Detection of Autoantibodies for Extractable Nuclear Antigens by LG Immunoblot Kit / 대한임상병리학회지

BACKGROUND: Identification of antibodies recognizing extractable nuclear antigens (ENAs) is use-ful in the diagnosis and characterization of a variety of connective tissue diseases. Recently, LG ENA Immunoblot (LGCI, Seoul, Korea) was introduced for detecting various autoantibodies to ENAs simultaneously. Performance of this kit was evaluated in this study. METHODS: Sera from 108 SLE patients and 103 RA patients were tested for the presence of spe-cific autoantibodies to ENAs by LG ENA Immunoblot and DID. Concordance rates in each autoan-tibody were obtained. After discordant results were resolved by EIA (ENA ELISA TEST SYSTEM, Zeus Scientific Inc., NJ, USA) and western blot (ANA Western Blot Immunoassay, IMMCO Diag-nostics Inc., NY, USA), sensitivity and specificity of LG ENA Immunoblot were evaluated. Between-day precision was also tested. RESULTS: Concordance rates in each autoantibody in two methods were as follows: anti-RNP (88.0%, 95/108; 100%, 103/103), anti-Sm (87.0%, 94/108; 97.1%, 100/103), anti-SSA (94.4%, 102/108; 99.0%, 102/103), anti-SSB (97.2%, 105/108; 98.1%, 101/103), anti-Scl70 (99.1%, 107/108; 100%, 103/103) in SLE and RA patients, respectively. Sensitivity and specificity of Immunoblot were 92.0% and 99.6% for anti-RNP, 100% and 99.6% for anti-Sm, 100% and 98.6% for anti-SSA, 90.0% and 98.5% for anti-SSB, and 100% and 100% for anti-Scl70, respectively. Between-day precisions were 100% in all anti-ENA antibodies. CONCLUSIONS: LG ENA Immunoblot showed good concordance rates with the conventional DID method and high sensitivity (>90%) and specificity (>98.5%) in detecting all kinds of anti-ENA autoantibodies. LG Immunoblot has another merit in that it can detect several autoantibodies simul-taneously. It is suggested that LG ENA Immunoblot can replace DID for anti-ENA detection without any problem.

Performance Evaluation of LG HBsAg Confirm Kit / 대한수혈학회지

BACKGROUND: The specificity of HBsAg enzyme immunoassay (EIA) has been previously reported between 95% and 100% for blood donor screening in Korea. Considering that Korea is highly endemic in HBV infection, it is highly recommended that blood donors showing true positive for HBsAg were permanently deferred from donation. Identification of false-positive results by a confirmation assay would be a necessary step for this purpose. This study was intended to evaluate LG HBsAg Confirm (LG Chemicals Corp., Seoul, Korea) kit as a confirmation test and know the positive predictive value for HBsAg screening results. METHODS: LG HBsAg Confirm reactivities were evaluated in 279 patients and 185 blood donor samples, all of which were positive in HBsAg EIA. Patients samples were positive in both HBsAg EIA and HBV DNA. Confirm positive was determined according to the following 2 step criteria: (1) the percent neutralization is 50% or more (first-step neutralization), or (2) if not, the percent neutralization after 1:1,000 dilution of original sample is 50% or more (second-step neutralization). RESULTS: LG HBsAg Confirm kit confirmed all 279 patients~ sera as positive. All of 185 blood donor samples showed true positive results. First-step neutralization confirmed 157 sera (33.8%) as positive and second-step neutralization confirmed 307 sera (66.2%) among 464 samples. CONCLUSION: Performance of LG HBsAg Confirm was so excellent that all the samples showing positive in both HBsAg EIA and HBV DNA tests could be determined as confirm positive.

Necessity of Anti-HBc and Anti-HBs Screening in Korean Blood Donation Program: Study using LG Anti-HBc and LG Anti-HBs ELISA Kit and HBV Nucleic Acid Amplification Test / 대한수혈학회지

BACKGROUND: Post-transfusion hepatitis B remains a risk for recipients of HBsAg negative bloods in Korea. The usefulness of anti-HBc screening for blood donors to reduce the risk of HBV transmission was evaluated in this study using LG Anti-HBc and LG Anti-HBs ELISA (LG Chemicals, Seoul, Korea) and HBV nucleic acid amplification test. METHOD: Sera from 2,274 HBsAg-negative blood donors were tested of anti-HBc and anti-HBs by LG Anti-HBc and LG Anti-HBs ELISA, respectively. Using 260 samples from HBsAg-negative blood donors and 62 FANA-positive samples, reactivity to LG Anti-HBc ELISA were compared with COBAS CORE Anti-HBc EIA (Roche Diagnostics, Basel, Switzerland). The precision of LG Anti-HBc was also tested. The nucleic acid amplification of 97 primary pools prepared from 2,274 samples was carried out, and then HBV presence was confirmed in individual samples. RESULT: Of 2,274 HBsAg-negative blood donors, 531 (23.4%) were positive for anti-HBc and 32 (1.4%) were anti-HBc positive/ anti-HBs negative. The concordance rate of LG Anti-HBc ELISA and COBAS was 97.8% (315/322). The intra-run and inter-run coefficient of variation was 4.7-10.2% and 2.5-11.4%, respectively. Thirteen pools showed initial positive in HBV PCR, but seven pools (53.8%) were finally found to be false positive. Of six true positive pools, seven samples were confirmed to have HBV DNA. The HBV detection rate was 6.3% (2/32) among donors whose results were anti-HBc positive/ anti-HBs negative. CONCLUSION: Among screen-negative blood donors, 6.3% of donors whose seroreactivity was anti-HBc positive/ anti-HBs negative were positive for HBV by nucleic acid amplification test, while donors showing such seroreactivity were only 1.4%. It is suggested that an introduction of anti-HBc and anti-HBs testing in Korean Blood Donation program be efficient to attain safety from HBV transmission.

Evaluation of LG Malaria Anti-PvTM for Diagnosis of Plasmodium vivax Malaria in the Republic of Korea / 대한임상병리학회지

BACKGROUND: In the Republic of Korea, Plasmodium vivax malaria, which had disappeared since 1984, re-emerged in 1993. Currently, malaria is becoming a serious public health problem in the Republic of Korea. The diagnosis of malaria has relied on microscopic examination such as thin and thick blood smears. However, even for expert microscopists, this test is a laborious and time-consuming procedure. Therefore, the development of a reliable, easy, and convenient diagnostic test is crucial. Recently, the LG malaria anti-PvTM enzyme-linked immunosorbent assay (ELISA) kit for the detection of a specific antibody against the merozoite surface protein (MSP) of P. vivax was developed. The aim of this study was to evaluate the diagnostic kit for P. vivax malaria in the Republic of Korea. METHODS: To determine the usefulness of the LG malaria anti-PvTM as a diagnostic kit for vivax malaria, a total of 59 serum samples from patients with P. vivax malaria were tested. The patients were diagnosed microscopically and the parasitemia index of their blood was calculated. Sera from 203 uninfected healthy blood donors, which were microscopically negative for Plasmodium vivax, were used as negative controls. RESULTS: The sensitivity and specificity of the LG malaria anti-PvTM were 98.31% (58/59) and 98.03% (199/203), respectively. The false-positive and false-negative rates were 1.97% (4/203) and 1.69% (1/59), respectively. CONCLUSIONS: The diagnostic kit, LG malaria anti-PvTM, might be a useful tool for diagnosis and screening of P. vivax malaria in Korea.