Zusammenfassung Die Aktualisierung der Richtlinie der Bundesärztekammer zur Qualitätssicherung laboratoriumsmedizinischer Untersuchungen (RiLiBÄK) macht es notwendig, für die CD4 und CD8 positiven Lymphozyten im peripheren Blut aktuelle Werte für die Präzision und Richtigkeit zu ermitteln. Dazu wurden bekannte Institutionen, welche diese Untersuchungen durchführen, direkt und indirekt über die Gerätehersteller bzw. Vertreiber um die Mitteilung im Rahmen ihrer Validierung und Qualitätskontrolle erhobenen Werte gebeten. Aus diesem soll eine Evidenz-basierte Grundlage für die Festlegung der Streumaße für die interne und externe Qualitätskontrolle gewonnen werden. Es existiert im Bereich der Immunphänotypisierung keine allgemein anerkannte Referenzmethode, so dass am Markt verschiedene Vorgehensweisen existieren. Im Ringversuch werden dementsprechend nach Methoden, Geräten und Reagenzien getrennte Gruppen gebildet mit einem Konsensuswert als Zielwert. Der Artikel beschreibt die Methoden-bedingten Unterschiede. Die Rückantworten geben eine Übersicht des gegenwärtigen Stands der Technik und eine deskriptive Beschreibung der methodeninhärenten Streuung. Dabei wurden auch die übrigen Lymphozytensubpopulationen berücksichtigt, um ein besseres Verständnis des Kontextes und des Methodenhintergrunds herbeizuführen. Abstract The review of the German guidelines for quality control of medical laboratory investigations made it necessary to determine the actual standard of imprecision and correctness of CD4 and CD8 lymphocyte subsets in peripheral blood. In this study, known laboratories performing that test were approached directly or indirectly via the manufacturers of reagents and equipment, in order to report the data they obtained by validation and internal quality control. In addition, the authors asked for reference ranges and results of the external quality assessments. Due to the fact that no reference methods exist, there are different procedures in the field and round-robin definition of subgroups with different target values obtained by consensus. This article describes the different procedures and technologies as well as the given spread of results. The report also covers the remaining lymphocyte subsets to gain a better understanding of the context and background of the technology.

The review of the German guidelines for quality control of medical laboratory investigations made it necessary to determine the actual standard of imprecision and correctness of CD4 and CD8 lymphocyte subsets in peripheral blood. In this study, known laboratories performing that test were approached directly or indirectly via the manufacturers of reagents and equipment, in order to report the data they obtained by validation and internal quality control. In addition, the authors asked for reference ranges and results of the external quality assessments. Due to the fact that no reference methods exist, there are different procedures in the field and round-robin definition of subgroups with different target values obtained by consensus. This article describes the different procedures and technologies as well as the given spread of results. The report also covers the remaining lymphocyte subsets to gain a better understanding of the context and background of the technology.

Zusammenfassung Das automatisiert gemessene Differentialblutbild stellt eine der häufigsten Untersuchungen im medizinischen Labor dar. Wie zuverlässig ist die Methode als diagnostisches Sieb im Rahmen einer Stufendiagnostik? Welche pathologischen Bilder werden übersehen? Welche Körperflüssigkeiten können untersucht werden? Was sind die präanalytischen Vorraussetzungen? Wann ist eine mikroskopische Kontrolle erforderlich? Die Kostenerstattung hat einen Punkt erreicht, wo eine persönliche Begutachtung eines jeden Ergebnisses mit seinen Diagrammdarstellungen und die mikroskopische Untersuchung des Blutausstrichs kaum mehr geleistet werden kann. Die Technologie der aktuellen Geräte am Markt ist kürzlich an dieser Stelle beschrieben worden. Nachfolgend werden daher die Stärken und Schwächen der automatisierten Blutbilderstellung diskutiert, um im Labor eine Entscheidungsgrundlage zu haben für die Risiken einer Stufendiagnostik in Abhängigkeit von der Fachrichtung des Einsenders.

Although the pathogenesis of HIV infection is independent of age, specific considerations have to be taken into account for the treatment of infants, children and adolescents. In addition to more cautious drug therapy, it is proposed to follow up disease progression by repeated measurement of CD4 lymphocyte percentage (CD4%). Unfortunately, this requires complicated, expensive analytical techniques and complex sample preparation protocols. This is one of the reasons why treatment of the increasing number of children suffering from HIV/AIDS in developing countries remains a challenge. We evaluated a new and simplified no lyse no wash protocol to measure CD4% on a volumetric flow cytometer. Eight blood samples of healthy and HIV-infected individuals were sent to five German hospital laboratories (centres B-F) and were measured by their flow cytometric in-house techniques. The results were compared to those of centre A using the volumetric technique with the new sample preparation protocol. Comparative data with established protocols and flow cytometric techniques showed good correlations for the determination of leukocytes and for lymphocytes. Comparing CD4% results of centre A (new protocol and volumetric measuring technique) with the highest and lowest values of centres B-F by Bland-Altman analysis yielded a bias of -1.02% (SD 3.16) and 4.27% (SD 3.72) over the whole range (4.01%-70.56%), respectively. A comparably simple three-step protocol as introduced for absolute CD4+ cell count can be used to calculate CD4% only by the addition of two antibodies (CD4 and CD45). The cost per test is in the range of (sic)2.50 and therefore far below current prices of (sic)5.00-(sic)40.00.

Abstract Complete blood count including automated blood cell differential is one of the most frequent tests in the medical laboratory. How reliable is the method representing a diagnostic sieve in a stepwise diagnostic approach? Which pathologic conditions will be overlooked? Which body fluids can be investigated? What are the preanalytical requirements? When is a microscopic review required? Reimbursement has reached a level where a personal review of the diagram of cell clusters and of the blood film cannot be afforded. As the technology of blood cell analyzers has recently been described in this journal, this article focuses on the strengths and weaknesses of the automated blood cell differential. This allows judgment of the risks of a stepwise approach dependent on the medical discipline sending the sample.