Heterophile anti-mouse immunoglobulin antibodies may interfere with cytokine measurements in patients with HLA alleles protective for type 1A diabetes

Interfering with interferons: targeting the JAK-STAT pathway in complications of systemic juvenile idiopathic arthritis (SJIA)

Systemic JIA (SJIA) is distinguished from other forms of JIA by the prevalence of the severe, life-threatening complications macrophage activation syndrome (SJIA-MAS) and lung disease (SJIA-LD). Alternative therapeutics are urgently needed, as disease pathogenesis diverges from what is observed in SJIA, and currently available biologics are insufficient. SJIA-MAS, defined by a cytokine storm and dysregulated proliferation of T-lymphocytes, and SJIA-LD which presents with lymphocytic interstitial inflammation and pulmonary alveolar proteinosis, are both thought to be driven by IFNs, in particular the type II IFN-γ. Involvement of IFNs and a possible crosstalk of type I IFNs with existing biologics indicate a distinct role for the JAK-STAT signalling pathway in the pathogenesis of SJIA-MAS and SJIA-LD. Here, we review this role of JAK-STATs and IFNs in SJIA complications and discuss how new insights of ongoing research are shaping future therapeutic advances in the form of JAK inhibitors and antibodies targeting IFNs.

The role of endogenous IFN-β in the regulation of Th17 responses in patients with relapsing-remitting multiple sclerosis

IFN-β has been used as a first-line therapy for relapsing-remitting multiple sclerosis (RRMS). Because only a few studies have addressed the role of endogenous IFN-β in the pathogenesis of the disease, our objective was to characterize its role in the transcriptional regulation of pathogenic Th17 cytokines in patients with RRMS. In vitro studies have demonstrated that IFN-β inhibits IL-17A, IL-17F, IL-21, IL-22, and IFN-γ secretion in CD4(+) lymphocytes through the induction of suppressor of cytokine secretion 1 and suppressor of cytokine secretion 3. We found that patients with RRMS have increased serum and cerebrospinal fluid Th17 (IL-17A and IL-17F) cytokine levels in comparison with the control subjects, suggesting that deficient endogenous IFN-β secretion or signaling can contribute to the dysregulation of those pathogenic cytokines in CD4(+) cells. We identified that the endogenous IFN-β from serum of RRMS patients induced a significantly lower IFN-inducible gene expression in comparison with healthy controls. In addition, in vitro studies have revealed deficient endogenous and exogenous IFN-β signaling in the CD4(+) cells derived from patients with MS. Interestingly, upon inhibition of the endogenous IFN-β signaling by silencing IFN regulatory factor (IRF) 7 gene expression, the resting CD4(+) T cells secreted significantly higher level of IL-17A, IL-17F, IL-21, IL-22, and IL-9, suggesting that endogenous IFN-β suppresses the secretion of these pathogenic cytokines. In vivo recombinant IFN-β-1a treatment induced IFNAR1 and its downstream signaling molecules' gene expression, suggesting that treatment reconstitutes a deficient endogenous IFN-β regulation of the CD4(+) T cells' pathogenic cytokine production in patients with MS.

The biology of NKT cells

Recognized more than a decade ago, NKT cells differentiate from mainstream thymic precursors through instructive signals emanating during TCR engagement by CD1d-expressing cortical thymocytes. Their semi-invariant alphabeta TCRs recognize isoglobotrihexosylceramide, a mammalian glycosphingolipid, as well as microbial alpha-glycuronylceramides found in the cell wall of Gram-negative, lipopolysaccharide-negative bacteria. This dual recognition of self and microbial ligands underlies innate-like antimicrobial functions mediated by CD40L induction and massive Th1 and Th2 cytokine and chemokine release. Through reciprocal activation of NKT cells and dendritic cells, synthetic NKT ligands constitute promising new vaccine adjuvants. NKT cells also regulate a range of immunopathological conditions, but the mechanisms and the ligands involved remain unknown. NKT cell biology has emerged as a new field of research at the frontier between innate and adaptive immunity, providing a powerful model to study fundamental aspects of the cell and structural biology of glycolipid trafficking, processing, and recognition.

Interference in microsphere flow cytometric multiplexed immunoassays for human cytokine estimation

The present study describes positive and negative interference of human cytokine measurement in multiplexed bead-based immunoassays. Significant differences in measured IL-6 and TNF-alpha values in 30 normal human plasma samples were apparent depending on whether measurements were with a 2-plex assay or embedded in a multiplex of 8-or more cytokine antibody pairs, as well as among the kits of 3-different vendors. Sample diluents containing proprietary blocking ingredients were shown to greatly affect the outcome of measured cytokine values. Additionally, recovery of IL-6 and TNF-alpha from spiked samples suggests significant negative interference from either endogenous antibodies, soluble receptors or anti-cytokine antibodies in 10% and 26% of samples, respectively. While it is evident that multiplexed immunoassays hold great promise for cytokine profiling, there are still important issues needing further study. Especially needed are universally optimized sample diluents, uniformly calibrated standards with mass values, and internal assay controls, which should greatly facilitate intralaboratory accuracy and precision and interlaboratory comparisons of cytokine measurements. Possible causes of interference and remedies are discussed.

Frequent false positive beta human chorionic gonadotropin tests in immunoglobulin A deficiency

A patient with IgA deficiency had a series of positive serum pregnancy tests which led to medical and surgical procedures for suspected molar pregnancy. These tests were found to be falsely positive due to heterophile antibody. The aim of this study was to determine the frequency of false positive betahCG assays in sera of IgA deficient patients. Sera from a panel of IgA deficient (IgA < 7 mg/dl) patients were tested for the presence of betaHCG using three different assays, and also for IgG anti-goat and anti-mouse antibodies. Patients were seen at Mount Sinai Medical Center and included 54 patients (ages 1-80 years, 32 females, 22 males) with IgA deficiency. Thirty percent of 54 IgA deficient patient sera yielded positive pregnancy tests by one or more of the three betahCG assays, however, none of the patients were pregnant. In comparison to sera of normal controls, 39% of the patient sera contained significant amounts of anti-goat antibody and 18% contained significant amounts of anti-mouse antibody. While heterophile antibodies are common in IgA deficient serum, false positive assays for betahCG in IgA deficient serum have not been previously reported. The possibility of false positive test results should be considered prior to invasive procedures in IgA deficient patients.

The relationship among serum cytokines, chemokine, nitric oxide, and leptin in children with type 1 diabetes mellitus

OBJECTIVES

The aim of this study was to investigate the relationship between cytokines, leptin and vascular tone-related chemokine and nitric oxide (NO) in type 1 diabetic children.

DESIGN AND METHODS

Serum samples were collected from 58 children with type 1 diabetes and 33 of their healthy siblings.

RESULTS

Serum interleukin (IL)-8 was significantly higher and serum nitric oxide was significantly lower in the children with diabetes than in their healthy siblings. Stepwise regression analysis showed that there were significantly positive correlations between IL-1beta and IL-6, IL-1beta and nitric oxide, IL-4 and tumor-necrosis factor (TNF)-alpha, IL-4 and leptin, IL-8 and IL-2, and interferon (IFN)-gamma and IL-6, as well as significantly inversed correlations between IL-6 and IL-2, IL-8 and interferon-gamma, and leptin and TNF-alpha in siblings, not in the children with diabetes. However, there were significantly positive correlations between IL-2 and IL-4, IL-2 and leptin, IL-4 and IL-6, and TNF-alpha and IL-6 in children with diabetes.

CONCLUSIONS

Our results suggest that the alterations of circulating IL-8 and nitric oxide levels and cytokine network in children with diabetes may be associated with the cardiovascular disease in their adulthood.

Cytokine detection by ELISPOT: relevance for immunological studies in type 1 diabetes

Diabetes mellitus type 1 is a chronic disease in which the insulin-secreting ss-cells are selectively destroyed by an immune-mediated process. Autoantibodies directed against several islet antigens are useful parameters to estimate the risk to develop diabetes, but cell-mediated immunity involving T lymphocytes plays a major part in causing the specific destruction of ss-cells. T cells are characterized by their antigen-specificity, phenotype and cytokine-secreting profile. T cells that secrete cytokines of the T helper 1 (Th1) type have been shown to transfer diabetes in animal studies, in contrast to T helper 2 (Th2) cytokine-secreting T cells that are thought to be rather nondestructive. In the absence of phenotypic markers for Th1 and Th2 cells, several different approaches have been taken to examine T cell responses in detail. Methods involve T-cell proliferation assays, Enzyme-Linked-Immuno-Sorbent-Assay (ELISA) analysis of secreted cytokines and phenotype analysis applying flow cytometry. A more recent development is ELISPOT analysis, which enables the investigator to determine the qualitative and quantitative antigen-specific immune response on a single-cell level with regard to cytokine secretion. This article aims to give an introduction to the advantages and limitations inherent in the different techniques and their potential relevance for immunological studies in diabetes mellitus type 1.

Heterophile antibodies indicate progression of autoimmunity in human type 1 diabetes mellitus before clinical onset

We previously reported serum cytokines in a group of long term non-progressors to Type 1 diabetes; this reactivity detected in ELISA is now identified as heterophile antibody in some sera. Here, we characterize heterophile antibody activity. A 14 kDa-polypeptide from heterophile antibody containing serum bound to an anti-IL-4 column, but IL-4 was not detected by Western blot or by MS/MS sequencing. However, in 2/13 heterophile antibody positive sera, T-cell growth was potentiated and was blocked by an anti-human immunoglobulin. To examine the relationship between low affinity heterophile antibody presence and disease progression, 1100 archived serum samples were analyzed with two pairs of antibodies from 443 diabetes-free first degree relatives of Type 1 diabetes mellitus patients for heterophile antibody; 95 individuals developed diabetes on follow-up. Twenty-two individuals, whose serum was heterophile antibody positive with the second pair of antibodies (but negative with the first pair of antibodies), had a significantly higher incidence of developing diabetes after five years. Thirty-seven individuals with heterophile antibody reactivity with the first pair of antibodies, regardless of reactivity with the second pair of antibodies, had a significantly lower incidence of developing diabetes. While we cannot exclude the presence of genuine cytokine in all sera, these data indicate the presence of distinct groups of heterophile antibodies in patients at high risk to develop diabetes. Thus, anti-Ig heterophilic antibodies with different immunochemical reactivities are linked to the progression of or protection from Type 1 diabetes autoimmunity.

Detection of GAD65-reactive T-Cells in type 1 diabetes by immunoglobulin-free ELISPOT assays

OBJECTIVE

To investigate the prevalence of beta-cell autoantigen-reactive peripheral T-cells in type 1 diabetes, we developed an immunoglobulin-free enzyme-linked immunospot (ELISPOT) assay and assessed its usefulness for diagnosing this disease.

RESEARCH DESIGN AND METHODS

Cellular immune responses to beta -cell autoantigens were studied both by immunoglobulin-free proliferation assays and ELISPOT assays in 33 patients with type 1 diabetes and 15 patients with type 2 diabetes, compared with 23 healthy control subjects. Autoantibodies against GAD65 and IA-2 were measured by radioimmunoassay.

RESULTS

Significant proliferative responses to GAD65 were observed in 10 of 31 (32.3%) type 1 diabetic patients (P < 0.05), whereas GAD65-reactive gamma-interferon (IFN-gamma)-secreting cells were detected in 22 of 33 patients (66.7%) by ELISPOT assay (P < 0.001). Of patients negative for both GAD65 and IA-2, five of six (83.3%) showed IFN-gamma positivity in ELISPOT and two of five (40.0%) showed significant proliferation against GAD65.

CONCLUSIONS

Using a newly developed ELISPOT assay, GAD-reactive T-helper 1 cells in PBMC of type 1 diabetic patients could be identified at a higher frequency than by the proliferation assay. Therefore, the immunoglobulin-free ELISPOT assay is an excellent tool for detecting T-cell reactivity to autoantigens with greater specificity and, in combination with beta-cell autoantibody determination, will improve the diagnosis of type 1 diabetes.

Serum IFN-gamma and IL-10 levels are associated with disease progression in non-obese diabetic mice

BACKGROUND

The goal of the present study was to determine whether cytokines in the peripheral blood of naive NOD mice correlate with the disease process and thereby would provide a marker for monitoring disease activity.

METHODS

Female NOD mice (5, 10 and 14-16 weeks of age) were investigated in a cross-sectional study. In the group of 14-16-week-old mice, non-diabetic and diabetic mice were analysed as different subgroups. The Th1 cytokine (IFN-gamma) and the Th2 cytokine (IL-10) were quantified in serum by sandwich enzyme-linked immunosorbent assay (ELISA). Pancreatic mRNA for IFN-gamma and IL-10 was determined by reverse transcriptase-polymerase chain reaction (RT-PCR) from the same animals.

RESULTS

Serum levels of IFN-gamma were initially low but increased with age in NOD mice, reaching the highest levels at diabetes onset (p<0.002 compared to 10 weeks). A similar rise was noted in IFN-gamma gene expression in pancreatic lesions. In contrast, an early peak of serum IL-10 levels was observed in non-diabetic NOD mice (10 weeks) at a stage where non-destructive insulitis occurs. With increasing age a continuous loss of IL-10 until progression towards diabetes was observed. The pancreatic IL-10 mRNA expression correlated with serum IL-10 changes. As a consequence, the ratio of IFN-gamma/IL-10, reflecting the Th1/Th2 balance in the serum, was significantly increased in diabetic compared to non-diabetic NOD mice (p<0.005).

CONCLUSION

These results demonstrate, for the first time, that an increased Th2 pattern in the non-diabetic stage preceding a Th1 shift is associated with the development of diabetes in naive NOD mice. Serum cytokines correlate with disease progression and pancreatic cytokine expression during prediabetes. Soluble cytokines measured in the periphery are therefore promising surrogate markers of diabetes development.

Clinical application of NKT cell assays to the prediction of type 1 diabetes

Type 1 diabetes is a disease characterised by disturbed glucose homeostasis, which results from autoimmune destruction of the insulin-producing beta cells in the pancreas. The autoimmune attack, while not yet fully characterised, exhibits components of both mis-targeting and failed tolerance induction. The involvement of non-classical lymphocytes in the induction and maintenance of peripheral tolerance has recently been recognised and natural killer T (NKT) cells appear to play such a role. NKT cells are a subset of T cells that are distinct in being able to produce cytokines such as IL-4 and IFN-gamma extremely rapidly following activation. These lymphocytes also express some surface receptors, and the lytic activity, characteristic of NK cells. Deficiencies in NKT cells have been identified in animal models of type 1 diabetes, and a causal association has been demonstrated by adoptive transfer experiments in diabetes-prone NOD mice. Preliminary work suggests that a similar relationship may exist between deficiencies in NKT cells and type 1 diabetes in humans, although the techniques reported to date would be difficult to translate to clinical use. Here, we describe methods appropriate to the clinical assessment of NKT cells and discuss the steps required in the assessment and validation of NKT cell assays as a predictor of type 1 diabetes.

Multiplex analysis of heterophil antibodies in patients with indeterminate HIV immunoassay results

We hypothesized that heterophil antibodies reactive with animal proteins used in blot preparation caused nonspecific staining (NSS) on HIV Western blot (WB) studies, causing indeterminate results. We analyzed samples showing NSS on HIV WB using a multiplexed immunoassay to simultaneously measure IgG antibodies to animal IgG (bovine, goat, sheep, mouse) and bovine serum albumin. Heterophil antibodies reactive with IgG from several animal species were detected in 23 (49%) of 47 samples showing NSS on HIV WB; 15 positive samples demonstrated antibodies to all 5 antigens. Similar IgG heterophil antibodies were detected in only 2 (8%) of 24 control samples. Of the HIV WB samples with a positive HIV-1 enzyme-linked immunosorbent assay (ELISA) result at the time of WB testing (11/47), heterophil antibodies were found in 8 (73%) of 11. Preabsorption with bovine, goat, and sheep IgG removed heterophil antibodies detected by the multiplexed assay and, in some cases, eliminated reactivity in ELISA and WB testing. Heterophil antibodies are associated with indeterminate HIV immunoassay results and are an important cause of false-positive HIV ELISA results. Multiplexed immunoassays provide a powerful tool for screening patients for heterophil antibodies and resolving possible false-positive results.

Elevated serum IP-10 levels observed in type 1 diabetes

OBJECTIVE

Although most patients with type 1 diabetes are considered to have T-cell-mediated autoimmune disease, a method of measuring of pancreatic beta-cell-specific T-cell function in cases of type 1 diabetes has yet to be established. Here, we focused on interferon-inducible protein-10 (IP-10), a chemokine that promotes the migration of activated T-helper 1 (Th1) cells and measured serum IP-10 levels in patients with human type 1 diabetes, which is regarded as a Th1-mediated disease.

RESEARCH DESIGN AND METHODS

Serum samples were obtained from diabetic patients, and the levels of autoantibodies (GAD and insulinoma-associated protein-2 [IA-2]) and IP-10 were measured. Diabetic patients positive for either or both of the autoantibodies were classified as Ab+ type 1, and those negative for both were classified as Ab type 1. To evaluate islet antigen-specific responses, peripheral blood from patients stimulated with or without GAD was used, and intracellular cytokine staining for flowcytometry was performed.

RESULTS

The Ab+ and Ab- type 1 groups both showed a significantly higher serum IP-10 level than the healthy subjects (P < 0.001 and P < 0.05, respectively), and the IP-10 level in the recent-onset Ab+ subgroup was significantly higher than that in the established (longstanding) Ab+ subgroup (P < 0.002). Furthermore, there was a significant positive correlation between the serum IP-10 level and the number of GAD-reactive gamma-interferon-producing CD4+ cells in the Ab+ type 1 group (P < 0.007).

CONCLUSIONS

Our findings demonstrate that measurement of serum IP-10 concentrations is useful in patients with type 1 diabetes.

Heterophile antibodies segregate in families and are associated with protection from type 1 diabetes

Markedly elevated levels of serum IL-4 were reported previously in 50% of a small group of type 1 diabetes nonprogessors. To determine the patterns of expression for this phenotype, a larger cohort of 58 families containing type 1 diabetic patients was examined. Analysis of the two-site ELISA assay used to measure serum IL-4 revealed evidence for heterophile antibodies, i.e., nonanalyte substances in serum capable of binding antibodies mutivalently and providing erroneous analyte (e.g., IL-4) quantification. Interestingly, relatives without type 1 diabetes were significantly more likely to have this phenotype than were patients with the disease (P = 0.003). In addition, the trait appears to have clustered within certain families and was associated with the protective MHC allele DQB1*0602 (P = 0.008). These results suggest that heterophile antibodies represent an in vivo trait associated with self-tolerance and nonprogression to diabetes.