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I R Mackay

Publications and source records attributed to I R Mackay.

At least 109 records · Page 6Linked to original sources
PubMed1994

Contemporary concepts of immunological function.

The science of Immunology, since its beginnings around the year 1900, has expanded to encyclopaedic dimensions and has had enjoyed two "golden ages," in the early 1900s and after the 1950s. By way of illustration, as many as 23 of the present total of 157 Nobel Laureates received their award for discoveries relevant to immunology, including the first in 1901 to Emil von Behring for the use of immune serum in the treatment of disease. The Nobel awards in Immunology will be used as theme points for the text of this lecture. In fact, this paper asks you to imagine a series of six lectures on Contemporary Concepts delivered at various times between 1900 and the present, specifically 1905, 1930, 1960, 1970, 1980 and today, May 1994.

Allergy and Immunology↗
PubMed1993

Autoreactive MHC-restricted cytotoxic cells in BALB/c mice after novel immunisation with a conserved mammalian autoantigen.

We investigated whether a novel immunisation scheme using an endogenous protein could stimulate an autoreactive cytolytic response. The protein selected was porcine dihydrolipoamide dehydrogenase, the E3 component of the mitochondrial 2-OADC enzyme family, because it is structurally conserved in mammals and ubiquitously expressed. Recombinant insulin was used as an alternative antigen. Female BALB/c mice were injected with adjuvant-free syngeneic lymphoid cells that had been exposed to E3 in hypertonic medium to facilitate its pinocytosis and were given two booster injections. Effector lymphoid cells from immunised mice were cultured in vitro with irradiated syngeneic cells that had been treated with hypertonic medium, either with or without antigen. Cytolytic effector cells were detected that lysed isogeneic and not allogeneic target cells, but only from mice immunised with E3. This experimental system provides a new model for the early stages of the development of autoimmunity.

Animals↗
PubMed1993

Subclasses of immunoglobulins and autoantibodies in autoimmune diseases.

The differing capacity of subclasses of IgG to bind to protein A and protein G was used in a sequential affinity purification procedure to examine immunoglobulin isotypes and subclasses in autoimmune disease. The utility of the procedure is that affinity-purified fractions containing particular isotypes and subclasses of immunoglobulin can be analyzed for their content of autoantibodies using standard techniques. For each of four autoimmune diseases studied, chronic active hepatitis, Sjogren's syndrome, primary biliary cirrhosis, and rheumatoid arthritis, there were characteristic protein elution profiles and the various disease-specific autoantibodies showed preferential distributions among the isotypes and subclasses. Moreover there was not an absolute correlation between an increased level of a particular subclass and the occurrence of antibodies of that subclass. The occurrence of highly disease-specific immunoglobulin subclass profiles suggests that the hypergammaglobulinemia associated with autoimmunity cannot be attributed entirely to polyclonal B-cell activation. Rather, there are disease-specific alterations in isotype subclass switching which may reflect different cytokine-dependent influences on autoimmune B cells and their products.

Antibody Specificity↗
PubMed1993

Molecular detection of interferon-alpha expression in multiple sclerosis brain.

The demonstration of intermittent interferonaemia in patients with multiple sclerosis prompted a molecular analysis of brain tissue for expression of interferon-alpha genes. A sensitive method was developed based on the polymerase chain reaction. Primer sets were used that could amplify all interferons-alpha or two particular subtypes, interferon-alpha 2 and interferon-alpha 4. The procedure was successful in detecting expression of interferons-alpha in brain and non-brain tissues in most patients with multiple sclerosis. However, expression was demonstrable also in a similar proportion of patients with other neural diseases, and patients with other illnesses. The data indicate that there can be constitutive expression of interferons-alpha in brain tissue, but the possibility that this becomes amplified in multiple sclerosis was not revealed by this study.

Adolescent↗
PubMed1993

HLA-DQ genotypes are associated with autoimmunity to glutamic acid decarboxylase in insulin-dependent diabetes mellitus patients.

This study has investigated the genetic basis of the heterogeneous autoimmune response to glutamic acid decarboxylase (GAD) in 179 Australian patients with IDDM. Antibodies to GAD have been correlated with HLA-DQB1 alleles and genotypes, as determined by sequence-specific oligonucleotide hybridizations after polymerase chain reaction was applied to exon 2 of the DQ beta 1 gene. HLA-DQ2 was significantly increased (p < 0.01) in IDDM patients with antibodies to GAD. Antibodies to GAD were detected in 64% of 72 DQ2.8 patients, in 55% of 29 DQ2.2 or DQ8.8 patients and in 41% of 78 patients with other HLA-DQB1 genotypes. HLA-DQ genotype association with autoimmunity to GAD was statistically significant (p = 0.02) and reflected early formation of antibodies to GAD, rather than an HLA association with persistence of antibodies to GAD, since the genotype effect was more evident (p = 0.02) in those with more recent onset (0-5 years) of IDDM. Also, the HLA-DQ genotype effect was more evident in patients with IDDM onset after the age of 14 years (p = 0.003). Multivariate analysis showed that HLA-DQB1 genotypes had a more significant impact on antibodies to GAD than either duration or age of onset of IDDM. In patients with IDDM in childhood, only a minority had low-risk HLA-DQB1 genotypes (37%) when compared with those with onset in adulthood (62%) (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Cicaprost, an orally active prostacyclin analogue: its effects on platelet aggregation and skin blood flow in normal volunteers.

1. Prostacyclin (PGI2) and its analogues may be useful in peripheral vascular disease. However, most have to be given intravenously due to their metabolic instability. 2. We have investigated the pharmacological effects of cicaprost, a synthetic PGI2 analogue which is metabolically stable and bioavailable after oral administration, in eight healthy male volunteers. 3. This was a double-blind, placebo-controlled, cross-over study. The volunteers were given either placebo, 5 micrograms, 7.5 micrograms or 10 micrograms cicaprost (at 09.00 h, 14.00 h, 19.00 h and again at 09.00 h the following day) on four separate occasions each 14 days apart. 4. Platelet aggregation induced by collagen and ADP in platelet rich plasma (PRP) and whole blood were measured prior to and 1 h after the trial medication. Laser Doppler flowmetry measured skin blood flow on the face before and after medication. 5. There was a statistically significant dose relationship in the inhibition of platelet aggregation induced by 2 microM ADP and 0.4 microgram ml-1 collagen in PRP and 2 microM ADP and 0.6 microgram ml-1 collagen in whole blood by cicaprost (P = 0.008, P = 0.34, P = 0.011 and P = 0.036, respectively). The threshold dose was 7.5 micrograms. Attenuation of anti-platelet effects was seen with the 14.00 h and 19.00 h doses. This may be due to a decrease in absorption after meals or to the development of tachyphylaxis. 6. Similar dose dependent effects of cicaprost on skin blood flow were also found (P = 0.01 and P = 0.006 for maximum output signal and red blood cell flux, respectively). The threshold dose was 7.5 micrograms. 7. In conclusion, cicaprost has significant anti-platelet and vasodilatory effects when given in doses of 7.5 micrograms and 10 micrograms three times a day in healthy male volunteers.

Adult↗
PubMed1993

Antibody to two forms of dihydrolipoamide acetyltransferase (PDC-E2) in primary biliary cirrhosis.

Dihydrolipoamide acetyltransferase, the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2), is the major autoantigen in primary biliary cirrhosis. By immunoblotting with sera from patients with primary biliary cirrhosis, we observed a double band, of molecular weight 70 and 74 kD for PDC-E2, when a preparation of bovine heart mitochondria was not boiled prior to electrophoresis. This double band could also be detected using antisera raised in rats or rabbits against intact PDC or PDC-E2, but not in antisera raised against a synthetic decamer representing the lipoic acid binding sequence of PDC-E2; the latter reacted only with the 74 kD component. Antibody eluted from either the 70 or 74 kD component reacted with both 70 and 74 kD components. By ELISA, sera from patients with primary biliary cirrhosis reacted more strongly with a non-boiled than a boiled PDC-E2, whereas immune animal sera reacted equally with both preparations. Thus, according to whether preparations of PDC are boiled or not, two conformationally alternative forms of the PDC-E2 protein can be revealed by immunoblotting. The two forms in non-boiled preparations migrate at molecular weights corresponding to 70 and 74 kD.

Acetyltransferases↗
PubMed1993

Antibodies to glutamic acid decarboxylase in Australian children with insulin-dependent diabetes mellitus and their first-degree relatives.

Antibodies to glutamic acid decarboxylase (GAD), previously known as the 64-kD pancreatic islet cell autoantigen, are an important serologic marker of insulin-dependent diabetes mellitus (IDDM). Antibodies to GAD (anti-GAD) were examined in sera from Australian children with newly diagnosed IDDM (within 1 mo of diagnosis), IDDM of longer duration (mean +/- SD, 4.8 +/- 3.3 y), and in first-degree relatives, using a radioimmuno-precipitation assay with purified porcine brain GAD as antigen. Antibodies to islet cell cytoplasmic antigens (ICAb) were tested concurrently. The frequency of anti-GAD was not significantly different in children with newly diagnosed IDDM (31 of 42, 74%) and with IDDM of longer duration (14 of 21, 67%), whereas ICAb were present more frequently in children with newly diagnosed IDDM (64%) than in those with longer duration IDDM (14%). In all, 90% of children with newly diagnosed IDDM had either anti-GAD or ICAb, whereas only 48% had both. For the 77 first-degree relatives, the frequency of anti-GAD was 2% (one of 44) in parents and 6% (two of 33) in siblings; ICAb were not detected in any of these relatives. The presence of anti-GAD in the majority of children with IDDM, irrespective of the duration of their disease, represents a useful diagnostic marker for IDDM, and should be of value in ascertaining individuals at risk for developing IDDM.

Adolescent↗
PubMed1993

Antibodies to glutamic acid decarboxylase reveal latent autoimmune diabetes mellitus in adults with a non-insulin-dependent onset of disease.

The classification of adults with diabetes mellitus can be invalidated by patients who initially present as NIDDM but who later become frankly insulin dependent. In some of these, the pathogenesis could be similar to that in IDDM, namely autoimmune destruction of the pancreatic beta-cells. We studied 102 patients > 35 yr of age at diabetes onset who had initially been nonketotic and non-insulin-dependent for > or = 6 mo. They were classified according to glucagon-stimulated C-peptide levels into an insulin-deficient group (n = 33) and a non-insulin-deficient group (n = 69). We measured antibodies to GAD, islet cell cytoplasm, thyroid antigens, and gastric parietal cells in both groups. Anti-GAD was significantly higher in the insulin deficient group, 76% (25 of 33), than in the non-insulin deficient group, 12% (8 of 69), and this difference was substantially greater than that shown for ICAs. Thus, in a proportion of adults who present with NIDDM, a slowly evolving autoimmune insulitis can be revealed by testing for anti-GAD. This could have important connotations not only for early intervention, but also for the correct classification of diabetes.

Adult↗
PubMed1992

Mitochondrial DNA mutation associated with aging and degenerative disease.

Previous theories of aging based on somatic mutation neglected mtDNA, which has a high propensity for mutational error. Knowledge of yeast mtDNA mutations and their functional effects, and of human mtDNA mutations identified in the mitochondrial cytopathies, provides for a concept of aging based on the cumulative effect of mutations affecting human mtDNA. An essential feature of this concept is heteroplasmy, representing mixtures of normal and mutant mtDNA at the cellular and mitochondrial level, resulting in a "tissue mosaic" of focal bioenergetic deficits. Direct evidence for the concept is provided by (i) focal loss of staining for mitochondrially encoded enzymes, such as cytochrome c oxidase, in tissues of aged individuals (humans and rats) and (ii) an age-related increase in deletional mutations in mtDNA demonstrable by application of the polymerase chain reaction to DNA templates from individuals of different ages.

Aging↗
PubMed1992

Antiproliferative potencies of interferons on melanoma cell lines and xenografts: higher efficacy of interferon beta.

BACKGROUND: Human melanomas have shown only limited responsiveness to clinical therapy with interferon (IFN). PURPOSE: Our aim was to determine the most effective class of IFN for inhibiting growth of melanoma cells and to establish whether variation exists in response of various cell lines to different IFNs. METHODS: We compared the direct antiproliferative effects of the type I IFN alpha-2b, IFN alpha-4a, and IFN-beta and the type II IFN-gamma on eight melanoma cell lines grown in vitro. We did this comparison by determining the concentration of each IFN that resulted in 50% growth inhibition, using the MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium tetrazolium bromide] dye uptake method. We also tested IFN alpha-2a and IFN-beta for their ability to inhibit the growth of xenografts of the LiBr melanoma cell line in vivo in nude mice. Receptor binding was determined using [35S]methionine-labeled IFN alpha-4a, in competition with unlabeled IFN alpha-2b, IFN alpha-4a, and IFN-beta. RESULTS: The melanoma cell lines differed markedly in their sensitivity to the IFNs tested: Five were sensitive to low concentrations (less than 30 pM) of IFN-beta, only one was sensitive to similar concentrations of IFN alpha-2b, and none were sensitive to IFN alpha-4a at concentrations up to 920 pM. For all cell lines, the antiproliferative potency of the type I IFNs was IFN-beta greater than IFN alpha-2b greater than IFN alpha-4a. IFN-gamma was less active than IFN-beta on all except one of the cell lines. Similarly, IFN-beta was more potent than IFN alpha-2a in inhibiting the growth of the LiBr xenograft in nude mice. Labeled IFN alpha-4a bound with high specificity in all four melanoma lines tested, and competitive binding experiments showed that the order of binding affinity (IFN-beta greater than IFN alpha-2b greater than IFN alpha-4a) correlated with the order of antiproliferative potency. CONCLUSION: The finding that melanoma cell lines differ intrinsically in their sensitivity to IFNs may explain differences in clinical response. Our results suggest that IFN-beta may be the most effective IFN in the treatment of melanoma, although confirmation will require clinical trials involving large numbers of patients.

Animals↗
PubMed1992

Epitope specificity of antibodies to type II collagen in rheumatoid arthritis and systemic lupus erythematosus.

Antibodies to human type II collagen were examined in the sera of 105 patients with rheumatoid arthritis (RA), 44 patients with systemic lupus erythematosus (SLE) and 11 patients who fulfilled the criteria of both diseases (RA-SLE overlap), using a solid-phase radioimmunoassay (RIA). The frequencies of antibodies to native and denatured human type II collagen were 20% and 27% in RA, 14% and 16% in SLE, and 45% and 36% in RA-SLE overlap. The specificity of the antibodies was further examined by inhibition with native and denatured type II collagen, by immunoblotting on native and denatured type II collagen, and by immunoblotting on cyanogen-bromide derived polypeptides of type II collagen. We could not identify any disease-specific patterns of reactivity. Thus, in the three disease groups the antibody response was polyclonal; there were antibody populations that reacted with native and/or denatured collagen, and epitopes could be assigned to at least three CB peptides, CB10.5, CB11 and CB8.

Antibodies↗
PubMed1992

Antibodies to glutamic acid decarboxylase are associated with HLA-DR genotypes in both Australians and Asians with type 1 (insulin-dependent) diabetes mellitus.

Antibodies to glutamic acid decarboxylase, previously known as the 64 kD antigen, appear to be more predictive of Type 1 (insulin-dependent) diabetes mellitus in Caucasoids than other autoantibodies to islet cell antigens. However, seropositivity to glutamic acid decarboxylase is not universal at the onset of Type 1 diabetes and the prevalence in Asians is low compared to Caucasoid patients. This suggests the involvement of multiple pancreatic autoantigens in the Type 1 diabetes autoimmune process or, genetic differences within and between ethnic groups that contribute to the heterogeneous autoimmune response to glutamic acid decarboxylase or both. Alternatively some cases of Type 1 diabetes could have an aetiology unrelated to autoimmunity. This study examined the differential response to glutamic acid decarboxylase according to HLA-DR and -DQ genotypes, as determined by RFLP, in 49 white Australian and 44 Asian patients with Type 1 diabetes. Among Australians heterozygous for HLA-DR3, DR4, 85% were positive for antibodies to glutamic acid decarboxylase, significantly different (p = 0.039) from the prevalence of 48% in patients with at least one HLA-DR antigen other than DR3 or DR4. Also, among Australians, the presence of "low risk" HLA-DQ antigens, namely DQw5, DQw6 or DQw7, reduced the prevalence of antibodies to glutamic acid decarboxylase by 40% (p = 0.064). Among Asians with Type 1 diabetes and with antibodies to glutamic acid decarboxylase, HLA-DR9 was significantly (p = 0.037) increased in frequency, at 63% compared with 22% in those without glutamic acid decarboxylase antibodies, and the presence of a "low risk" HLA-DQ allele reduced the antibody rates by 87% (p = 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Differing epitope selection of experimentally-induced and natural antibodies to a disease-specific autoantigen, the E2 subunit of pyruvate dehydrogenase complex (PDC-E2).

Naturally-occurring autoantibodies to a family of mitochondrial enzymes, the 2-oxoacid dehydrogenase complexes (2-OADC), characterize the human liver disease primary biliary cirrhosis. The immunodominant epitope for these autoantibodies is associated with the lipoyl-binding domain of the E2 subunit of the enzymes. The reactivity of these disease-associated autoantibodies was compared with that of antibodies raised in rats and rabbits, by immunization with various preparations derived from the 2-OADC enzymes, using immunization protocols that have successfully induced various organ-specific autoimmune diseases in animals. The immunogens included the intact pyruvate dehydrogenase complex (PDC) from bovine heart, human recombinant PDC-E2, and short synthetic peptides representing the immunodominant lipoic acid binding sequences of the 2-OADC enzymes. The techniques for antibody analysis included immunofluorescence, immunoblotting on mitochondrial extracts, ELISAs using entire PDC, PDC-E2, or synthetic peptides, epitope mapping by peptide scanning on overlapping octameric peptides representing the human PDC-E2 sequence, affinity purification on PDC-E2, and inhibition in vitro by sera of the catalytic function of PDC. Experimental immunization did not elicit any evidence of autoimmune disease. Moreover, the experimentally-induced antibodies in striking contrast to the natural autoantibodies showed preferential reactivity with PDC-E2 rather than with intact PDC, failed to inhibit in vitro the catalytic function of PDC, and, on peptide scanning, reacted with discrete epitopes, but at sites other than the lipoyl-binding region of PDC-E2. Our data indicate that 'multisystem' autoimmune diseases including primary biliary cirrhosis may not be elicitable experimentally because a critical disease-relevant autoepitope is not engaged by the immune system.

Amino Acid Sequence↗