Volume 37, Issue 3

The dysregulation of CTLA-4 (CD152), a glycoprotein expressed on the surface of lymphocytes, may lead to chronic inflammation. Based on the recent scientific findings, it has become clear that CTLA-4 inhibits the effector function and, thus, shuts down the effector phase of the T-lymphocytes. Interestingly, the CTLA-4-expressing cells become resistant to apoptosis (programmed cell death) and increasingly migrate to the lymph nodes and tissues. Studies have shown that regulatory T cells (Tregs), which switch off unwanted immune responses can inhibit in vivo only if they express an intact CTLA-4 gene. Moreover, it was confirmed that CTLA-4 is not only expressed on the T-lymphocytes but also on the B-lymphocytes. The mice with genetic inactivation of CTLA-4 in the B-lymphocytes show an increased production of the IgM antibodies after immunization. Interestingly, in particular, the B- and T-lymphocytes from the newborns and infants show a strongly increased CTLA-4 expression, suggesting a key immunoregulatory role in the neonatal immune responses. The molecules such as CTLA-4, which regulate the differentiation of the lymphocytes, could provide therapeutic targets during the early childhood to set the course for protection against autoimmunity and allergy.

The dysregulation of CTLA-4 (CD152), a glycoprotein expressed on the surface of lymphocytes, may lead to chronic inflammation. Based on the recent scientific findings, it has become clear that CTLA-4 inhibits the effector function and, thus, shuts down the effector phase of T-lymphocytes. Interestingly, the CTLA-4-expressing cells become resistant to apoptosis (programmed cell death) and increasingly migrate to the lymph nodes and tissues. Studies have shown that regulatory T cells (Tregs), which switch off unwanted immune responses can inhibit in vivo only if they express an intact CTLA-4 gene. Moreover, it was confirmed that CTLA-4 is not only expressed on T-lymphocytes but also on B-lymphocytes. The mice with genetic inactivation of CTLA-4 show in B-lymphocytes an increased production of IgM antibodies after immunization. Interestingly, in particular, B- and T-lymphocytes from newborns and infants show a strongly increased CTLA-4 expression, suggesting a key immunoregulatory role in neonatal immune responses. Molecules such as CTLA-4, which regulate the differentiation of lymphocytes, could provide therapeutic targets during the early childhood to set the course for protection against autoimmunity and allergy.

Background: The influence of venous congestion on the laboratory values has been demonstrated. The mean percentage deviations seem physiologically questionable because the results depend mainly on the absolute values at the time point t 0 . For a better assessment of the influence of venous congestion time, the biological variability should be taken into account. Methods: The routine laboratory tests were determined in 92 volunteers after up to 6 min of venous congestion. All the values were normalised against the local reference intervals by the z-transformation. Results: All the measured variables except creatinine and sodium showed statistically significant changes under venous congestion, irrespective of whether the changes were expressed as the percentages or z-values. The proteins and protein-associated substances like calcium increased, whereas the soluble small molecules like potassium and glucose decreased. The largest increase was seen for bilirubin (+9%), while the increase in calcium was low. After normalisation, however, the magnitude and the ranking of the congestion-dependent differences changed markedly. The highest increase could be shown for the total protein (+1.4 standard deviations), while bilirubin only revealed a slight increase. As expected, the changes for calcium became much more pronounced, corresponding with those of albumin. Conclusions: The normalised deviations meet the physiological expectations far better.

Background: The anti-cardiolipin and β 2 -glycoprotein I antibodies represent the important diagnostic parameters in routine autoimmune screening and represent the important diagnostic criteria for systemic lupus erythematosus (SLE). In this study, five different automated, semiautomated, and manual immunoassays detecting IgG/IgM anti-cardiolipin and anti-β 2 -glycoprotein I antibodies were tested. Methods: A total of 43 samples from the patients with SLE diagnosed in the rheumatology outpatient centers in Germany were included in this study. Results : For anticardiolipin and anti-β 2 -glycoprotein I, considerable differences in the percentage of the positive results were found between all the five methods, and the itemization of all the positive test results reached only a poor accordance. These findings were confirmed by Cohen’s κ coefficients. Conclusions: We found a moderate to poor accordance between the five different modern test systems for anticardiolipin and anti-β 2 -glycoprotein I antibodies. Such discrepancies can result in the clinical misinterpretation of data and may lead to wrong diagnoses. Therefore, further standardization of the tests for the antiphospholipid antibodies (APAs) is required. Zusammenfassung Hintergrund: Anti-Cardiolipin und β 2 -Glykoprotein I Antikörper präsentieren wichtige Parameter in der Routinediagnostik von Autoimmunerkrankungen und stellen ein wesentliches diagnostisches Kriterium für die Diagnose eines systemischen Lupus erythematodes (SLE) dar. In dieser Studie wurden erstmals alle gängigen modernen voll- und teilautomatisierten Analysesysteme hinsichtlich der Bestimmung von anti-Cardiolipin und β 2 -Glykoprotein I-Antikörpern miteinander verglichen. Methoden: Es wurden 43 Proben von Patienten mit diagnostiziertem systemischen Lupus erythematodes untersucht. Ergebnisse: Sowohl bei der Bestimmung von anti-Cardiolipin als auch von β 2 -Glykoprotein I-Antikörpern zeigten sich signifikante Unterschiede zwischen den verschiedenen Verfahren. Statistisch konnte dies durch Einzelbetrachtung der Ergebnisse mittels des Cohens Kappa-Koeffizienten verdeutlicht werden. Schlussfolgerung: Unsere Ergebnisse zeigen eine schwache bis fehlende Übereinstimmung der analytischen Resultate bei der Bestimmung von anti-Cardiolipin und von β 2 -Glykoprotein I-Antikörpern zwischen den aktuellen teil-/ vollautomatisierten Analyzern. Wesentlich für diese Beurteilung war dabei die Betrachtung der Einzelergebnisse und nicht die der gemittelten Gesamtheit. Abweichungen dieses Ausmaßes können in einer klinischen Fehldiagnose und fehlerhaften Therapie resultieren. Eine weitere Standardisierung ist erforderlich.

A well-accepted tool for method validation is a method comparison study. Results are usually assessed on a scatter plot of which the fitting line is calculated by several approaches, for example, ordinary (vertical) linear regression (OLR), orthogonal regression (OR), Deming regression (DR), Passing-Bablok method (PBR) or standardized principal component regression (SPCR). DR was applied in its general form (gDR), requiring information of the imprecision of at least two different quantities and as simple DR (sDR) with imprecision information of only one quantity. The equation of the regression line calculated by these concepts varies depending on range of measurement, analytical variation and on imprecision ratio ( s AY / s AX ). There is still a global debate about which statistical concept is the most adequate for validating purposes. Various paired random samples with a size of 100 were simulated in 5000 replicates and evaluated with different regression models. The behavior of the slope and intercept of the regression lines were compared under various conditions. Two extreme ranges of measurement and several variance ratios in the absence and presence of bias were studied. The results clearly demonstrated that DR is the only model which can be applied without any precautions under conditions which usually occur in method comparison studies, and therefore should be preferred in laboratory medicine. Other models require restrictions with regard to range of measurement and/or imprecision profile. Differences of the concentrations at different positions of the measurement interval calculated with regression coefficients of both DRs did not deviate more than the permissible bias. Therefore, the advantage of using gDR does not justify its greater disadvantages in comparison with sDR. Zusammenfassung Eine Methodenvergleichsstudie ist ein allgemein akzeptiertes Hilfsmittel der Methodenvalidierung. Die Ergebnisse werden oft auf einem Streudiagramm dargestellt, dessen Ausgleichsgerade mittels verschiedener Verfahren berechnet wird, wie z.B. (vertikale) lineare Regression (OLR), orthogonale Regression (OR), Deming Regression (DR), Passing-Bablok Methode (PBR) oder standardisierte Hauptkomponenten-Regression (SPCR). Die DR wurde in ihrer generalisierten Form (gDR), die Information der Impräzision wenigstens zweier unterschiedlicher Quantitäten, oder als einfache DR (sDR), die Impräzision nur einer Quantität benötigt, angewendet. Die mit diesen Konzepten berechneten Regressionslinien variieren in Anhängigkeit des Messbereichs, der analytischen Streuung und des Impräzionsverhäetnisses ( s AY / s AX ). Es findet immer noch eine globale Debatte über das für Validierungszwecke adäquate statistische Verfahren statt. 100 verschiedene gepaarte Zufallsproben wurden 5000 Mal einer Simulation mit den genannten Regressionsverfahren unterworfen. Das Verhalten von Steigung und Interzept der Regressionsgeraden wurde unter verschiedenen Bedingungen verglichen. Zwei extreme Messbereiche und verschiedene Varianzverhältnisse wurden in Ab- und Anwesenheit eines Bias untersucht. Die Ergebnisse zeigten eindeutig, dass nur die DR ohne Einschränkungen unter Bedingungen, die üblicherweise bei Methodenvergleichen vorkommen, angewendet werden können und daher in der Laboratoriumsmedizin vorzuziehen ist. Die anderen Modelle erfordern Restriktionen in Bezug auf den Messbereich und/oder die Impräzisionsprofile. Konzentrationsunterschiede an verschiedenen Positionen des Messbereichs, die mit den Regressionskoeffizienten beider DR berechnet wurden, wichen nicht mehr als der zulässige Bias von einander ab. Daher rechtfertigt der geringe Vorteil der gDR gegenüber der einfachen DR nicht deren erhöhten Aufwand.