectively; P=0.11). No cases of clinical hepatitis were reported and all patients and controls remained HBc negative. These data demonstrate the persistence of anti-HBs levels in children, adolescents and young patients with type 1 diabetes after recombinant hepatitis B vaccine showing evidence of longterm immunogenity and protective effect.

Adolescent↗
PubMed2000

Humoral response to recombinant hepatitis B virus vaccine at birth: role of HLA and beyond.

From 1991 to 1998 we vaccinated 4835 neonates against hepatitis B virus (HBV) and monitored their humoral response to the recombinant vaccine. In a sample of 184 of these babies we studied the association between HLA class I and II genomic polymorphisms and humoral response to the vaccine and the association between the response and immune-mediated diseases. A subgroup of 96 babies also underwent HLA class III (C4A and C4B) typing. Four levels of humoral response were identified, each with a peculiar MHC restriction. Different HLA products seem to act as agonists (C4AQ0 and HLA-DQB1(*)02) or antagonists (C4AQ0, HLA-DQB1(*)02, and HLA-DRB1(*)11, DQB1(*)0301) in lowering humoral response to HBV vaccine. The group of responders was characterized more for lacking "nonresponder" alleles than for having specific "responder" ones. Tolerance to HBV peptides may have clinical implications, possibly being a marker for babies with a genetic risk of immunopathologies. In fact, many of the poor responders carried from two to four HLA-DQ alpha beta heterodimers predisposing to insulin-dependent diabetes mellitus and celiac disease. Two true nonresponders suffered from allergies and two slow responders had transient episodes of hyperglycemia.

Alleles↗
PubMed2000

Rituximab (IDEC-C2B8): validation of a sensitive enzyme-linked immunoassay applied to a clinical pharmacokinetic study.

Rituximab is a chimeric monoclonal antibody (MAb) directed against the B-cell CD20 antigen that has been approved for therapy of relapsed and resistant follicular non-Hodgkin's lymphoma (NHL). This study describes the development and validation of a highly sensitive, rapid, accurate, precise enzyme-linked immunosorbent assay (ELISA) to measure Rituximab serum concentrations. This study also describes the application of the ELISA method to a pharmacokinetic study in a homogeneous group of patients with follicular lymphoma who received 4 weekly doses of MAb at the standard dose of 375 mg/m2 as consolidation of chemotherapy. In the patients in this study, the median Rituximab serum concentrations increased during therapy, and showed a slow decline during the posttreatment period. The Rituximab elimination half-life of approximately 20 days accounts for the demonstrated accumulation of MAb in serum samples. Because previous pharmacokinetic studies showed a correlation between Rituximab serum levels and tumor response, the ELISA method used in this study, which allows a precise control of serum concentrations, could be useful for predicting the final response to the MAb and for selecting patients able to benefit from higher dosage or repeated drug administration.

Antibodies, Monoclonal↗
PubMed2000

Immunophenotypic changes of fetal cord blood hematopoietic progenitor cells during gestation.

We measured cell surface expression of CD34, HLA-DR, CD38, CD19, CD33, CD71, and CD45 antigens in the hematopoietic progenitor cells of fetal cord blood to investigate immunophenotypic changes at different gestational ages. These antigens were identified by flow cytometry in 11 fetuses (gestational age 19-24 wk, in 12 preterm (25-28 wk) and in ten newborn infants born at term. The frequency and number of CD34+ cells were higher in the blood of the 11 fetuses; in addition, a statistically significant inverse correlation between number of CD34+ cells and advancing gestational age was noted. The numbers of CD34+ CD19+, CD34+ CD33+, and CD34+ CD45+ coexpressing cells were significantly higher in the fetuses, whereas CD34+ CD38+ cells were more represented in the neonates at term. Gestational age was inversely correlated with the number of CD34+ CD19+ and CD34+ CD33+ coexpressing cells. A positive correlation between gestational age and CD34+ CD38+ cells was noted. The number of CD34- CD19+, CD34- CD38+, and CD34- CD45+ cells was higher in term infants; furthermore, a significant correlation between advancing gestational age and CD34- CD38+ or CD34- CD45+ cells was demonstrated. The proliferative capacity was also higher at lower gestational ages. These data suggest that the development and lineage commitment of fetal cord blood hematopoietic progenitor cells are very active during the last two trimesters of pregnancy. The most significant changes of hematopoietic cells maturation seem to occur within 25 wk of gestation.

Antigens, CD↗
PubMed2000

Circulating GH isoforms and GH bioactivity in preterm neonates.

Among the molecular variants of human GH, the monomeric 22-kD is the predominant isoform, whereas the 20-kD is the second most abundant isoform. Because little is known on the pattern of human GH isoforms in the early postnatal period, we evaluated serum levels of 22-kD GH by an immunofluorometric assay and of 20-kD GH by an ELISA using an anti-20-kD antibody, and measured GH bioactivity with the Nb2 cell bioassay in 19 preterm neonates (gestational age, 32 +/- 0.5 wk; mean +/- SEM) on the fourth and 15th days of life. As control subjects, we studied 19 full-term neonates (gestational age, 39 +/- 0.3 wk) on the fourth day of life and 20 healthy adults, aged 20 +/- 0.3 y. Four-day-old preterm neonates showed significantly higher serum values of 20-kD GH (0.99 - 0.14 ng/mL) than full-term neonates (0.33 +/- 0.07 ng/mL; p < 0.001) and adults (0.09 +/- 0.02; p < 0.0001). Likewise, 22-kD GH and GH levels by Nb2 cell bioassay were also significantly higher (p < 0.001) in preterm than in full-term neonates and young adults. A significant decrease (p < 0.01) in 20-kD, 22-kD, and Nb2-determined GH was observed in preterm neonates on the 15th day of life The percentage of the 20-kD isoform was similar in the preterm infants at the fourth and 15th day, in full-term-infants, and in adults (2.7%, 2.7%, 2.8%, and 3.16%, respectively). Our results indicate that 20-kD GH serum levels change throughout life as regards total amount, but not as regards percentage.

Adult↗
PubMed1998

Enhancement of soluble CD23 serum levels and cell-surface CD23-expression in subjects at increased risk of type 1 diabetes mellitus and in diabetic patients.

The low affinity receptor for IgE, CD23, is expressed on lymphocytes among other cell types. The purpose of the present study was to assess serum sCD23 levels and CD23 expression on peripheral blood mononuclear cells (PBMC) in people at increased risk of developing Type 1 diabetes mellitus and in diabetic patients. Serum sCD23 levels were significantly higher in first-degree relatives of Type 1 patients (median: 3.2 U ml(-1)) (p < 0.001) and in newly diagnosed (median: 3.3 U ml(-1)) (p < 0.001) and long-standing (median: 2.5 U ml(-1)) (p = 0.01) Type 1 diabetic patients than in controls (median: 1.2 U ml(-1)). Newly diagnosed patients showed higher levels than those with long-standing disease (p = 0.026). Moreover the percentage of B cells expressing CD23 were significantly higher in first-degree relatives (median: 48.6%) (p < 0.001) and in newly diagnosed (median: 58%) (p < 0.001) and long-standing (median: 44.8%) (p = 0.03) Type 1 diabetic patients than in controls (median: 28.5%). The increased sCD23 levels and the increased number of cells expressing CD23 observed in subjects at increased risk of Type 1 diabetes and diabetic patients may be indicators of Th2 activity in Type 1 diabetes.

Adolescent↗
PubMed1998

Immunization with Haemophilus influenzae type b conjugate vaccine in children given bone marrow transplantation: comparison with healthy age-matched controls.

Forty-seven patients (age range, 7 months-18 years) with malignant (38 cases) and nonmalignant (9 cases) disorders given an allogeneic or an autologous bone marrow transplantation (BMT) were immunized with Haemophilus influenzae type b (Hib) polysaccharide-diphtheria toxoid conjugate vaccine administered in a single dose at different time points after transplantation. Results were compared with those of 13 healthy children matched for age and sex who received the same immunization schedule. Serum and saliva samples for measurement of total IgG subclass and specific antibody levels were obtained from patients and healthy controls before and 3 weeks after vaccination. Twenty-five of the 47 patients (53%) had a specific anti-Hib IgG response, while an effective IgA and IgM response was mounted by 23 (49%) and 11 (23%) children, respectively. In the control group, 13 of 13 subjects mounted a specific IgG antibody production (P < 0.005 in comparison to the patients' response rate), while an IgA and IgM response was demonstrated in 12 (92%; P < 0.01 compared to transplanted patients) and 7 (54%; P < 0.05 in comparison to BMT recipients) children, respectively. Lapse of time from BMT to immunization was the most important factor predicting antibody response, as proved by an effective increase in prevaccination specific IgG levels in the majority of patients vaccinated after 2 years from transplant. Our data demonstrate that BMT recipients have a reduced capacity to mount an antibody response to polysaccharide antigens compared to normal controls, even when a protein-conjugated vaccine is employed. Since time after transplant is the major factor influencing the recovery of immune reactivity to polysaccharide antigens, the ontogeny of the B cell repertoire seems to follow a predetermined sequential program of development.

Adolescent↗
PubMed1998

IL-10 and IL-4 co-operate to normalize in vitro IgA production in IgA-deficient (IgAD) patients.

In the present study we evaluated in vitro immunoglobulin production from IgAD individuals and healthy controls. Peripheral blood mononuclear cells (PBMC) from IgAD and controls were cultured with anti-CD40 MoAb presented on a CDw32-transfected fibroblast cell line (CD40 system) in the presence of IL-10, IL-2, IL-4, transforming growth factor-beta (TGF-beta) alone as well as of IL-10 in combination with each of the other three cytokines. Only IL-10 added alone induced significant changes in baseline immunoglobulin production; marked increases in median supernatant levels of all three isotypes were observed in both groups. The most striking finding of this study was the synergizing effect of IL-4 on IgA production in the IgAD group when added with IL-10; median IgA supernatant level increased to a value superimposable on that found in the normal controls which remained about the same as when stimulated with IL-10 alone. The synergic effect of IL-4 and IL-10 was specific to the IgA isotype.

Adolescent↗
PubMed1998

Placental transfer favours high avidity IgG antibodies.

The aim of the present study was to evaluate if maternal-foetal antibody placental transfer may be affected by antibody avidity. We compared the avidity index (AI) of IgG antibodies to tetanus toxoid (TT) and to type 3 pneumococcal antigen (Pn) in cord blood of 10 healthy term and 8 preterm infants and in their mothers' sera at delivery. In order to evaluate whether a heavier antigenic exposure may influence the placental transfer, we also studied 15 Pakistani maternal sera and cord blood pairs. TT- and Pn-specific antibody AI was significantly higher in Italian and Pakistani term infants than in their mothers, while a significant difference in specific TT antibody AI, but not in specific Pn antibody AI was observed between preterm infants and their mothers. Italian and Pakistani cord blood/maternal serum pairs showed comparable values of AI. Our data suggest that high avidity antibodies preferentially cross the placenta; this seems to start early during gestation and appears to be related to the nature of the antigen to which the antibodies are directed, but not to the degree of antigenic exposure.

Antibody Affinity↗
PubMed1997

Celiac disease.

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Celiac Disease↗