Influence of plasma interferences on screening coagulogram and performance evaluation of the automated coagulation analyzer sysmex® CS-2100i.

Background: Plasma interference is a problem for coagulation analyzers using a photo-optical detection method. Sysmex® CS-2100i is a fully-automated coagulation analyzer which has been developed to reduce this problem. Objective: To evaluate the influence of interferences on prothrombin time (PT), activated partial thromboplastin time (APTT), and fibrinogen analyzed by Sysmex® CS-2100i. The performance of this analyzer was also assessed in this study. Methods: Pooled plasma samples spiked with interfering substances including hemoglobin, bilirubin and lipid were used in the interference study. Real patients’ samples with these interferences were also tested. Control materials and pooled samples were used for precision, comparison, and carryover studies. Results: The PT, APTT, and fibrinogen could be analyzed in both plasma samples with interference added and real abnormal patients’ plasma samples. The deviation of PT, APTT, and fibrinogen levels was not obvious, except for an upward trend of fibrinogen level with increased hemoglobin. The highest %CV of PT, APTT, and fibrinogen were 1.24, 3.18, and 4.31, respectively for within-run and 2.32, 2.11, and 6.06, respectively for between-run precision analysis. The correlation coefficients of PT, APTT, and fibrinogen between Sysmex® CS-2100i and Sysmex® CA-1500 were 0.99, 0.99, and 0.98 with intra-class correlation coefficients of 0.99, 0.99, and 0.98 respectively. No significant carryover of specimen was observed. Conclusion: Sysmex® CS-2100i could analyze both samples with artificial interfering substance added and real abnormal patients’ samples. This machine also had an acceptable performance by our evaluation.

Prevalence of 60 kda and 52 kda Ro/SS-A autoantibodies in anti-Ro positive Thai sera in Siriraj Hospital.

BACKGROUND: Anti-Ro antibody may directly react against either Ro60 or Ro52 or both antigens. To be more applicable for routine laboratory practice, the specific antigen type for antibody detection should be identified before test application. OBJECTIVE: Investigate the prevalence of 60 kDa and 52 kDa Ro/SS-A antibodies in Thai patients' sera in Siriraj Hospital. MATERIAL AND METHOD: Specimens for anti-Ro were requested between June and December 2005. They were tested with EUROLINE test kit for prevalence determination. The principle of the test is a qualitative in-vitro-assay that contains test strips coated with parallel lines of 14 highly purified antigens. Of 84 specimens requested for anti-Ro antibody, 76 were collected and tested with the EUROLINE test kits and eight were excluded due to inadequacy. RESULTS: The prevalence of anti-Ro60 and anti-Ro52 of all sera tested for anti-Ro by EUROLINE test kit were 30% (95% CI: 20-40%) and 26% (95% CI: 16-36%), respectively; and, those in anti-Ro positive Thai sera were 82% (95% CI: 68-96%) and 71% (95% CI: 54-88%), respectively. The prevalence of anti-Ro52 alone in anti-Ro positive Thai sera and all specimens requested for anti-Ro was about 18% (95% CI: 4-32%) and 7% (95% CI: 1-13%), respectively. The agreement and Kappa value between the two methods were 0.9 and 0.77, respectively. The study suggests that the test for anti-Ro detection should provide both Ro 60 and Ro 52 antigens. CONCLUSION: The prevalence of both anti-Ro 60 and anti-Ro 52 were quite common, therefore, the test for this specific antibody should provide both antigens for antibody detection.

Synthesis of von willebrand factor antigen in chlamydophila pneumoniae-infected endothelial cells.

Objective: The main objective of our study was to evaluate the response of endothelial cells infected with Chlamydophila pneumoniae (C. pneumoniae), by using von Willebrand factor (vWf) antigen as a marker for endothelial damage and dysfunction. Another objective was to evaluate the effect of cycloheximide on C. pneumoniae infectivity and vWf secretion from human umbilical vein endothelial cells (HUVECs). Methods: HUVECs were harvested. After first passage, the HUVECs were inoculated with C. pneumoniae in three concentrations of cycloheximide (0, 1, and 2 µg/ml). At 24, 48, and 72 hours post-inoculation, supernatants from each HUVEC culture well were collected and measured for vWf antigen by sandwich ELISA as well as non-infected HUVECs were used as controls. C. pneumoniae infectivity was evaluated by indirect immunofluoresce technique and polymerase chain reaction. Results: The cycloheximide-treated HUVECs resulted in greater infection compared to the non-treated HUVECs. Means of vWf antigens from HUVECs infected with C. pneumoniae were not different from those of non-infected HUVECs. However, there was a significant change in vWf secretion when different concentrations of cycloheximide were used in the culture system. Conclusion: From our study, the results of vWf antigen secreted from HUVECs did not support the direct endothelial damage effect caused by C. pneumoniae infection. Therefore, vWf antigen is not a sensitive marker for this event. Furthermore, results from this study supported the infectious ability of C. pneumoniae on HUVECs and the importance of cycloheximide in improving the infectivity of this organism. However, the investigators had to use this substance cautiously, especially in protein synthesis study. Nevertheless, a non-variable dose of C. pneumoniae and the use of only one surrogate endothelial damage marker may limit the interpretation of this study.