Sensitivity and specificity of the high fluorescent lymphocyte count-gate on the Sysmex XE-5000 hematology analyzer for detection of peripheral plasma cells.

BACKGROUND: Plasma cells are one of the end products of the B-lymphocyte mediated immune response. These cells normally reside in the bone marrow or some peripheral lymphoid tissues. Increased numbers of plasma cells in the blood, usually indicates pathology such as infection, auto-immunity or haematological malignancy. Therefore, the ability to measure plasma cells (PCs) on an automated cell analyzer might be advantageous. METHODS: The performance of the Sysmex XE-5000 leukocyte differential channel [high fluorescent lymphocyte count (HFLC) area] was evaluated for the ability to detect plasma cells in peripheral blood and compared to the detection of plasma cells by flow cytometric analyses. RESULTS: Our results show that the HFL count from the XE-5000 correlates (R(2)=0.8) with the number of PCs in peripheral blood, but detects PCs with moderate to good sensitivity (88.9%) and specificity (87.8%). CONCLUSIONS: The Sysmex XE-5000 is suitable for screening blood samples for the presence of elevated number of plasma cells in peripheral blood, but the actual quantification needs to be confirmed by flow cytometry.

Analyses of CD27++ plasma cells in peripheral blood from patients with bacterial infections and patients with serum antinuclear antibodies.

The number of CD27++ plasma cells (PCs) in peripheral blood may be a valuable biomarker for systemic lupus erythematosus (SLE) disease management. More insights into the behavior of the PC population are, however, required to validate CD27 as a reliable biomarker. In the current study, we have monitored the PC compartment of patients with acute bacterial infections and patients with SLE and, in addition, examined the relationship between the presence of serum antinuclear antibodies (ANAs) and the number of peripheral PCs. Kinetic analyses in patients with bacterial infection revealed a 10-60-fold expansion of the CD27++ PC compartment that peaked at day 2-5 and returned toward normal values at day 7-9 after hospital admission. The transient expansion of the PC population appeared to be a late phenomenon in the process of recovering from a bacterial infection. SLE subjects had significantly increased frequencies of PCs compared with patients suspected of a connective tissue disease and healthy controls. In patients suspected of a connective tissue disease, no relationship was found between the presence of serum ANAs and the number of CD27++ PCs. Additionally, the presence of serum ANAs was not associated with abnormalities in other peripheral B-cell subsets. It remains to be established at which stage of SLE development the expansion of the PC compartment is initiated.

Detection of shortened activated partial thromboplastin times: an evaluation of different commercial reagents.

INTRODUCTION: Abnormally shortened activated partial thromboplastin times (aPTT) are associated with significantly increased risk of thrombotic disorders and in-hospital mortality. Shortened aPTTs have been related to increased levels of factor (F) VIII and thrombin-antithrombin complex (TAT). In the current study, four different commercial aPTT reagents were evaluated for their performance to detect shortened aPTTs. MATERIALS AND METHODS: aPTT of 400 patients was determined using Actin-FS (Dade Behring), APTT-SP (Instrumentation Laboratory), Automated-APTT (bioMerieux) and Platelin-LS (bioMerieux) reagents. FVIII, FIX, FXI and TAT levels were measured in shortened and normal aPTT samples. RESULTS: An association between shortened aPTTs and elevated levels of coagulation factors (FVIII, FIX and FXI) and thrombin generation (TAT) was found with all tested aPTT reagents. Method-comparison studies demonstrated good agreement between Instrumentation Laboratory and bioMerieux reagents. However, 53 to 59% of the patients with a shortened aPTT measured with Actin-FS reagent was determined as a normal aPTT with APTT-SP, Automated-APTT and Platelin-LS reagents. These patients had increased levels of FVIII, FIX and FXI and moderately increased levels of TAT. CONCLUSION: Overall, an acceptable agreement between the different commercial reagents was found with respect to detection of short aPTTs. However, a disparity between some of reagents existed. Actin-FS reagent appeared to be more sensitive in inducing shortened aPTT reactions than APTT-SP, Automated-APTT and Platelin-LS reagents.