Elderly kidney transplant recipients have favorable outcomes but increased infection-related mortality

The number of elderly patients with end-stage kidney disease has been increasing, but the outcomes of kidney transplants (KT) remain poorly understood in elderly patients. Therefore, we evaluated the clinical outcomes of elderly KT recipients and analyzed the impact of elderly donors. Methods: This retrospective cohort study included patients who underwent KT between 2000 and 2019. KT recipients were divided into four groups according to a combination of recipient and donor age (≥60 or <60 years); elderly recipients: old-to-old (n = 46) and young-to-old (n = 83); young recipients: old-to-young (n = 98) and young-to-young (n = 796). We compared the risks of mortality, graft failure, and acute rejection between groups using Cox regression analysis. Results: The incidence of delayed graft function, graft failure, and acute rejection was not different among groups. Annual mean tacrolimus trough level was not lower in elderly recipients than young recipients during 10-year follow-up. Mortality was significantly higher in elderly recipients (p = 0.001), particularly infection-related mortality (p < 0.001). In multivariable Cox regression analysis, old-toold and young-to-old groups had increased risk of mortality (adjusted hazard ratio [aHR], 2.89; 95% confidence interval [CI], 1.14– 7.32; p = 0.03; aHR, 3.06; 95% CI, 1.51–6.20; p = 0.002). However, graft failure and acute rejection risks were not increased in elderly recipients. Conclusion: In elderly recipients, graft survival and acute rejection-free survival were not inferior to those of young recipients. However, mortality, especially risk of infection-related death, was increased in elderly recipients. Thus, low immunosuppression intensity might help decrease mortality in elderly recipients.

Stratification of Nuclear Homogeneous Patterns on HEp-2 Cells Based on Neutrophil Nuclear Staining / 전남의대학술지

Antinuclear antibody (ANA) testing is used to diagnose systemic autoimmune rheumatic disease (SARD). Nuclear homogeneous patterns on ANA-HEp-2 cells can result from anti-double-stranded DNA (dsDNA), anti-nucleosome, anti-histone, anti-Scl-70, or anti-dense fine speckles 70 (DFS70) antibodies (Abs). This study aimed to find a way to discriminate DFS70 Abs from others by way of assessing neutrophil nuclear staining on anti-neutrophil cytoplasmic antibody (ANCA) testing. Nuclear staining on ANCAneutrophils was assessed to stratify nuclear homogeneous patterns on ANA-HEp-2 cells. Enrolled subjects included (1) young individuals with a dense fine speckled pattern on ANA testing (young non-SARD group, n=71) and patients with (2) systemic lupus erythematosus (SLE group, n=35); (3) rheumatoid arthritis possibly with histone, nucleosome Abs, and others (RA group, n=51); and (4) diffuse systemic sclerosis with Scl-70 Abs (diffuse SSc group, n=19). Negative rates (95% confidence interval) of neutrophil nuclear staining were 97.2% (90.2%-99.7%) in the young non-SARD group, 2.9% (0.1%-14.9%) in the SLE group, 3.9% (0.5%-13.5%) in the RA group, and 47.4% (24.5%-71.1%) in the diffuse SSc group. The negative rate of the young non-SARD group was significantly higher than those of the other groups (all p<0.05). In conclusion, this study suggests that the assessment of nuclear staining on ANCA-neutrophils can help to stratify nuclear homogeneous patterns on ANA-HEp-2 cells and thus to determine whether the ANA pattern is attributed to DFS70 Abs, which can be found in healthy individuals, especially in young individuals.

Mycophenolic Acid Trough Concentration and Dose Are Associated with Hematologic Abnormalities but Not Rejection in Kidney Transplant Recipients

Background@#Little is known regarding the safe fixed dose of mycophenolic acid (MPA) for preventing biopsy-proven acute rejection (BPAR) in kidney transplant recipients (KTRs). We investigated the correlation of MPA trough concentration (MPA C0) and dose with renal transplant outcomes and adverse events. @*Methods@#This study included 79 consecutive KTRs who received MPA with tacrolimus (TAC) and corticosteroids. The MPA C0 of all the enrolled KTRs was measured, which was determined monthly by using particle-enhanced turbidimetric inhibition immunoassay for 12 months, and clinical data were collected at each time point. The clinical endpoints included BPAR, any cytopenia, and BK or cytomegalovirus infections. @*Results@#No differences in MPA C0 and dose were observed between KTRs with or without BPAR or viral infections under statistically comparable TAC concentrations. MPA C0 was significantly higher in patients with leukopenia (P = 0.021) and anemia (P = 0.002) compared with those without cytopenia. The MPA dose was significantly higher in patients with thrombocytopenia (P = 0.002) compared with those without thrombocytopenia. MPA C0 ≥ 3.5 μg/mL was an independent risk factor for leukopenia (adjusted odds ratio [AOR], 3.80; 95% confidence interval [CI], 1.24–11.64; P = 0.019) and anemia (AOR, 5.90; 95% CI, 1.27–27.51; P = 0.024). An MPA dose greater than the mean value of 1,188.8 mg/day was an independent risk factor for thrombocytopenia (AOR, 3.83; 95% CI, 1.15–12.78; P = 0.029). However, an MPA dose less than the mean value of 1,137.3 mg/day did not increase the risk of BPAR. @*Conclusion@#Either a higher MPA C0 or dose is associated with an increased risk of cytopenia, but neither a lower MPA C0 nor dose is associated with BPAR within the first year of transplantation. Hence, a reduced MPA dose with TAC and corticosteroids might be safe in terms of reducing hematologic abnormalities without causing rejection.

Natural soluble human leukocyte antigen class I in donor serum neutralizes donor-specific HLA alloantibodies in recipient serum

Background@#Human leukocyte antigen (HLA) molecules are cell-bound but can be identified in a soluble form. These soluble HLA (sHLA) molecules have an immunomodulatory function. We investigated whether natural sHLA in donor serum can neutralize donor-specific HLA alloantibodies (DSAs) in recipient serum. @*Methods@#Neutralizing effects of donor serum on DSAs in recipient serum were measured using inhibition assay principle of flow cytometric crossmatch (FCXM), performed using sera from 143 kidney transplant recipients and their donors. The adding of donor serum to recipient serum yielded lower mean fluorescence intensity (MFI) ratios (test/control) than when diluent was added [Roswell Park Memorial Institute (RPMI) or third-party serum], which was presumed to be caused by the neutralizing effects of sHLA. @*Results@#In the recipient group with class I DSAs alone (N=14), donor serum addition to recipient serum resulted in lower T cell MFI ratios [2.25 (1.31‒32.51)] than those observed on RPMI addition [3.04 (1.33‒125.39), P ＜0.05]. In the recipient group with class II DSAs alone (N=27), donor serum addition showed no significant difference in B cell MFI ratios [5.03 (1.41‒103.53)] compared to diluent addition: RPMI [4.50 (1.34‒145.98)] or third-party serum [5.08 (1.44‒138.47)], P ＞0.05 for both. @*Conclusion@#Using inhibition FCXM, we verified that natural sHLA class I in donor serum neutralizes DSAs in recipient serum. However, no neutralizing effects of sHLA class II were revealed in this study. These potentially beneficial effects of sHLA infused via blood-derived products should be considered when desensitizing highly HLA-sensitized patients.

Comparison of Transplant Outcomes for Low-level and Standard-level Tacrolimus at Different Time Points after Kidney Transplantation

BACKGROUND: Optimal tacrolimus (TAC) trough levels for different periods after kidney transplantation (KT) has not been definitely established. This study aimed to investigate transplant outcomes of low-level (LL) and standard-level (SL) TAC according to post-transplant period. METHODS: A total of 278 consecutive kidney transplant recipients (KTRs) receiving TAC-based immunosuppression were divided into LL and SL-TAC groups (4–7 and 7–12 ng/mL for 0–2 months, 3–6 and 6–10 ng/mL for 3–6 months, 2–5 and 5–8 ng/mL for 7–12 months, respectively) according to TAC trough level at each period. We compared estimated glomerular filtration rate (eGFR), biopsy-proven acute rejection (BPAR), de novo donor-specific antibody (dnDSA), calcineurin inhibitor (CNI) toxicity, opportunistic infection, and allograft survival. RESULTS: SL-TAC group showed significantly higher mean eGFR at 0–2 months than LL-TAC group (72.1 ± 20.3 vs. 64.2 ± 22.7 mL/min/1.73m2; P = 0.003). Incidence of BPAR at 7–12 months was significantly lower in SL-TAC group than in LL-TAC group (0.0% vs. 3.9%; P = 0.039). Patients with persistent SL-TAC lasting 12 months showed higher eGFR at 7–12 months than those with persistent LL-TAC (65.5 ± 13.0 vs. 57.9 ± 13.9 mL/min/1.73m2; P = 0.007). No significant differences in dnDSA, CNI toxicity, serious infections, or allograft survival were observed. CONCLUSIONS: Maintenance of proper TAC trough level after 6 months could reduce BPAR without adverse drug toxicities in KTRs. Moreover, persistent SL-TAC during the first year after KT might have a beneficial effect on a trend for a lower incidence of dnDSA and better renal allograft function.

Characteristics and Clinical Significance of de novo Donor-Specific Anti-HLA Antibodies after Kidney Transplantation

BACKGROUND: The association of de novo donor-specific anti-human leukocyte antigens (HLA) antibodies (DSA) and development of antibody-mediated rejection (AMR) in kidney transplant recipients (KTRs) is still undetermined. METHODS: We prospectively screened de novo DSA in 167 KTRs during 32 months after kidney transplantation (KT). Timing of DSA detection was at 3, 6, and 12 months post-transplant and annually thereafter and when clinically indicated. DSA levels were determined by Luminex assays and expressed as mean fluorescence intensity (MFI). We evaluated the incidence, characteristics of DSA, and association between DSA and tacrolimus trough levels or AMR. RESULTS: De novo DSA developed in 16 KTRs (9.6%) and acute AMR occurred more commonly in KTRs with de novo DSA compared to KTRs without de novo DSA (18.8% vs. 0%, P < 0.001). All de novo DSA were against class II antigens. The mean number of DSA was 1.8 ± 1.2 and the average MFI of DSA was 7,399 ± 5,470. Tacrolimus trough level during the first 0–2 months after KT was an independent predictor of DSA development (hazard ratio, 0.70; 95% confidence interval, 0.50–0.99; P = 0.043). No differences were found in the number of DSA, average MFI of DSA, and tacrolimus levels during the first year between de novo DSA-positive KTRs with AMR and those without AMR. CONCLUSION: The results of our study suggest that monitoring of DSA and maintaining proper tacrolimus levels are essential to prevent AMR during the initial period after KT.

Neutrophil oxidative burst as a diagnostic indicator of IgG-mediated anaphylaxis

BACKGROUND: IgG-mediated anaphylaxis occurs after infusion of certain monoclonal antibody-based therapeutics. New in vitro tests are urgently needed to diagnose such reactions. We investigated whether allergens trigger neutrophil oxidative burst (OB) and if neutrophil OB occurs due to allergen-specific IgG (sIgG). METHODS: Neutrophil OB was measured by dihydrorhodamine 123 flow cytometry using a leukocyte suspension spiked with a very small patch of the allergen crude extract, Dermatophagoides farinae (Der f). The mean fluorescence intensity ratio of stimulated to unstimulated samples was calculated as the neutrophil oxidative index (NOI). RESULTS: The Der f-specific NOI (Der f-sNOI) showed a time-dependent increase after Der f extract addition. At 15 min activation, higher Der f-sIgG levels were associated with lower Der f-sNOI values in 31 subjects (P < 0.05). This inverse relationship occurs due to the initial blocking effect of free Der f-sIgG. Additionally, neutrophil OB was nearly absent (Der f-sNOI of −1) in two cases: a subject with undetectable Der f-sIgG levels and washed leukocyte suspensions deprived of Der f-sIgG. CONCLUSION: Allergens can trigger neutrophil OB via preexisting allergen-sIgG. Neutrophil OB can be easily measured in a leukocyte suspension spiked with the allergen. This assay can be used to diagnose IgG-mediated anaphylaxis.

Increased Circulating T Lymphocytes Expressing HLA-DR in Kidney Transplant Recipients with Microcirculation Inflammation

We consecutively enrolled 82 kidney transplant recipients (KTRs) with stable renal function and 24 KTRs who underwent indication biopsy to compare the histological grading of renal allografts with the activity of circulating T lymphocyte subsets and monocytes determined by flow cytometry, which were obtained at 2 weeks after kidney transplantation (KT) and at the time of indication biopsy, respectively. The sum of the scores of glomerulitis (g) + peritubular capillaritis (ptc), inflammation (i) + tubulitis (t), interstitial fibrosis (ci) + tubular atrophy (ct), and fibrointimal thickening (cv) + arteriolar hyaline thickening (ah) was used to assign a histological grade to the renal allograft samples. The frequencies of CD4⁺HLA-DR⁺/CD4⁺ T cells and CD8⁺HLA-DR⁺/CD8⁺ T cells were significantly increased in KTRs with a microcirculation inflammation (MI) sum score ≥ 1 when compared with KTRs with an MI sum score = 0 as well as stable KTRs. In these 2 subsets, only CD4⁺HLA-DR⁺/CD4⁺ T cells were positively correlated with MI sum scores. Analysis using the receiver operating characteristic (ROC) curve showed that antibody-mediated rejection (AMR) could be predicted with a sensitivity of 80.0% and a specificity of 94.7%, using a cutoff value of 29.6% frequency of CD4⁺HLA-DR⁺/CD4⁺ T cells. MI was significantly associated with an increased frequency of activated T lymphocytes expressing human leukocyte antigen-antigen D related (HLA-DR). Further studies should focus on validating the utility of circulating CD4⁺HLA-DR⁺/CD4⁺ T cells as a noninvasive, immunologic monitoring tool for the prediction of AMR.

Basophil Markers for Identification and Activation in the Indirect Basophil Activation Test by Flow Cytometry for Diagnosis of Autoimmune Urticaria

BACKGROUND: The indirect basophil activation test using flow cytometry is a promising tool for autoimmune urticaria diagnosis. We aimed to identify better donor basophils (from atopic vs. non-atopic donors and interleukin-3 primed vs. unprimed basophils) and improve basophil identification and activation markers (eotaxin CC chemokine receptor-3 [CCR3] vs. CD123 and CD63 vs. CD203c). METHODS: Donor basophils were obtained from non-atopic and atopic group O donors. Positive control sera were artificially prepared to simulate autoimmune urticaria patients' sera. Patient sera were obtained from nine children with chronic urticaria. Assay sensitivity was compared among each variation by using positive control sera (n=21), applying cutoff values defined from negative control sera (n=20). RESULTS: For basophil identification, a combination of CCR3 and CD123 markers revealed a higher correlation with automated complete blood count (r=0.530) compared with that observed using CD123 (r=0.498) or CCR3 alone (r=0.195). Three activation markers on the atopic donor basophils attained 100% assay sensitivity: CD203c on unprimed basophils, CD63+CD203+ or CD63 alone on primed basophils; however, these markers on the non-atopic donor basophils attained lower assay sensitivity. CONCLUSIONS: For basophil identification markers, a combination of CD123 and CCR3 is recommended, while CD123 alone may be used as an alternative. Donor basophils should be obtained from an atopic donor. For basophil activation markers, either CD203c alone on unprimed basophils or CD203c and CD63 on primed basophils are recommended, while CD63 alone on primed basophils may be used as an alternative.

Reply to the Letter to the Editor by Dr. Chirumbolo

No abstract available.

Highly Sensitive and Novel Point-of-Care System, aQcare Chlamydia TRF Kit for Detecting Chlamydia trachomatis by Using Europium (Eu) (III) Chelated Nanoparticles

BACKGROUND: The bacterium Chlamydia trachomatis is one of the leading causes of sexually transmitted diseases worldwide. Since no simple and effective tool exists to diagnose C. trachomatis infections, we evaluated a novel point-of-care (POC) test, aQcare Chlamydia TRF kit, which uses europium-chelated nanoparticles and a time-resolved fluorescence reader. METHODS: The test performance was evaluated by comparing the results obtained using the novel POC testing kit with those obtained using a nucleic acid amplification test (NAAT), using 114 NAAT-positive and 327 NAAT-negative samples. RESULTS: The cut-off value of the novel test was 20.8 with a detection limit of 0.27 ng/mL. No interference or cross-reactivity was observed. Diagnostic accuracy showed an overall sensitivity of 93.0% (106/114), specificity of 96.3% (315/327), positive predictive value (PPV) of 89.8% (106/118), and negative predictive value (NPV) of 97.5% (315/323). The sensitivity of the novel test was much higher than that of currently available POC tests. Furthermore, the relative ease and short turnaround time (30 min) of this assay enables C. trachomatis-infected individuals to be treated without a diagnostic delay. CONCLUSIONS: This simple and novel test is a potential tool to screen a larger population, especially those in areas with limited resources.

Flow Cytometric Human Leukocyte Antigen-B27 Typing with Stored Samples for Batch Testing

BACKGROUND: Flow cytometry (FC) HLA-B27 typing is still used extensively for the diagnosis of spondyloarthropathies. If patient blood samples are stored for a prolonged duration, this testing can be performed in a batch manner, and in-house cellular controls could easily be procured. In this study, we investigated various methods of storing patient blood samples. METHODS: We compared four storage methods: three methods of analyzing lymphocytes (whole blood stored at room temperature, frozen mononuclear cells, and frozen white blood cells [WBCs] after lysing red blood cells [RBCs]), and one method using frozen platelets (FPLT). We used three ratios associated with mean fluorescence intensities (MFI) for HLAB27 assignment: the B27 MFI ratio (sample/control) for HLA-B27 fluorescein-5-isothiocyanate (FITC); the B7 MFI ratio for HLA-B7 phycoerythrin (PE); and the ratio of these two ratios, B7/B27 ratio. RESULTS: Comparing the B27 MFI ratios of each storage method for the HLA-B27+ samples and the B7/B27 ratios for the HLA-B7+ samples revealed that FPLT was the best of the four methods. FPLT had a sensitivity of 100% and a specificity of 99.3% for HLA-B27 assignment in DNA-typed samples (N=164) when the two criteria, namely, B27 MFI ratio >4.0 and B7/B27 ratio <1.5, were used. CONCLUSIONS: The FPLT method was found to offer a simple, economical, and accurate method of FC HLA-B27 typing by using stored patient samples. If stored samples are used, this method has the potential to replace the standard FC typing method when used in combination with a complementary DNA-based method.

Flow Cytometric Human Leukocyte Antigen-B27 Typing with Stored Samples for Batch Testing

BACKGROUND: Flow cytometry (FC) HLA-B27 typing is still used extensively for the diagnosis of spondyloarthropathies. If patient blood samples are stored for a prolonged duration, this testing can be performed in a batch manner, and in-house cellular controls could easily be procured. In this study, we investigated various methods of storing patient blood samples. METHODS: We compared four storage methods: three methods of analyzing lymphocytes (whole blood stored at room temperature, frozen mononuclear cells, and frozen white blood cells [WBCs] after lysing red blood cells [RBCs]), and one method using frozen platelets (FPLT). We used three ratios associated with mean fluorescence intensities (MFI) for HLAB27 assignment: the B27 MFI ratio (sample/control) for HLA-B27 fluorescein-5-isothiocyanate (FITC); the B7 MFI ratio for HLA-B7 phycoerythrin (PE); and the ratio of these two ratios, B7/B27 ratio. RESULTS: Comparing the B27 MFI ratios of each storage method for the HLA-B27+ samples and the B7/B27 ratios for the HLA-B7+ samples revealed that FPLT was the best of the four methods. FPLT had a sensitivity of 100% and a specificity of 99.3% for HLA-B27 assignment in DNA-typed samples (N=164) when the two criteria, namely, B27 MFI ratio >4.0 and B7/B27 ratio <1.5, were used. CONCLUSIONS: The FPLT method was found to offer a simple, economical, and accurate method of FC HLA-B27 typing by using stored patient samples. If stored samples are used, this method has the potential to replace the standard FC typing method when used in combination with a complementary DNA-based method.

Two Cases of Autoimmune Neutropenia of Infancy / 임상소아혈액종양

Autoimmune neutropenia of infancy (AIN) is caused by increased peripheral destruction of neutrophils as a result of antibodies in patients' blood that are directed against their own neutrophils. Due to non-specific symptoms, benign clinical courses, and cumbersome diagnostic tests, AIN are commonly undetected. Antineutrophil antibody test for diagnosis of AIN has recently become available. Compared to its relatively lower absolute neutrophil count (ANC), the clinical course of AIN is mostly benign. Therefore, although treatment is not usually necessary for AIN, it is applicable in order to rule out other significant diseases, such as severe congenital neutropenia (SCN), which can be transformed to myelodysplastic syndrome or acute myelocytic leukemia. For this reason, several treatments can be used for neutropenia: granulocyte-colony stimulating factor (G-CSF) for SCN, trimethoprim and sulfamethoxazole (TMP-SMX) for prophylaxis. Here we report on two cases of AIN confirmed by indirect immunofluorescence test using flow cytometry.

Two Cases of Autoimmune Neutropenia of Infancy / 임상소아혈액종양

Autoimmune neutropenia of infancy (AIN) is caused by increased peripheral destruction of neutrophils as a result of antibodies in patients' blood that are directed against their own neutrophils. Due to non-specific symptoms, benign clinical courses, and cumbersome diagnostic tests, AIN are commonly undetected. Antineutrophil antibody test for diagnosis of AIN has recently become available. Compared to its relatively lower absolute neutrophil count (ANC), the clinical course of AIN is mostly benign. Therefore, although treatment is not usually necessary for AIN, it is applicable in order to rule out other significant diseases, such as severe congenital neutropenia (SCN), which can be transformed to myelodysplastic syndrome or acute myelocytic leukemia. For this reason, several treatments can be used for neutropenia: granulocyte-colony stimulating factor (G-CSF) for SCN, trimethoprim and sulfamethoxazole (TMP-SMX) for prophylaxis. Here we report on two cases of AIN confirmed by indirect immunofluorescence test using flow cytometry.

A Case of a False-Positive Anti-Myeloperoxidase Antibody ELISA in a Patient with Hypothyroidism / 전남의대학술지

We present a case of a false-positive anti-myeloperoxidase (MPO) antibody result on an ELISA in a patient with anti-thyroid microsomal antibody (TMA)-positive hypothyroidism. A 41-year-old woman presented with dyspnea on exertion. The initial evaluation revealed pericardial effusion associated with hypothyroidism. In addition, microscopic hematuria with normal renal function and positive cytoplasmic anti-neutrophil cytoplasmic antibodies (c-ANCA) on immunofluorescent assay were found. In further evaluation, elevated anti-TMA and MPO antibodies by ELISA. While no definite signs of vasculitis were present, the clinical state improved with thyroid hormone replacement and diuretics. Anti-MPO antibody was still positive in the follow-up tests, and microscopic hematuria persisted. On the basis of previous reports that thyroid peroxidase and MPO molecules contain cross-reactive epitopes that are exposed in denaturated molecules, we suggest that in a patient with anti-TMA-positive hypothyroidism, anti-MPO antibody might also be positive on ELISA without clinical signs of vasculitis.

Analysis of Positive Flow Cytometric Crossmatch in Organ Transplantation

BACKGROUND: Pretransplant HLA crossmatch is one of the most important parts in solid organ transplantation. Flow cytometic crossmatch (FCXM) is more sensitive than anti-human globulin enhanced complement dependent lymphocytotoxicity (AHG-CDC) in detecting anti-HLA antibodies. We compared the results of the two methods and analyzed the FCXM-positive cases in various aspects. METHODS: Sera from 212 patients were tested for the detection of anti-HLA antibodies by FCXM and 188 of them were also tested by AHG-CDC assay. The results were analyzed in relation to their histories of pregnancy, transfusion or organ transplantation and also according to the donor patient relationships. We compared the FCXM results obtained before and after desensitization therapy (using plasmapheresis and anti-CD20 antibody) in 5 sensitized patients. RESULTS: Concordance of the results between the two methods was 88.8% (167/188). FCXM results correlated with history of pregnancy, but not with that of transfusion. When the patients were divided into 4 groups according to donor-patient relationships, the T cell FCXM mean fluorescence intensity (MFI) ratio (sample/control) was significantly higher in the husband-to-multiparous wife group compared to the other 3 groups (children-to-mother, unrelated donor-to-multipara, and the rests). After desensitization therapy, MFI ratios of T cell FCXM decreased and those of B cell FCXM increased, probably due to rituximab effect, in all 5 patients. CONCLUSIONS: FCXM using a MFI ratio, has a higher sensitivity than AHG-CDC in detection of donor specific antibodies. Also it can be useful in monitoring antibody levels during desensitization therapy.

Clinical Usefulness of Combined Anti-tuberculosis Antibody Test and Interferon-gamma Release Assay for the Diagnosis of Tuberculosis

BACKGROUND: For the diagnosis of tuberculosis (TB), a variety of tests based on the patients' immune response has been introduced. We evaluated the clinical usefulness of combined anti-tuberculosis antibody (anti-TB Ab) test and Interferon-gamma release assay (IGRA), evaluating humoral and cellular immune response to Mycobacterium tuberculosis, respectively. METHODS: Among patients tested for IGRA, 78 patients diagnosed as TB and treated with anti-TB drug and 80 non-TB patients were included in this study. We used QuantiFERON-TB GOLD (QFT, Cellestis limited, Australia) for IGRA and an immunochromatographic assay, Easy Test TB (ASAN PHARM, Korea), for anti-TB Ab test. RESULTS: The sensitivity, specificity, and positive and negative predictive values of Easy Test TB were 23.1%, 98.8%, 94.7% and 56.8%, respectively. QFT had a significantly higher sensitivity than Easy Test TB (67.9% vs. 23.1%; P<0.05). The agreement between the two assays was poor (69.6%, k=0.190). Of the 18 cases with positive Easy Test TB, six (33%) showed negative QFT results. The combination of Easy Test TB and QFT had a significantly higher sensitivity than single QFT (75.6%, vs. 67.9%; P=0.031). CONCLUSIONS: The combination of Easy Test TB and QFT could be used to aid in a rapid diagnosis and early treatment of TB.

A Case of a False-Positive Anti-Myeloperoxidase Antibody ELISA in a Patient with Hypothyroidism / 전남의대학술지

We present a case of a false-positive anti-myeloperoxidase (MPO) antibody result on an ELISA in a patient with anti-thyroid microsomal antibody (TMA)-positive hypothyroidism. A 41-year-old woman presented with dyspnea on exertion. The initial evaluation revealed pericardial effusion associated with hypothyroidism. In addition, microscopic hematuria with normal renal function and positive cytoplasmic anti-neutrophil cytoplasmic antibodies (c-ANCA) on immunofluorescent assay were found. In further evaluation, elevated anti-TMA and MPO antibodies by ELISA. While no definite signs of vasculitis were present, the clinical state improved with thyroid hormone replacement and diuretics. Anti-MPO antibody was still positive in the follow-up tests, and microscopic hematuria persisted. On the basis of previous reports that thyroid peroxidase and MPO molecules contain cross-reactive epitopes that are exposed in denaturated molecules, we suggest that in a patient with anti-TMA-positive hypothyroidism, anti-MPO antibody might also be positive on ELISA without clinical signs of vasculitis.

A Simple Method to Prepare Anti-Neutrophil Cytoplasmic Antibody Slides / 임상검사와정도관리

BACKGROUND: Neutrophils fixed on a slide are used in indirect immunofluorescence assay (IIF) for anti-neutrophil cytoplasmic antibody (ANCA). A simple method to prepare ANCA slides is described in this report. METHODS: This method uses an overlay method to separate WBC from EDTA whole blood and Octospottrade mark kits to cytocentrifuge WBC onto 8-well slides. This in-house ANCA IIF was compared with commercial ANCA IIF using 40 sera, and with enzyme linked immunosorbent assay for anti-myeloperoxidase (MPO) antibody (MPO ELISA) using 117 sera. RESULTS: In ANCA IIF parallel tests using 10 positive and 30 negative sera, in-house slides were in good qualitative agreement, 97.5% (39/40) with commercial kits (kappa=0.93). Fluorescence pattern and intensity of positive reaction was also highly concordant between two methods. In MPO ELISA positive cases, the positivity rate of in-house ANCA IIF was 97.8% (45/46), which accounts for its assay sensitivity for the presence of anti-MPO antibody. CONCLUSIONS: In-house ANCA slides was convenient and cost-efficient to be prepared. As these slides were found to have acceptable agreement and sensitivity as compared with commercial kits, in-house ANCA IIF is considered to be useful to screen ANCA in combination with MPO ELISA in routine clinical laboratory practice.