Imprecision and quality control in immunophenotyping of lymphocyte subsets in peripheral blood

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.