New concepts in systemic autoimmunity testing.

Diagnosis of systemic autoimmune diseases is highly complex, and it is becoming increasingly difficult to make assumptions about the functional roles and diagnostic significance of autoantibodies. The latter is mainly due to the fact that results from different assay systems are not interchangeable. A laboratory "gold standard" which helps the clinician to differentiate irrelevant autoimmune phenomena from significant autoimmune diseases at an early stage, is clearly missed.

Critical level and detection limit: performance measures for PCR-based assays.

In clinical diagnostic work, sensitivity and specificity are key assay features. In this note we introduce two clinically relevant statistical assay performance measures, the critical level (CL), and the detection limit (DL) for the PCR-based assay. To allow for easy access to these characteristics a Windows-based program has been developed.

Comparative study of different standardization concepts in quantitative competitive reverse transcription-PCR assays.

Four different standardization approaches based on a competitive reverse transcription (RT)-PCR assay were compared with a noncompetitive assay based on an external standard curve. Criteria for assessment were accuracy in quantitation, correctness of recovery, sensitivity, dynamic range, reproducibility, throughput, and convenience of sample handling. As a model system, we used the 5'-noncoding region of hepatitis C virus (HCV) for amplification in all quantitative RT-PCRs.

Expression of class I major histocompatibility complex antigens in Epstein-Barr virus-carrying lymphoblastoid cell lines and Burkitt lymphoma cells.

Epstein-Barr virus (EBV) carrying lymphoblastoid cell lines (LCLs) and EBV-positive Burkitt lymphoma (BL) cells were compared for their expression of class I antigens of the major histocompatibility complex. Five common BL lines, LCLs, pokeweed mitogen-stimulated blasts and resting B-cells from healthy donors, and eight pairs of BL cells and LCLs, each pair originating from one patient, were tested. Quantitative analysis was performed using a radioimmunoassay; qualitative aspects were studied by one- and two-dimensional gel electrophoresis.