Evaluation of a new ELISA for the detection of specific IgG to the Epstein-Barr nuclear antigen 1 (EBNA-1).

Diagnosis of acute primary Epstein-Barr Virus (EBV) infection is predominantly performed by serology. Detection of specific antibodies to defined EBV antigens is considered state of the art. Antibodies to EBNA-1 are not produced early in primary infection and a positive EBNA-1 serology is a sign of past infection. Therefore EBNA-1 serology plays a crucial role for EBV routine diagnosis. In the present study the quantitative EBV EBNA-1-IgG-ELISA PKS medac was evaluated regarding its suitability for routine diagnosis. Using clinically and diagnostically defined serum samples (141 from seronegative, 111 from acute infected, and 52 from individuals with past infection) as well as 100 sera from healthy blood donors the diagnostic performance of the assay was investigated. Furthermore, precision, performance of the single-point quantitation (SPQ), and suitability of the assay for automation were evaluated. Compared to the pre-definition of the serum panel a sensitivity of 100% and a specificity of 99.6% was found. The measurement of the blood donor sera resulted in an anti-EBNA-1 IgG prevalence of 93% and an agreement of 99% with the results of a commercial ELISA used as reference. Regarding intra-assay variation, interassay variation (performed manually and automatically), and person-to-person variation a coefficient of variation < 10% was found with reactive samples. A good dilution linearity (r2 = 0.961), an excellent correlation of SPQ vs. the calibration curve (r2 = 0.997), and between the results of manually vs. automatically performed test runs (r2 > 0.995) was found. The evaluation has shown that the assay meets the demands of routine diagnosis very well.

Platelet-derived chemokines CXC chemokine ligand (CXCL)7, connective tissue-activating peptide III, and CXCL4 differentially affect and cross-regulate neutrophil adhesion and transendothelial migration.

In this study, we have examined the major platelet-derived CXC chemokines connective tissue-activating peptide III (CTAP-III), its truncation product neutrophil-activating peptide 2 (CXC chemokine ligand 7 (CXCL7)), as well as the structurally related platelet factor 4 (CXCL4) for their impact on neutrophil adhesion to and transmigration through unstimulated vascular endothelium. Using monolayers of cultured HUVEC, we found all three chemokines to promote neutrophil adhesion, while only CXCL7 induced transmigration. Induction of cell adhesion following exposure to CTAP-III, a molecule to date described to lack neutrophil-stimulating capacity, depended on proteolytical conversion of the inactive chemokine into CXCL7 by neutrophils. This was evident from experiments in which inhibition of the CTAP-III-processing protease and simultaneous blockade of the CXCL7 high affinity receptor CXCR-2 led to complete abrogation of CTAP-III-mediated neutrophil adhesion. CXCL4 at substimulatory dosages modulated CTAP-III- as well as CXCL7-induced adhesion. Although cell adhesion following exposure to CTAP-III was drastically reduced, CXCL7-mediated adhesion underwent significant enhancement. Transendothelial migration of neutrophils in response to CXCL7 or IL-8 (CXCL8) was subject to modulation by CTAP-III, but not CXCL4, as seen by drastic desensitization of the migratory response of neutrophils pre-exposed to CTAP-III, which was paralleled by selective down-modulation of CXCR-2. Altogether our results demonstrate that there exist multiple interactions between platelet-derived chemokines in the regulation of neutrophil adhesion and transendothelial migration.