Qualitative and quantitative comparison of allergen component-specific to birch and grass analyzed by ImmunoCAP assay and Euroline immunoblot test

Summary

Background.In the diagnostic work up of allergy, determining allergen component-specific immunoglobulin E (IgE) is important for diagnosis, prognosis and choice of treatment. The purpose of this study was to evaluate the performance of the immunoblotting assay (Euroline) in detection of IgE antibodies against timothy grass and birch pollen allergen components compared to fluorescent enzyme assay (ImmunoCAP, Phadia 250). Methods. A total of 128 serum samples from patients allergic to timothy grass and birch pollen were analysed. The levels of IgE antibodies to timothy grass and birch pollen were measured using Euroline DPA-Dx pollen 1 and ImmunoCAP assay. The two methods were then compared on binary (positive vs negative), semi-quantitative (IgE classes) and quantitative (concentration) levels. The two methods were also compared to results from skin prick testing. Results. The Euroline method showed a positive percentage agreement of 93% and negative percentage agreement of 94% with an overall accuracy of 94% when compared to ImmunoCAP. Kappa analysis showed moderate strength of agreement between the methods in determining IgE classes for 7/11 components tested. All components showed a positive correlation when analysed using Spearman's rank correlation. Conclusions. Overall, we found that there is good correlation between the Euroline and ImmunoCAP methods in measuring IgE sensitization.

Pre-treatment allergen-specific IgE analysis and outcomes of allergen immunotherapy

Summary

Background. Patients show varied results to allergen immunotherapy (AIT. The reason for this variability is unclear. Objective. To describe the relationship between AIT efficacy and demographic characteristics, as well as pre-treatment plasma levels of specific IgE-antibodies to grass and birch pollen. Methods. A retrospective study was performed based on medical records of 128 patients who received AIT. The patients completed a questionnaire and pre-AIT plasma levels of allergen-specific IgE to grass and birch pollen were measured using EUROLINE DPA-Dx pollen 1 method. Results. Seventy percent of patients classified their allergic symptoms as less severe after AIT. Twenty-seven percent had received AIT targeting only grass pollen, 19% targeting only birch pollen, and 55% targeting both grass and birch. A total of 35 different IgE profiles were found across our study population. On comparison of the demographic characteristics and concentration of allergen-specific IgE-antibodies, no statistically significant differences could be found.Conclusions. The majority of patients rated their allergic symptoms as less severe after AIT. No clear relationship could be demonstrated between pre-treatment allergen-specific IgE concentration, or demographic characteristics, and effect of AIT. There may be other factors underlying the different responses to AIT.

Chironomid midge sensitization in sewage workers: case study

Non-biting chironomid midges (Diptera: Chironomidae) may cause sensitization and allergic reactions in humans and have recently been identified as a potential health problem in Swedish municipal sewage treatment plants. To investigate, on a pilot scale, the allergenic potential of chironomids in sewage workers, all workers (n = 8) at a sewage treatment plant and local controls (n = 16) completed a symptom questionnaire, underwent measurement of the fraction of nitric oxide in exhaled air, spirometry, and provided serum samples for the determination of atopy status and the prevalence of specific immunoglobulin E (IgE) antibodies against Chironomus thummi (Chi t) using a commercial fluorescence enzyme immunoassay (FEIA). Three sewage workers (38%) but no controls (0%) were FEIA positive for C. thummi-specific IgE antibodies (P < 0.05). No other health-related findings were significantly different between the groups. The study suggested that occupational exposure to Chironomids may cause sensitization with circulating IgE-antibodies in sewage workers.

Is interleukin-18 useful for monitoring rheumatoid arthritis?

OBJECTIVE

Interleukin-18 (IL-18) is a proinflammatory regulator of immune responses. Its similarities to IL-1beta and ability to induce tumour necrosis factor-alpha (TNF-alpha) make it potentially important in the pathogenesis of rheumatoid arthritis (RA).

METHODS

The level of IL-18 was assessed in matched pairs of blood and synovial fluid samples from 90 RA patients (47 erosive, 43 non-erosive) by an enzyme-linked immunosorbent assay (ELISA), and the results compared to 40 healthy controls.

RESULTS

In RA patients with erosive joint disease, the IL-18 level was higher than that in non-erosive RA [(median+/-QR) blood: 385+/-200 vs. 235+/-183 pg/mL, p = 0.02; synovial fluid: 392+/-392 vs. 224+/-324 pg/mL, p = 0.05]. IL-18 levels in blood of RA patients were similar and closely related to the local, intra-articular level (r = 0.96). The IL-18 level was not related to other markers of inflammation, to the duration of RA, or to the treatment modality. The IL-18 level in RA patients was similar to that of the controls (278+/-234 vs. 344+/-179 pg/mL, not significant).

CONCLUSIONS

An increased IL-18 level is associated with erosive joint disease, but the measurement of IL-18 does not help to distinguish between RA patients and healthy controls.

Leptin consumption in the inflamed joints of patients with rheumatoid arthritis

BACKGROUND

Leptin has been shown to participate in bone remodelling and leptin substitution reported to have a protective effect in experimental septic arthritis.

OBJECTIVE

To assess leptin levels in inflamed joints and plasma of patients with RA.

MATERIAL AND METHODS

Leptin concentrations were assessed in matched blood and synovial fluid samples from 76 patients with RA. Blood samples from 34 healthy subjects acted as additional controls. Results were analysed and correlated with duration and activity of RA, x ray changes, and treatment at time of sampling.

RESULTS

In patients with RA, leptin levels were significantly higher in plasma than in synovial fluid samples obtained simultaneously and higher than in control samples. Plasma and synovial fluid leptin levels correlated strongly. Locally in the joint, leptin levels were related to WBC count. Such a relation was not seen in the bloodstream. Leptin levels were not related to sex, age, or disease duration. Difference between leptin levels in plasma and synovial fluid was greater in non-erosive arthritis (5.1 (SEM 1.2) v 3.7 (0.9) ng/ml, p=0.006), than in patients with erosive joint disease (6.2 (1.0) v 5.4 (0.8) ng/ml, NS). Methotrexate treatment was associated with relatively high plasma leptin levels, while treatment with other DMARDs was associated with lower leptin levels than in patients receiving no DMARD treatment (p=0.0005).

CONCLUSIONS

Leptin production was significantly increased in patients with RA compared with healthy controls. Synovial fluid leptin levels were significantly lower than in matched plasma samples, suggesting an in situ consumption of this molecule.

Outcome of Staphylococcus aureus-triggered sepsis and arthritis in IL-4-deficient mice depends on the genetic background of the host

Disruption of the IL-4 gene in two inbred mouse strains revealed a dual role of IL-4 in Staphylococcus aureus sepsis and arthritis depending on the host's genetic background. IL-4 was protective in 129SV mice, since 5 days after S. aureus inoculation IL-4(-/-) mice displayed 70% mortality as compared to survival of all 129SV wild-type counterparts. On the other hand, IL-4 was detrimental in C57BL/6 mice, since survival of IL-4(-/-) C57BL/6 mice was increased, as compared to wild-type controls, due to decreased staphylococcal growth. Altogether, our results show the dual role of IL-4 in S. aureus sepsis and arthritis, depending on the genetic background of the host.

TNF/lymphotoxin-alpha double-mutant mice resist septic arthritis but display increased mortality in response to Staphylococcus aureus

To evaluate the importance of the proinflammatory cytokines TNF and lymphotoxin-alpha (LT alpha) in an experimental model of Staphylococcus aureus sepsis and arthritis, we used TNF/LT alpha-double-deficient mice raised on the C57BL/6 background. Mice were i.v. inoculated with a toxic shock syndrome toxin-1 (TSST-1)-producing S. aureus strain, LS-1. Intravenous inoculation of a high dose of bacteria (1 x 10(7)/mouse) resulted in 67% mortality in TNF/LT alpha-deficient mice, whereas none of the controls died (p = 0.009). Those results correlated to a significantly decreased phagocytosis in vitro and inefficient bacterial clearance in vivo in mice lacking capacity to produce TNF/LT alpha. Thus, at day 6 after inoculation, S. aureus could not be found in the bloodstream of controls, but bacteremia developed in all TNF/LT alpha-deficient mice examined (p = 0.02). Interestingly, upon infection with a lower dose of staphylococci (3 x 10(6)/mouse) the mortality was overall low, but the frequency of arthritis was clearly higher in the wild-type group as compared with the TNF/LT alpha-deficient mice (40% vs 13%). Histopathologic examination revealed a lower frequency of synovitis (38% vs 90%, p < 0.05) and erosivity (25% vs 60%, NS) in TNF/LT alpha-deficient mice as compared with wild-type counterparts. Our results show the importance of TNF/LT alpha in defense against systemic S. aureus infections and point out the detrimental role of these cytokines as mediators of inflammatory response in S. aureus arthritis.

Staphylococcus aureus-induced septic arthritis and septic death is decreased in IL-4-deficient mice: role of IL-4 as promoter for bacterial growth

Lack of IL-4 has been shown to be protective in some experimental models of infectious diseases in mice such as cutaneous leishmaniasis. At the same time IL-4, together with other Th2 cytokines, including IL-10 and IL-13, is known as an anti-inflammatory cytokine with the potential to down-regulate proinflammatory cytokine production. To investigate the role of IL-4 in experimental Staphylococcus aureus-induced and T lymphocyte-mediated arthritis, IL-4-deficient C57BL/6 mice (IL-4(-/-)) and their congenic controls (IL-4(+/+)) were inoculated with a toxic shock syndrome toxin-1-producing S. aureus strain. In IL-4(+/+) mice, arthritis peaked 14 days after bacterial inoculation, whereas, at that time, IL-4(-/-) mice displayed significantly less frequent (p < 0.05) joint inflammation. Paralleling lower frequency of arthritis, IL-4-deficient mice showed a decreased bacterial burden in joints (p = 0.014) and kidneys (p = 0.029), as well as lower infection-triggered weight decrease and mortality. In vitro, IL-4 inhibited intracellular killing of S. aureus in infected macrophages, without affecting phagocytosis. This finding may explain the enhanced staphylococcal clearance observed in IL-4(-/-) mice in vivo. Our results suggest that IL-4 and IL-4-dependent Th2 responses promote septic arthritis and sepsis-related mortality by inhibition of bacterial clearance during S. aureus infection.