Evaluation of a novel point-of-care test for the rapid semi-quantitative detection of allergen-specific immunoglobulin E.

BACKGROUND: Allergen-specific IgE levels in human sera support the diagnosis of allergies. However, commonly used laboratory tests are time consuming. The new point-of-care test FastCheckPOC 20 (FCP20) allows the simultaneous and semi-quantitative evaluation of IgE antibodies for 20 aeroallergens and food allergens. METHODS: Two hundred patients with allergic symptoms were included in a multicenter performance evaluation using both whole blood and plasma or serum samples. FCP20 results were compared with the skin prick test (SPT) and the ImmunoCAP system (Phadia) which was used as reference for specific IgE values. RESULTS: The concordance between FCP20 and ImmunoCAP was 76% for positive results and 80% for negative results over 20 allergens. Overall agreement (accuracy) of FCP20 with the ImmunoCAP was 80% across all 20 allergens. The concordance between FCP20 and SPT over all 20 allergens was 66% for positive results and 71% for negative results. Overall agreement of FCP20 with the SPT was 70%. Semi-quantitative FCP20 results (Levels 1-5) revealed nearly identical values for whole blood and plasma/serum test results. A good concordance was also observed between FCP20 levels and ImmunoCAP classes. CONCLUSIONS: FastCheckPOC 20 is reliable to determine allergen-specific IgE in human whole blood and plasma/serum samples.

Interleukin-7 levels in synovial fluid increase with age and MMP-1 levels decrease with progression of osteoarthritis.

BACKGROUND AND PURPOSE: Little is known about biochemical mediators that correlate with the initiation and progression of knee osteoarthritis (OA). We therefore valuated the roles of cytokines and metalloenzymes in knee OA in relation to OA grading, age, and BMI. PATIENTS AND METHODS: A multiplex ELISA-based immunoassay (Luminex technology) was used to measure biochemical mediators in the synovial fluid (SF) of 82 patients undergoing knee surgery. All patients were classified according to age, BMI, and OA grade. 24 patients had no signs of OA (knee reconstruction surgeries). The mediators that were tested for included interleukins (IL-1Ra, IL-6, IL-7, and IL-18), chemokines (CCL2 (MCP-1), CCL3 (MIP-1a), and CXCL8 (IL-8)), growth factors (HGF and VEGF), and matrix metalloproteinases (MMP-1, MMP-2, MMP-9, and MMP-13). RESULTS: There was a correlation between IL-7 levels in SF and age (p < 0.01). The 11 highest IL-7 levels were seen in patients who were aged between 59 and 72 but had different OA grades. In contrast, all patients who had severe OA in all 3 knee compartments (pan-OA) had only low or medium IL-7 levels. There was a negative correlation between MMP-1 levels in synovial fluid and grade of OA (p < 0.001). Correlation studies between pairs of mediators revealed two groups of mediators that are important in OA progression, dominated by MCP-1 and IL-1Ra. INTERPRETATION: IL-7 levels in SF are elevated in elderly people suffering from OA of different grades, but they are depressed in patients with severe 3-compartment OA, possibly due to widely impaired chondrocytes embedded in the affected cartilage tissue. The observed decrease in MMP-1 levels in SF, which is dependent on the severity of OA, may be caused by deterioration of superficial cartilage layers during progression of OA.

The C-terminal domain of the betaine carrier BetP of Corynebacterium glutamicum is directly involved in sensing K+ as an osmotic stimulus.

The glycine betaine carrier BetP of Corynebacterium glutamicum was recently shown to function both as an osmosensor and as an osmoregulator in proteoliposomes by sensing changes in the internal K(+) concentration as a measure of hyperosmotic stress. In vivo analysis of mutants carrying deletions at the C-terminal extension of BetP indicated that this domain participates in osmostress-dependent activity regulation. To address the question, whether a putative K(+) sensor is located within the C-terminal domain, several mutants with truncations in this domain were purified and reconstituted in proteoliposomes of Escherichia coli phospholipids, since this in vitro system allowed variation of the K(+) concentration at the lumenal side. Truncation of 12 amino acids led to a partly deregulated BetP in terms of osmoregulation; however, K(+) sensitivity was not impaired in this mutant. The deletion of 25 amino acid residues at the C-terminal end of BetP led to both deregulation of the carrier activity, i.e., high activity independent of external osmolality, and loss of K(+)-dependent transport stimulation, indicating that this region of the C-terminal domain is necessary for K(+) sensing and/or K(+)-dependent carrier activation. Immunological and proteolysis analyses showed that BetP and its recombinant forms were reconstituted in a right-side-out orientation, i.e., the C-terminal domain faces the lumen of the proteoliposomes and is thus able to detect the K(+) signal at the inside. This is the first experimental demonstration of a direct connection between an osmotic stimulus, i.e., the change in internal K(+), and a putative sensor domain.