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V Lampasona

Publications and source records attributed to V Lampasona.

At least 19 recordsLinked to original sources
PubMed2005

No evidence of diabetes-specific CD38 (ADP ribosil cyclase/cyclic ADP-ribose hydrolase) autoantibodies by liquid-phase immunoprecipitation.

AIMS/HYPOTHESIS: Autoantibodies to the ADP ribosyl cyclase/cyclic ADP-ribose hydrolase CD38 have been suggested to be markers of autoimmunity in Type 1 and Type 2 diabetes. The aim of this study was to develop a fluid phase assay for population screening. METHODS: Human recombinant CD38 was cloned and expressed by in vitro transcription and translation for fluid phase radio-binding assay, as a fusion protein in COS7 cells for fluid phase immunoprecipitation, and as a fusion protein for western blot assays. Antibody binding to each recombinant protein was measured in sera from patients with Type 1 diabetes, Type 2 diabetes and control subjects. RESULTS: Immunoprecipitation of radio-labelled in vitro transcribed and translated CD38 was low in all sera, including monoclonal anti-CD38 antibodies, with no difference between patients and control subjects. Monoclonal antibodies to CD38, but not patient or control sera immunoprecipitated recombinant CD38 fusion protein expressed in COS7 cells. Antibody binding to recombinant CD38 in solid-phase western blot assay was detected in sera from 2% of patients with Type 1 diabetes, 6% of patients with Type 2 diabetes, and 8% of control subjects. CONCLUSIONS: This study failed to detect diabetes relevant binding of antibodies to recombinant CD38 using liquid-phase methods. Formal comparison of anti-CD38 antibody detection between laboratories is suggested.

ADP-ribosyl Cyclase↗
PubMed2004

Similar low frequency of anti-MOG IgG and IgM in MS patients and healthy subjects.

The authors used a liquid-phase radiobinding assay to measure serum anti-myelin oligodendrocyte protein (MOG) immunoglobulin (Ig) G in 87 patients with multiple sclerosis (MS), in 12 patients with encephalomyelitis, and in 47 healthy subjects. Anti-MOG IgM was determined in samples obtained at onset from 40 of 87 patients with MS and in control subjects. The frequency of positive samples with low titers of anti-MOG IgG (< or =5.7%) and IgM (< or =8.3%) was similar in all the groups and subgroups. Binding competition experiments showed that these antibodies had low affinity. Anti-MOG antibodies are not disease specific.

Adolescent↗
PubMed2004

Immune responses to glutamic acid decarboxylase and insulin in patients with gestational diabetes.

Pregnancy is a natural state of immunoprotection and tolerance. We studied subjects with gestational diabetes (GDM) to evaluate the influence of pregnancy on the humoral immune response to the autoantigen GAD and to injected insulin. Antibodies against glutamic acid decarboxylase (GADA) subclasses and epitope reactivity were determined in 34 GADA-positive pregnant patients with GDM, in 20 GADA-positive relatives of people with TID and in 25 GADA-positive patients with newly diagnosed TID. Partum levels of insulin antibodies (IA), IgG1- and IgG4-IA were measured in 131 women with GDM treated with human insulin from the time of diabetes diagnosis (including 22 with GADA) and were compared to 19 patients with TID after 3 months of insulin treatment. GADA titre and subclasses were similar among all groups. GADA in GDM patients bound fewer epitopes than GADA in relatives of patients with TID (all epitopes being present in 23%versus 65%, P < 0.01). In particular, antibodies to the minor GADA epitopes GAD6596-249, GAD651-100 and GAD67 were less frequent in patients with GDM compared to relatives (P < 0.01). Antibodies to insulin (IA) were found in 17% of patients with GDM. They were more frequent in GDM patients with GADA compared to GADA-negative patients (41%versus 12%, P < 0.005). IgG1 was the dominant insulin antibody subclass response in both patients with GDM and TID but levels of IgG1-IA and IgG4-IA were significantly lower in patients with GDM compared to patients with TID (P < 0.004). Antibody responses in women with gestational diabetes appear to be dampened and restricted, but without change in subclass usage.

Adolescent↗
PubMed2000

Maturation of the humoral autoimmune response to epitopes of GAD in preclinical childhood type 1 diabetes.

GAD is a major target of autoimmunity in preclinical type 1 diabetes. Here we examine the maturation of the humoral response to GAD epitopes sequentially from birth to diabetes onset or current follow-up in 29 GAD antibody (GADA)+ offspring of parents with diabetes from the BABYDIAB Study. Antibodies were measured against GAD65, GAD67, and GAD65/67 chimeras by radiobinding assay. In 28 of 29 offspring, the first GADAs contained reactivity against epitopes within GAD65 residues 96-444, suggesting that the middle GAD65 region is a primary target of GAD humoral autoimmunity. In 7 of these 28 offspring, initial antibody reactivity was against all epitope regions tested (middle GAD65, COOH-terminal GAD65 residues 445-585, NH2-terminal GAD65 residues 1-95, and GAD67); in 16 offspring, reactivity was to middle and COOH-terminal GAD65 epitopes, and in 5 offspring, reactivity was only to the middle GAD65 epitopes. The single offspring without middle GAD65 reactivity had antibodies to the NH2-terminal epitopes in the absence of all other islet autoimmunity. Subsequent GADA epitope spreading was frequent and seen in 10 of 15 offspring with informative follow-up samples. Spreading was mostly (eight cases) to NH2-terminal GAD65 epitopes. In two offspring, spreading to new epitopes was found when antibody titers to GAD65 and early epitopes were declining, suggesting determinant-specific regulation of the humoral response. None of the GADA reactivities nor any changes in reactivity over time were specifically associated with diabetes onset. The findings suggest that the humoral autoimmune response to GAD found in childhood is dynamic, is initially against epitopes within the middle portion of GAD65, and spreads to epitopes in other regions of GAD65 and GAD67.

Antibody Formation↗
PubMed1999

Comparison of tissue transglutaminase-specific antibody assays with established antibody measurements for coeliac disease.

Tissue transglutaminase C has recently been identified as one of the auto-antigens of endomysial antibodies found in coeliac disease. In this study we have cloned the human autoantigen and developed immunoassays measuring antibodies to transglutaminase in order to compare their diagnostic performance to that of established markers of the disease. A radiobinding assay using in vitro transcribed and translated 35S-methionine-labelled transglutaminase detected IgG antibodies in 110 and IgA antibodies in 109 of 112 patients at diagnosis of coeliac disease and in three and four of 92 control subjects, respectively. A radiobinding assay measuring both IgG and IgA transglutaminase antibodies identified 111 (99.1%) of the patients and 4 (4.3%) control subjects. Concordance of this assay with the IgA endomysial antibody test was found in 108 patients and 89 control subjects: two patients who had IgA deficiency and a third patient without IgA deficiency were only detected in the radiobinding assay; one patient had weak IgA endomysial antibodies only, and three of the control subjects with weak transglutaminase antibodies by radiobinding assay were undetectable in the IgA endomysial antibody assay. IgA and IgG ELISA using guinea pig transglutaminase and commercial ELISA measuring anti-gliadin antibodies had lower sensitivity and specificity than the radiobinding assays or the IgA endomysial antibody assay. This study confirms tissue transglutaminase C as a major autoantigen in coeliac disease and describes novel radiobinding assays for large scale testing to identify cases of coeliac disease.

Adolescent↗
PubMed1999

Antibodies to tissue transglutaminase C in type I diabetes.

AIMS/HYPOTHESIS: Silent coeliac disease is a gluten driven autoimmune disease which is relatively frequent in patients with Type I (insulin-dependent) diabetes mellitus. To determine the extent of gluten associated autoimmunity in Type I diabetes, autoantibodies to tissue transglutaminase C, a major autoantigen in coeliac disease, were measured in patients with new-onset Type I diabetes. METHODS: We measured IgG and IgA tissue transglutaminase C autoantibodies using human recombinant antigen and radio-binding assays in a cohort of 287 patients with new-onset Type I diabetes, 119 with Type II (non-insulin-dependent) diabetes mellitus and in 213 control subjects. RESULTS: We found IgA and IgG tissue transglutaminase C antibodies in 24 (8 %) patients with Type I diabetes; 97 (33 %) patients had IgG antibodies only and 1 IgA antibodies only. Antibody concentrations were highest in those with both IgA and IgG antibodies. Only 2 (2 %) patients with Type II diabetes and 2 (1 %) control subjects had either IgG or IgA tissue transglutaminase C antibodies. Patients with HLA DRB1(*)04 alleles had the highest prevalence of IgG tissue transglutaminase C antibodies. CONCLUSION/INTERPRETATION: These data show that almost 10 % of patients have autoimmunity typical of coeliac disease and that another 30 % have low level tissue transglutaminase C antibody binding. This high prevalence suggests either involvement of the gut in the pathogenesis of Type I diabetes or that transglutaminase is a secondary autoantigen resulting from beta-cell destruction. [Diabetologia (1999) 42: 1195-1198]

Adolescent↗
PubMed1998

Early development and spreading of autoantibodies to epitopes of IA-2 and their association with progression to type 1 diabetes.

Autoimmunity precedes clinical type 1 diabetes, and indicators of maturing autoimmune responses may be useful markers for disease prediction. To study this, epitope maturation of autoantibodies to the related protein tyrosine phosphatase (PTP)-like autoantigens IA-2 and IA-2beta was examined in sequential samples from birth in a cohort of 21 offspring developing multiple islet autoantibodies and a similar cohort of 48 relatives of patients with type 1 diabetes recruited at an older age. Initial reactivity in offspring was heterogeneous against the IA-2 juxtamembrane region (10/21) and PTP domains (13/21), and both specificity and extent of initial IA-2/IA-2beta autoantibodies were associated with HLA class II genotype. Intra-IA-2 epitope spreading and/or intermolecular spreading to IA-2beta epitopes were observed in seven offspring. In contrast, in older relatives, IA-2/IA-2beta Ab reactivity was stable and spreading rare. Development of diabetes in children was associated with the presence of Abs to the IA-2 juxtamembrane region (risk by age 5 yr, 52% vs 0% in those with PTP domain Abs only; p < 0.02), and 5 of 26 relatives who developed diabetes had IA-2 Abs only against the juxtamembrane region. The findings show that autoantibody reactivity to IA-2/IA-2beta is dynamic in the young, show that the juxtamembrane region of IA-2 is an early IA-2 autoantibody target, and suggest that these Abs are a risk factor for development of type 1 diabetes in infancy.

Adult↗
PubMed1998

IA-2 (islet cell antigen 512) is the primary target of humoral autoimmunity against type 1 diabetes-associated tyrosine phosphatase autoantigens.

IA-2 (islet cell Ag 512) and IA-2 beta (phogrin/IAR) are related autoantigens associated with type 1 diabetes. To determine the critical regions for autoantibody binding and which of these autoantigens is the primary target, mutant and chimeric constructs were used to characterize Ab epitope binding in sera from 217 new onset patients with type 1 diabetes and sequential samples from 141 islet cell Ab positive first degree relatives of patients. All 22 relatives and 121 of 129 patients with IA-2/IA-2 beta Abs had reactivity to IA-2-specific epitopes. These epitopes were in the juxtamembrane region (residues 601-682) and the protein tyrosine phosphatase (PTP)-like domain of IA-2. Chimeras showed that IA-2 residues 795-889 were important for IA-2-specific Ab binding in the PTP-like domain, and mutation of IA-2 residues 877 and 911, previously indicated as relevant for phosphatase activity, also reduced Ab binding. In contrast, Ab binding to IA-2 beta was limited to its PTP-like domain, most IA-2 beta Abs recognized epitopes shared with IA-2, and only 20 patients and 2 relatives had Abs to IA-2 beta-specific epitopes. In 4 relatives, IA-2 and/or IA-2 beta Abs developed in follow-up samples. In each of these, Abs to IA-2-specific epitopes were the first detected. In three, spreading to epitopes shared between IA-2 and IA-2 beta in subsequent samples was seen. In the 17 relatives who developed type 1 diabetes, progression to disease was associated with reactivity to multiple IA-2/IA-2 beta epitopes. These data suggest that IA-2 is the primary phosphatase-like autoantigen associated with type 1 diabetes and that studying autoantibody epitope diversity may assist in disease prediction.

Adolescent↗
PubMed1998

Humoral and cellular immune parameters before and during immunosuppressive therapy of a patient with stiff-man syndrome and insulin dependent diabetes mellitus.

OBJECTIVES: Humoral and cellular immune reactivity are reported for two neuroendocrine autoantigens-glutamic acid decarboxylase (GAD) and the protein tyrosine phosphatase IA-2-in a patient with the autoimmune type of stiff-man syndrome and insulin dependent diabetes (IDDM). METHODS: Antibodies and T cell proliferation against GAD and IA-2 and cytokine release of antigen stimulated T cells (IFN-gamma) were determined before and several times during immunosuppressive therapy with prednisolone. RESULTS: Raised GAD antibodies against full length GAD65 or chimeric constructs were detected before therapy and they remained at a high concentration despite a marked clinical improvement during cortisone treatment. Antibodies to IA-2 were undetectable, but weak T cell responses to both GAD and IA-2 were seen before therapy and once on reduction of high cortisone dosages when the patient showed signs of clinical deterioration. Cytokine profiles showed increased IFN-gamma production after stimulation with GAD or IA-2 suggesting increased activation of TH1 cells. CONCLUSION: Immunosuppressive therapy --even with extremely high doses of 500 mg a day--does not lead to the reduction of antibody concentrations in the periphery nor to a switch in epitope recognition of such antibodies despite clinical improvement. The amount of T cell reactivity to various antigens, however, may be a useful marker to monitor the effectiveness of immunotherapy.

Autoantibodies↗
PubMed1997

Lack of association of DMB polymorphism with insulin-dependent diabetes.

Considerable evidence exists that the genes coding for the HLA class II DQ molecules in the MHC region are major contributors to genetic susceptibility in insulin-dependent diabetes. Located centromeric to the DQ loci are the genes encoding DMA and DMB, two class II-like molecules which play an essential role in the pathway leading to antigen presentation by HLA class II. In this study we have examined the distribution of the DMB allele and studied HLA DQA1-DQB1-TAP2-DMB haplotypes in 52 IDDM families and 65 un-related controls. DMB allele frequencies in IDDM and control subjects were not significantly different. DMB*0101 was present in 85% of patients vs. 76% of controls, DMB*0102 in 12 vs. 17%, DMB*0103 in 3 vs. 5%, DMB*0104 in 0 vs. 2%. The IDDM-susceptible MHC DQA1-DQB1 haplotypes found by analysis of IDDM families were not associated with specific DMB alleles. We conclude that the described DMB polymorphisms are not associated with IDDM susceptibility and DMB genotyping is unlikely to improve the assessment of genetic risk for IDDM.

Alleles↗
PubMed1996

Autoantibodies in insulin-dependent diabetes recognize distinct cytoplasmic domains of the protein tyrosine phosphatase-like IA-2 autoantigen.

Protein tyrosine phosphatase-like IA-2 is a major autoantigen in insulin-dependent diabetes. It has been identified as both a specificity of cytoplasmic islet cell Abs and one of the precursors of the 40- and 37-kDa tryptic fragment islet autoantigens. To characterize autoantibody binding to IA-2 and determine whether humoral autoimmunity extends to other tyrosine phosphatases, we analyzed serum reactivity in 100 patients with insulin-dependent diabetes against different in vitro translated portions of the IA-2 protein as well as the tyrosine phosphatase domains of HPTPbeta and HPTPdelta. All autoantibody reactivity was confined to the cytoplasmic portion of IA-2 (amino acids 601-979). At least four epitopes were found. These were contained within amino acids 605 to 620 and 605 to 682 of the juxtamembrane region and within amino acids 777 to 937 and 687 to 979 in the IA-2 tyrosine phosphatase-like domain. Footprinting studies confirmed the presence of multiple epitopes. Fifty-six percent of sera with IA-2 Abs bound epitopes within the juxtamembrane region, and 83% bound epitopes in the tyrosine phosphatase-like domain; 39% had Abs to both regions. No reactivity against the IA-2 ectodomain or the tyrosine phosphatase domains of HPTPbeta and HPTPdelta was found. These data suggest that the cytoplasmic region, in particular the tyrosine phosphatase-like domain, is the major target of IA-2 Abs in insulin-dependent diabetes, and that autoantibody reactivity is specific for IA-2 or IA-2-like molecules.

Adolescent↗
PubMed1996

Association of IA-2 autoantibodies with HLA DR4 phenotypes in IDDM.

Insulin, glutamate decarboxylase (GAD) and the protein tyrosine phosphatase-like molecule IA-2 are major targets of humoral autoimmunity in insulin-dependent diabetes mellitus (IDDM). These autoantibodies are heterogeneous with respect to age and patient human leukocyte antigen (HLA) phenotype. We have previously demonstrated that GAD and IA-2 antibodies potentially identify different subsets of IDDM patients. The aim of this study was to determine whether GAD and IA-2 autoantibodies were associated with different HLA DR phenotypes. We studied 160 patients with IDDM onset before age 16 years. At disease onset serum was tested for GAD and IA-2 antibodies by immunoprecipitation by in vitro-translated 35S-methionine labelled recombinant proteins. IA-2 antibodies were significantly associated with HLA DR4: 67 (86%) of 78 patients with HLA DR4 vs 31 (38%) of 82 non-DR4 patients had IA-2 antibodies (Pc < 0.0001) and IA-2 antibody levels were higher in patients with HLA DR4 (Pc < 0.0001). In contrast, GAD antibodies were more prevalent (Pc < 0.05) and antibody levels highest (Pc < 0.01) in patients with HLA DR3 phenotypes. These data provide further evidence that, in IDDM, production and titre of major autoantibody specificities are associated with HLA class II alleles.

Alleles↗
PubMed1995

Identification of protein tyrosine phosphatase-like IA2 (islet cell antigen 512) as the insulin-dependent diabetes-related 37/40K autoantigen and a target of islet-cell antibodies.

The majority of patients with insulin-dependent diabetes (IDDM) have Abs to 40- and/or 37-kDa tryptic fragments (37/40K-Abs) deriving from an unidentified islet cell membrane protein distinct from glutamate decarboxylase (GAD). Recently, autoantibodies against ICA512, which has identity with the protein tyrosine phosphatase-like protein IA2, were reported. In this study we have examined whether IA2/ICA512 is the Ag specificity of 37/40K-Abs, and one of the determinants of islet cell Abs (ICA) detected by immunofluorescence. Serum from 51 of 100 new onset IDDM patients immunoprecipitated 40- and/or 37-kDa insulinoma polypeptides, and 53 immunoprecipitated in vitro translated rIA2; 49 had both 37/40K-Abs and rIA2 Abs. There were strong correlations between the levels of Abs to rIA2 and both 40 kDa (r = 0.85, p < 0.0001) and 37 kDa (r = 0.70, p < 0.0001) insulinoma polypeptides. Trypsin treatment of immunoprecipitated rIA2 yielded 40- and 37-kDa fragments, and preincubation of sera with rIA2 completely inhibited binding to the insulinoma 40- and 37-kDa polypeptides. IA2 Ab levels also correlated with ICA titer in GAD-Ab negative sera, and preincubation with rIA2 reduced ICA staining intensity in sera with ICA and IA2 Abs, but not in sera with ICA in the absence of IA2 Abs. These results provide clear evidence for the identification of IA2/ICA512 as the precursor of the islet 40- and 37-kDa polypeptide autoantigens and as one of the ICA specificities. Combined detection of Abs to IA2 and GAD65 in a single radio-binding assay identified Abs in 88 of 100 IDDM patients, and potentially facilitates population screening for IDDM risk assessment.

Adolescent↗
PubMed1995

HLA DQA1-DQB1-TAP2 haplotypes in IDDM families: no evidence for an additional contribution to disease risk by the TAP2 locus.

The TAP2 gene, located in the HLA class II region, encodes a subunit of a transporter involved in the endogenous antigen-processing pathway, and has been suggested to contribute to the genetic risk for insulin-dependent diabetes (IDDM). In order to determine whether the TAP2 locus modulates the risk conferred by HLA DQ loci, HLA DQA1-DQB1-TAP2 haplotypes were analysed in 48 IDDM probands, their first degree relatives, and in 62 normal control subjects. A decreased frequency of the TAP2B allele was confirmed in this IDDM cohort (12 vs 28% in control subjects, pc < 0.05). Analysis of 73 informative meiotic events in IDDM and control families demonstrated a recombination fraction between HLA DQB1 and TAP2 loci of 0.041 (Log of the odds score = 16.5; p < 10(-8)) indicating strong linkage between these loci. Family haplotype analysis demonstrated linkage disequilibrium between TAP2 and HLA DQA1-DQB1, and showed that the reduced frequency of TAP2B was associated with its absence on the IDDM susceptible DQA1*0301-DQB1*0302 haplotype, its low frequency on DQA1*0501-DQB1*0201, and the association of TAP2B with DQA1*0101-DQB1*0501 haplotypes which were less frequent in IDDM patients. Comparison of transmitted with non-transmitted haplotypes in IDDM families showed a slight but not significant decrease in TAP2B allele frequency on transmitted (3 of 37) vs non-transmitted (2 of 9) HLA DQA1*0501-DQB1*0201 haplotypes. No other differences were observed. Twenty-four unrelated DQA1*0501-DQB1*0201 haplotypes from non-diabetic families had a TAP2B allele frequency (4%) similar to that in IDDM haplotypes.(ABSTRACT TRUNCATED AT 250 WORDS)

ATP Binding Cassette Transporter, Subfamily B, Mem↗