Characterization of a novel mouse platelet transfusion model

BACKGROUND AND OBJECTIVES

Platelet transfusions are increasing with medical advances. Based on FDA criteria, platelet units are assessed by in vitro measures; however, it is not known how platelet processing and storage duration affect function in vivo. Our study's aim was to develop a novel platelet transfusion model stored in mouse plasma that meets FDA criteria adapted to mice, and transfused fresh and stored platelets are detectable in clots in vivo.

STUDY DESIGN AND METHODS

Platelet units stored in mouse plasma were prepared using a modified platelet-rich plasma (PRP) collection protocol. Characteristics of fresh and stored units, including pH, cell count, in vitro measures of activity, including activation and aggregation, and post-transfusion recovery (PTR), were determined. Lastly, a tail transection assay was conducted using mice transfused with fresh or stored units, and transfused platelets were identified by confocal imaging.

RESULTS

Platelet units had acceptable platelet and white cell counts and were negative for bacterial contamination. Fresh and 1-day stored units had acceptable pH; the platelets were activatable by thrombin and adenosine diphosphate, agreeable with thrombin, had acceptable PTR, and were present in vivo in clots of recipients after tail transection. In contrast, 2-day stored units had clinically unacceptable quality.

CONCLUSION

We developed mouse platelets for transfusion analogous to human platelet units using a modified PRP collection protocol with maximum storage of 1 day for an 'old' unit. This provides a powerful tool to test how process modifications and storage conditions affect transfused platelet function in vivo.

Characterization of a Novel Mouse Platelet Transfusion Model

BACKGROUND

Platelet transfusions are increasing with advances in medical care. Based on FDA criteria, platelet units are assessed by in vitro measures; however, it is not known how platelet processing and storage duration affect function in vivo. To address this, we developed a novel platelet transfusion model that meets FDA criteria adapted to mice, and transfused fresh and stored platelets are detected in clots in vivo.

STUDY DESIGN AND METHODS

Platelet units stored in mouse plasma were prepared using a modified platelet rich plasma collection protocol. Characteristics of fresh and stored units, including pH, cell count, in vitro measures of activity, including activation and aggregation, and post-transfusion recovery (PTR), were determined. Lastly, a tail transection assay was conducted using mice transfused with fresh or stored units, and transfused platelets were identified by confocal imaging.

RESULTS

Platelet units had acceptable platelet and white cell counts and were negative for bacterial contamination. Fresh and 1-day stored units had acceptable pH; the platelets were activatable by thrombin and ADP, aggregable with thrombin, had acceptable PTR, and were present in vivo in clots of recipients after tail transection. In contrast, 2-day stored units had clinically unacceptable quality.

DISCUSSION

We developed mouse platelets for transfusion analogous to human platelet units using a modified platelet rich plasma collection protocol with maximum storage of 1 day for an "old" unit. This provides a powerful tool to test how process modifications and storage conditions affect transfused platelet function in vivo.

Evaluation of a Zoonotic Orthopoxvirus PCR Assay for the Detection of Mpox Virus Infection

An epidemic caused by an outbreak of mpox (formerly monkeypox) in May 2022 rapidly spread internationally, requiring an urgent response from the clinical diagnostics community. A detailed description of the clinical validation and implementation of a laboratory-developed real-time PCR test for detecting nonvariola Orthopoxvirus-specific DNA based on the newly designed RealStar Zoonotic Orthopoxvirus assay is presented. The validation was performed using an accuracy panel (n = 97) comprising skin lesion swabs in universal transport media and from mpox virus genomic DNA spiked into pooled mpox virus-negative remnant universal transport media of lesion specimens submitted for routine clinical testing in the NewYork-Presbyterian Hospital clinical laboratory system. Accuracy testing demonstrated excellent assay agreement between expected and observed results and comparable diagnostic performance to three different reference tests. Analytical sensitivity with 95% detection probability was 126 copies/mL, and analytical specificity, clinical sensitivity, and clinical specificity were 100%. In summary, the RealStar Zoonotic Orthopoxvirus assay provides a sensitive and reliable method for routine diagnosis of mpox infections.

Assessing respiratory viral exclusion and affinity interactions through co-infection incidence in a pediatric population during the 2022 resurgence of influenza and RSV

Introduction

In the Northeast US, respiratory viruses such as influenza and respiratory syncytial virus (RSV), which were largely suppressed by COVID-19-related social distancing, made an unprecedented resurgence during 2022, leading to a substantial rise in viral co-infections. However, the relative rates of co-infection with seasonal respiratory viruses over this period have not been assessed.

Methods

Here we reviewed multiplex respiratory viral PCR data (BioFire FilmArray™ Respiratory Panel v2.1 [RPP]) from patients with respiratory symptoms presenting to our medical center in New York City to assess co-infection rates of respiratory viruses, which were baselined to total rates of infection for each virus. We examined trends in monthly RPP data from adults and children during November 2021 through December 2022 to capture the full seasonal dynamics of respiratory viruses across periods of low and high prevalence.

Results

Of 50,022 RPPs performed for 34,610 patients, 44% were positive for at least one target, and 67% of these were from children. The overwhelming majority of co-infections (93%) were seen among children, for whom 21% of positive RPPs had two or more viruses detected, as compared to just 4% in adults. Relative to children for whom RPPs were ordered, children with co-infections were younger (3.0 vs 4.5 years) and more likely to be seen in the ED or outpatient settings than inpatient and ICU settings. In children, most viral co-infections were found at significantly reduced rates relative to that expected from the incidence of each virus, especially those involving SARS-CoV-2 and influenza. SARS-CoV-2 positive children had an 85%, 65% and 58% reduced rate of co-infection with influenza, RSV, and Rhino/enteroviruses, respectively, after compensating for the incidence of infection with each virus (p< 0.001).

Discussion

Our results demonstrate that most respiratory viruses peaked in different months and present in co-infections less than would be expected based on overall rates of infection, suggesting a viral exclusionary effect between most seasonal respiratory viruses, including SARS-CoV-2, influenza and RSV. We also demonstrate the significant burden of respiratory viral co-infections among children. Further work is necessary to understand what predisposes certain patients for viral co-infection despite this exclusionary effect.

Multicenter Evaluation of the BIOFIRE Blood Culture Identification 2 Panel for Detection of Bacteria, Yeasts, and Antimicrobial Resistance Genes in Positive Blood Culture Samples

Diagnostic tools that can rapidly identify and characterize microbes growing in blood cultures are important components of clinical microbiology practice because they help to provide timely information that can be used to optimize patient management. This publication describes the bioMérieux BIOFIRE Blood Culture Identification 2 (BCID2) Panel clinical study that was submitted to the U.S. Food & Drug Administration. Results obtained with the BIOFIRE BCID2 Panel were compared to standard-of-care (SoC) results, sequencing results, PCR results, and reference laboratory antimicrobial susceptibility testing results to evaluate the accuracy of its performance. Results for 1,093 retrospectively and prospectively collected positive blood culture samples were initially enrolled, and 1,074 samples met the study criteria and were included in the final analyses. The BIOFIRE BCID2 Panel demonstrated an overall sensitivity of 98.9% (1,712/1,731) and an overall specificity of 99.6% (33,592/33,711) for Gram-positive bacteria, Gram-negative bacteria and yeast targets which the panel is designed to detect. One hundred eighteen off-panel organisms, which the BIOFIRE BCID2 Panel is not designed to detect, were identified by SoC in 10.6% (114/1,074) of samples. The BIOFIRE BCID2 Panel also demonstrated an overall positive percent agreement (PPA) of 97.9% (325/332) and an overall negative percent agreement (NPA) of 99.9% (2,465/2,767) for antimicrobial resistance determinants which the panel is designed to detect. The presence or absence of resistance markers in Enterobacterales correlated closely with phenotypic susceptibility and resistance. We conclude that the BIOFIRE BCID2 Panel produced accurate results in this clinical trial.

Congenital Tuberculosis After In Vitro Fertilization: A Case for Tuberculosis Screening of Women Evaluated for Infertility

We report a case of multidrug-resistant congenital tuberculosis (TB) in an infant conceived by in vitro fertilization and review 22 additional infant-mother pairs in the literature. Females evaluated for infertility should be screened for TB risk, and those at risk require a TB-specific diagnostic evaluation before receiving assisted reproductive treatment.

A case of novel, rapidly-growing Mycolicibacter kumamotonensis infection in a patient with severe pulmonary disease treated in New York City

INTRODUCTION

Mycolicibacter kumamotonensis is a slowly growing, non-chromogenic non-tuberculous mycobacteria (NTM) that was initially distinguished from the M. terrae complex in 2006. Since then it has been rarely reported as the cause of pulmonary and soft-tissue infections in both immunocompromised and immunocompetent patients.

CASE PRESENTATION

We present a case of severe pulmonary disease due to Mycolicibacter kumamotonensis in a 57-year-old male who was immunocompetent at time of diagnosis, with a history of interstitial lung disease and a prior diagnosis of tuberculosis (TB). After initial treatment for TB in 2017, his condition stabilized until a recurrence in September 2021, leading to an evaluation for lung transplant in the setting of pulmonary fibrosis and emphysema which led to the identification of Mycolicibacter kumamotonensis. A lung transplant was completed, and the patient was successfully treated with a combination of Ethambutol, Azithromycin, and Rifabutin.

CONCLUSIONS

This represents the first case reported of M. kumamotonensis in a patient undergoing lung transplant, and the first case with rapid culture growth during identification of the organism (4 days). This report highlights the need for consideration of M. kumamotonensis as a pathogen in humans, with the potential for rapid growth in liquid media, and the importance of early identification to inform empiric therapy.

Partial ORF1ab Gene Target Failure with Omicron BA.2.12.1

Mutations in the genome of SARS-CoV-2 can affect the performance of molecular diagnostic assays. In some cases, such as S-gene target failure, the impact can serve as a unique indicator of a particular SARS-CoV-2 variant and provide a method for rapid detection. Here, we describe partial ORF1ab gene target failure (pOGTF) on the cobas SARS-CoV-2 assays, defined by a ≥2-thermocycle delay in detection of the ORF1ab gene compared to that of the E-gene. We demonstrate that pOGTF is 98.6% sensitive and 99.9% specific for SARS-CoV-2 lineage BA.2.12.1, an emerging variant in the United States with spike L452Q and S704L mutations that may affect transmission, infectivity, and/or immune evasion. Increasing rates of pOGTF closely mirrored rates of BA.2.12.1 sequences uploaded to public databases, and, importantly, increasing local rates of pOGTF also mirrored increasing overall test positivity. Use of pOGTF as a proxy for BA.2.12.1 provides faster tracking of the variant than whole-genome sequencing and can benefit laboratories without sequencing capabilities.

Multicenter Evaluation of the BioFire Respiratory Panel 2.1 (RP2.1) for Detection of SARS-CoV-2 in Nasopharyngeal Swab Samples

As the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) begins to overlap with the traditional respiratory season in the Northern Hemisphere, simultaneous testing for SARS-CoV-2 and the other common causes of respiratory infections is imperative. This has led to the development of multiplex respiratory assays that include SARS-CoV-2 as a target. One such assay is the BioFire respiratory panel 2.1 (RP2.1), which is an expansion of the original BioFire FilmArray respiratory panel 2 (RP2) to include SARS-CoV-2. In this multicenter evaluation, we assessed the performance characteristics of the BioFire RP2.1 for the detection of SARS-CoV-2. One or more targets on the panel were detected in 19.3% (101/524) of specimens tested, with SARS-CoV-2 detected in 12.6% (66/524) of specimens. Human rhinovirus/enterovirus was also detected in 32.7% (33/101) and adenovirus in 3.0% (3/101) of positive specimens, with one dual positive for both SARS-CoV-2 and adenovirus being detected. A further breakdown of pathogens by age revealed a 4-fold predominance of human rhinovirus/enterovirus in subjects 0 to 18 years of age, whereas in all other age groups, SARS-CoV-2 was clearly the predominant pathogen. Overall, SARS-CoV-2 results obtained from the BioFire RP2.1 were highly concordant with the composite result, exhibiting 98.4% (61/62) positive percent agreement (95% confidence interval [CI], 91.4 to 99.7%) and 98.9% (457/462) negative percent agreement (95% CI, 97.5 to 99.5%) with further analysis of discordant results suggesting that the concentration of SARS-CoV-2 in the specimens was near the limit of detection (LoD) for both the BioFire RP2.1 and the comparator assays. Overall, the BioFire RP2.1 exhibited excellent performance in the detection of SARS-CoV-2.

Partial ORF1ab Gene Target Failure with Omicron BA.2.12.1

Mutations in the viral genome of SARS-CoV-2 can impact the performance of molecular diagnostic assays. In some cases, such as S gene target failure, the impact can serve as a unique indicator of a particular SARS-CoV-2 variant and provide a method for rapid detection. Here we describe partial ORF1ab gene target failure (pOGTF) on the cobas ^® SARS-CoV-2 assays, defined by a ≥2 thermocycles delay in detection of the ORF1ab gene compared to the E gene. We demonstrate that pOGTF is 97% sensitive and 99% specific for SARS-CoV-2 lineage BA.2.12.1, an emerging variant in the United States with spike L452Q and S704L mutations that may impact transmission, infectivity, and/or immune evasion. Increasing rates of pOGTF closely mirrored rates of BA.2.12.1 sequences uploaded to public databases, and, importantly increasing local rates of pOGTF also mirrored increasing overall test positivity. Use of pOGTF as a proxy for BA.2.12.1 provides faster tracking of the variant than whole-genome sequencing and can benefit laboratories without sequencing capabilities.

Development of the RealTime SARS-CoV-2 quantitative Laboratory Developed Test and correlation with viral culture as a measure of infectivity

While diagnosis of COVID-19 relies on qualitative molecular testing for the absence or presence of SARS-CoV-2 RNA, quantitative viral load determination for SARS-CoV-2 has many potential applications in antiviral therapy and vaccine trials as well as implications for public health and quarantine guidance. To date, no quantitative SARS-CoV-2 viral load tests have been authorized for clinical use by the FDA. In this study, we modified the FDA emergency use authorized qualitative RealTime SARS-CoV-2 assay into a quantitative SARS-CoV-2 Laboratory Developed Test (LDT) using newly developed Abbott SARS-CoV-2 calibration standards. Both analytical and clinical performance of this SARS-CoV-2 quantitative LDT was evaluated using nasopharyngeal swabs (NPS). We further assessed the correlation between Ct and the ability to culture virus on Vero CCL81 cells. The SARS-CoV-2 quantitative LDT demonstrated high linearity with R2 value of 0.992, high inter- and intra-assay reproducibility across the dynamic range (SDs ± 0.08-0.14 log10 copies/mL for inter-assay reproducibility and ± 0.09 to 0.19 log10 copies/mL for intra-assay reproducibility). Lower limit of detection was determined as 1.90 log10 copies/mL. The highest Ct at which CPE was detected ranged between 28.21-28.49, corresponding to approximately 4.2 log10 copies/mL. Quantitative tests, validated against viral culture capacity, may allow more accurate identification of individuals with and without infectious viral shedding from the respiratory tract.

Evaluating the Effect of a Modified Sample Preparation on SARS-CoV-2 Detection in a Cartridge-Based Platform

Introduction

The ePlex^® SARS-CoV-2 emergency use authorization (EUA) test is a cartridge-based assay for the detection of SARS-CoV-2 in nasopharyngeal specimens. Since performance data has been previously published on this platform, the manufacturer has modified the workflow design in order to improve assay performance. Evaluation of the new workflow, which eliminated the sample delivery device (SDD), led to a dramatic improvement of assay performance while saving time and making cartridge loading more convenient.

Methods

145 confirmed positive nasopharyngeal swab specimens were used to evaluate the assay analytical sensitivity, accuracy, and overall time-saving for the 2 workflows that is with and without the use of SDD on the ePlex SARS-CoV-2 test.

Results

Elimination of the SDD step led to a dramatic increase in accuracy and the overall limit of detection when using 145 previously defined and valid SARS-CoV-2 positive specimens with relatively low, medium, and high cycle thresholds (C_T). This simple workflow change led to an overall detection from 94/145 (64.8%) to 131/145 (90.3%), with an additional 37 specimens being detected. C_T value ranges revealed that 90% of the specimens in the 33 ≤ C_T < 35.3 C_T range were detected, whereas with the SDD workflow, only 30% of positive specimens were detected in this same range. Hands-on time for each specimen also improved and showed overall time savings.

Conclusion

The simple workflow modification eliminating the SDD led to an overall improvement in the detection of positive specimens and also simplified workflow and reduced hands-on time.

Herpes Simplex Virus-1 and -2 Rapid Detection in Whole Blood

BACKGROUND

Disseminated herpes simplex virus (HSV) infection has high morbidity and mortality, particularly in neonates, and requires rapid diagnosis for proper treatment. Currently, there are no US FDA-approved assays available to perform HSV testing on blood.

OBJECTIVES

Our goal was to evaluate the analytical sensitivity and clinical performance of an available sample-to-answer real-time polymerase chain reaction (PCR) platform used as a laboratory-developed test (LDT) for the detection of HSV-1 and -2 in whole blood (WB).

METHODS

A clinical comparison study comparing a real-time PCR reference assay to a LDT based on the DiaSorin Simplexa Direct assay kit was performed. Analytical sensitivity studies comparing WB to the FDA-approved specimen type, cerebrospinal fluid (CSF), were also conducted with contrived quantified HSV-1 and -2 samples in WB and CSF matrix.

RESULTS

In total, 102 samples were tested using the LDT and reference assay for the clinical correlation study, with 91 negative and 10 positive results for HSV-1 (n = 7) and HSV-2 (n = 3), exhibiting 100% concordance with comparator results. The overall limit of detection (LoD) for HSV-1 and HSV-2 in WB was comparable to that seen in CSF, with the calculated 95% LoD for blood being 1489 ± 16 copies/ml for HSV-1 and 1187 ± 18 copies/ml for HSV-2 and for CSF being 1168 ± 17 copies/ml for HSV-1 and 953 ± 21 copies/ml for HSV-2.

CONCLUSIONS

The performance of the LDT for detection of HSV-1 and HSV-2 in WB specimens is adequate for clinical use. The LoD for HSV-1 and HSV-2 is comparable to that in CSF, the FDA-approved specimen type.

Rapid Emergence of SARS-CoV-2 in the Greater New York Metropolitan Area: Geolocation, Demographics, Positivity Rates, and Hospitalization for 46 793 Persons Tested by Northwell Health

BACKGROUND

In March 2020, the greater New York metropolitan area became an epicenter for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The initial evolution of case incidence has not been well characterized.

METHODS

Northwell Health Laboratories tested 46 793 persons for SARS-CoV-2 from 4 March through 10 April. The primary outcome measure was a positive reverse transcription-polymerase chain reaction test for SARS-CoV-2. The secondary outcomes included patient age, sex, and race, if stated; dates the specimen was obtained and the test result; clinical practice site sources; geolocation of patient residence; and hospitalization.

RESULTS

From 8 March through 10 April, a total of 26 735 of 46 793 persons (57.1%) tested positive for SARS-CoV-2. Males of each race were disproportionally more affected than females above age 25, with a progressive male predominance as age increased. Of the positive persons, 7292 were hospitalized directly upon presentation; an additional 882 persons tested positive in an ambulatory setting before subsequent hospitalization, a median of 4.8 days later. Total hospitalization rate was thus 8174 persons (30.6% of positive persons). There was a broad range (>10-fold) in the cumulative number of positive cases across individual zip codes following documented first caseincidence. Test positivity was greater for persons living in zip codes with lower annual household income.

CONCLUSIONS

Our data reveal that SARS-CoV-2 incidence emerged rapidly and almost simultaneously across a broad demographic population in the region. These findings support the premise that SARS-CoV-2 infection was widely distributed prior to virus testing availability.

Exophiala Dermatitidis Isolated From Blood In Patient With Steroid Use

Casestudy

Exophiala dermatitidis is a dematiaceous mold that is associated with subcutaneous, central nervous system and pulmonary infections; osteomyelitis; and disseminated disease. Isolation of E. dermatitidis from patients with mild symptoms may be difficult to interpret whether is a contaminant or asymptomatic patient with serious infection. However, it is important to diagnose asymptomatic patients early in the stage because of up to 25% mortality rate.

Results

77-year-old male with history of chronic obstructive pulmonary disease presented to his pulmonologist with cough. He was started on azithromycin and steroids. His cough worsened and he was transitioned to levofloxacin with continuation of steroid treatment. In addition, he developed fatigue, weakness, poor appetite, chills and nights sweat along with some urinary complaints. His chest X-ray showed infiltrates and he was diagnosed with left lower lung pneumonia and urinary tract infection and was treated with doxycycline and ciprofloxacin. Blood cultures were drawn. Additional past medical history was not significant.

Blood culture became positive on day 4 of incubation. Gram stain showed yeast-like cells, but the blood culture multiplex PCR was negative. Serum cryptococcus antigen was negative. Three days later, a dark shiny olive-colored colony with dark obverse side was isolated. It grew at 42 C. Microscopic examination revealed hyaline and pigmented hyphae with brown conidia. It was identified as Exophiala dermatitidis and confirmed by the state public health laboratory. Blood cultures drawn after hospital admission remained negative. Patient’s symptoms improved with antibiotic treatment. Therefore the clinicians believed that the E. dermatitidis was a probable contaminant and patient was discharged with follow-up. During the follow-up process he developed respiratory infection with Coronavirus (HKU1, NL63, 229E, OC43). Follow-up continues.

Conclusion

Blood cultures are not sensitive for mold infection especially for an uncommon contaminant like E. dermatitidis, it may be difficult to decide whether a positive culture is a real result or not. Fungal antigen tests such as beta-D-glucan test may be helpful in distinguishing between invasive infection and contaminant. Additionally, we believe that in our case, steroid use could have caused a temporary immunosuppression and led to Exophiala dermatitidis infection.

Development of a New Multiplex Real-Time RT-PCR Assay for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Detection

This research describes the development of a new multiplex real-time RT-PCR test for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with primers designed to amplify a 108 bp target on the spike surface glycoprotein (S gene) and a hydrolysis TaqMan probe designed to specifically detect SARS-CoV-2. The limit of detection (LOD) and clinical performance of this new assay were evaluated. A LOD study with inactivated virus exhibited performance equal to the modified CDC assay, with a final LOD of 1301 ± 13 genome equivalents/mL for the Northwell Health Laboratories laboratory-developed test (NWHL LDT) versus 1249 ± 14 genome equivalents/mL for the modified CDC assay. In addition, a clinical evaluation with 270 nasopharyngeal swab specimens exhibited 98.5% positive percent agreement and 99.3% negative percent agreement compared with the modified CDC assay. The NWHL LDT multiplex design allows testing of 91 patients per plate, versus a maximum of 29 patients per plate on the modified CDC assay, providing the benefit of testing significantly more patients per run and saving reagents, during a time when both of these parameters are critical. The results show that the NWHL LDT multiplex assay performs as well as the modified CDC assay but is more efficient and cost-effective and can be used as a diagnostic assay and for epidemiologic surveillance and clinical management of SARS-CoV-2.

3D Printed Alternative to the Standard Synthetic Flocked Nasopharyngeal Swabs Used for COVID-19 testing

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, can be detected in respiratory samples by Real-time Reverse Transcriptase (RT)-PCR or other molecular methods. Accessibility of diagnostic testing for COVID-19 has been limited by intermittent shortages of supplies required for testing, including flocked nasopharyngeal (FLNP) swabs.

Methods

We developed a 3D-printed nasopharyngeal (3DP) swab as a replacement of the FLNP swab. The performance of 3DP and FLNP swabs were compared in a clinical trial of symptomatic patients at three clinical sites (n=291) using three SARS-CoV-2 EUA tests: a modified version of the CDC Real-time Reverse Transcriptase (RT)-PCR Diagnostic Panel and two commercial automated formats, Roche Cobas and NeuMoDx.

Results

The cycle threshold (C(t)) values from the gene targets and the RNase P gene control in the CDC assay showed no significant differences between swabs for both gene targets (p=0.152 and p=0.092), with the RNase P target performing significantly better in the 3DP swabs (p & 0.001). The C(t) values showed no significant differences between swabs for both viral gene targets in the Roche cobas assay (p=0.05 and p=0.05) as well as the NeuMoDx assay (p=0.401 and p=0.484). The overall clinical correlation of COVID-19 diagnosis between all methods was 95.88% (Kappa 0.901).

Conclusions

3DP swabs were equivalent to standard FLNP in three testing platforms for SARS-CoV-2. Given the need for widespread testing, 3DP swabs printed on-site are an alternate to FLNP that can rapidly scale in response to acute needs when supply chain disruptions affect availability of collection kits.

Analytical and Clinical Comparison of Three Nucleic Acid Amplification Tests for SARS-CoV-2 Detection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified in December 2019 and has quickly become a worldwide pandemic. In response, many diagnostic manufacturers have developed molecular assays for SARS-CoV-2 under the Food and Drug Administration (FDA) Emergency Use Authorization (EUA) pathway. This study compared three of these assays, the Hologic Panther Fusion SARS-CoV-2 assay (Fusion), the Hologic Aptima SARS-CoV-2 assay (Aptima), and the BioFire Defense COVID-19 test (BioFire), to determine analytical and clinical performance as well as workflow. All three assays showed similar limits of detection (LODs) using inactivated virus, with 100% detection, ranging from 500 to 1,000 genome equivalents/ml, whereas use of a quantified RNA transcript standard showed the same trend but had values ranging from 62.5 to 125 copies/ml, confirming variability in absolute quantification of reference standards. The clinical correlation found that the Fusion and BioFire assays had a positive percent agreement (PPA) of 98.7%, followed by the Aptima assay at 94.7%, compared to the consensus result. All three assays exhibited 100% negative percent agreement (NPA). Analysis of discordant results revealed that all four samples missed by the Aptima assay had cycle threshold (C_t ) values of >37 by the Fusion assay. In conclusion, while all three assays showed similar relative LODs, we showed differences in absolute LODs depending on which standard was employed. In addition, the Fusion and BioFire assays showed better clinical performance, while the Aptima assay showed a modest decrease in overall PPA. These findings should be kept in mind when making platform testing decisions.

651. Multi-Center Evaluation of the BioFire® FilmArray® Blood Culture Identification 2 Panel for the Detection of Microorganisms and Resistance Markers in Positive Blood Cultures

Background

The BioFire® FilmArray® Blood Culture Identification 2 (BCID2) Panel is a diagnostic test that provides results for 26 bacterial, 7 fungal pathogens and 10 antimicrobial resistance (AMR) genes from positive blood culture (PBC) specimens in about an hour. The BCID2 Panel builds upon the existing BCID Panel with several additional assays that include Candida auris and an expanded AMR gene menu that provides methicillin-resistant Staphylococcus aureus (MRSA) results plus detection for mcr-1, carbapenem resistance, and ESBL. Here, we summarize studies conducted to establish clinical performance using an Investigational Use Only version of the BCID2 Panel.

Methods

Three studies were performed. The first involves prospective collection and testing of an expected ~1,000 residual PBCs at 7 US and 2 EU sites, which began in October 2018 and will conclude in June 2019. BCID2 Panel performance is compared with reference methods of microbial culture as well as PCR/sequencing for AMR genes. In addition, BCID2 Panel MRSA results are compared with the FDA-cleared Xpert MRSA/SA BC system (Cepheid, Inc). Relevant bacterial isolates recovered from PBCs are also evaluated by various phenotypic antimicrobial susceptibility testing (AST) methods. The prospective evaluation is supplemented with a second study that involves testing of ~300 pre-selected, archived PBCs containing rare organisms. The third study includes over 500 seeded blood cultures containing very rare organisms with an evaluation of co-spiked samples.

Results

With over 1,200 samples tested to date (out of an anticipated 1,800 total), the BCID2 Panel has demonstrated an overall sensitivity of >98% and specificity of >99% for identification of microorganisms compared with culture. Concordance between the BCID2 Panel and the Xpert MRSA/SA BC test is >99% for identification of MRSA. Evaluation of BCID2 Panel AMR gene detection relative to AST and PCR is ongoing.

Conclusion

The FilmArray® BCID2 Panel appears to be a sensitive, specific, and robust test for rapid detection of microorganisms and MRSA in PBCs. With the use of this comprehensive test, improved antimicrobial stewardship is anticipated.

Disclosures

All authors: No reported disclosures

Comparison of the Alere i and BD Veritor Assays for the Rapid Detection of Influenza A and B Viruses

BACKGROUND

The use of point-of care testing (POCT) in patient management decisions is becoming increasingly common. Our goal was to evaluate the diagnostic performance of 2 commercially available rapid POCT devices for influenza viruses A and B: the Alere™ i Instrument (Alere, Scarborough) and the BD Veritor™ System (BD Diagnostics).

METHODS

Paired nasopharyngeal swabs were collected from patients (18-71 years) presenting with influenza-like symptoms at 3 outpatient clinics. A total of 65 samples were obtained. The Alere i and BD Veritor were performed according to the manufacturers' instructions. Discordant results were resolved using real-time reverse transcription PCR (RT-PCR).

RESULTS

In a head-to-head comparison involving symptomatic adult patients visiting outpatient clinics during the 2014-2015 and 2015-2016 influenza seasons, the Alere i and BD Veritor had 90.63% agreement in the detection of influenza A virus and a statistically significant observed κ coefficient of 0.754 (P <0.0001). Discordant results between the Alere i and BD Veritor were further investigated using RT-PCR, showing that the BD Veritor missed 5 positive influenza A virus results (false negatives) and detected 1 false positive, while the Alere i results agreed with all RT-PCR results. There were no discordant results between the Alere i and BD Veritor in the detection of influenza B virus.

CONCLUSIONS

Our data suggest that the Alere i has higher sensitivity and specificity than the BD Veritor in the detection of influenza A virus. Both assays showed equal performance in the detection of influenza B virus.

Giant cell myocarditis: a rare cardiovascular manifestation in a patient with systemic lupus erythematosus

Giant cell myocarditis (GCM) is a rare form of myocarditis with a median survival of less than one year. It has been reported to occur in patients with various underlying autoimmune diseases; however, no cases of GCM have been described in patients with clear evidence of underlying systemic lupus erythematosus (SLE). The presentation of GCM may mimic that of lupus myocarditis, including an initial response to immunosuppression. Despite initial clinical similarities, lupus myocarditis and GCM are histologically distinct entities with dramatic differences in prognosis. We report herein a patient with a longstanding history of SLE, who presented acutely with myocarditis, responded well to initial immunosuppression and then subsequently died of progressive heart failure that was found to be due to GCM. Endomyocardial biopsy can help define diagnosis and prognosis of lupus patients presenting with myocarditis, and early referral for cardiac transplantation should be considered in patients diagnosed with GCM.

Identifying type 1 diabetes candidate genes by DNA microarray analysis of islet-specific CD4 + T cells

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease resulting from the destruction of insulin-producing pancreatic beta cells and is fatal unless treated with insulin. During the last four decades, multiple insulin-dependent diabetes (Idd) susceptibility/resistance loci that regulate T1D development have been identified in humans and non-obese diabetic (NOD) mice, an established animal model for T1D. However, the exact mechanisms by which these loci confer diabetes risk and the identity of the causative genes remain largely elusive. To identify genes and molecular mechanisms that control the function of diabetogenic T cells, we conducted DNA microarray analysis in islet-specific CD4 + T cells from BDC2.5 TCR transgenic NOD mice that contain the Idd9 locus from T1D-susceptible NOD mice or T1D-resistant C57BL/10 mice. Here we describe in detail the contents and analyses for these gene expression data associated with our previous study [1]. Gene expression data are available at the Gene Expression Omnibus (GEO) repository from the National Center for Biotechnology Information (accession number GSE64674).

Genome-wide transcriptional analyses of islet-specific CD4+ T cells identify Idd9 genes controlling diabetogenic T cell function

Type 1 diabetes (T1D) is a polygenic disease with multiple insulin-dependent diabetes (Idd) loci predisposing humans and NOD mice to disease. NOD.B10 Idd9 congenic mice, in which the NOD Idd9 chromosomal region is replaced by the Idd9 from T1D-resistant C57BL/10 mice, are significantly protected from T1D development. However, the genes and pathways conferring T1D development or protection by Idd9 remain to be fully elucidated. We have developed novel NOD.B10-Idd9 (line 905) congenic mice that predominantly harbor islet-reactive CD4(+) T cells expressing the BDC2.5 TCR (BDC-Idd9.905 mice). To establish functional links between the Idd9 genotype and its phenotype, we used microarray analyses to investigate the gene expression profiles of ex vivo and Ag-activated CD4(+) T cells from these mice and BDC2.5 (BDC) NOD controls. Among the differentially expressed genes, those located within the Idd9 region were greatly enriched in islet-specific CD4(+) T cells. Bioinformatics analyses of differentially expressed genes between BDC-Idd9.905 and BDC CD4(+) T cells identified Eno1, Rbbp4, and Mtor, all of which are encoded by Idd9 and part of gene networks involved in cellular growth and development. As predicted, proliferation and Th1/Th17 responses of islet-specific CD4(+) T cells from BDC-Idd9.905 mice following Ag stimulation in vitro were reduced compared with BDC mice. Furthermore, proliferative responses to endogenous autoantigen and diabetogenic function were impaired in BDC-Idd9.905 CD4(+) T cells. These findings suggest that differential expression of the identified Idd9 genes contributed to Idd9-dependent T1D susceptibility by controlling the diabetogenic function of islet-specific CD4(+) T cells.

The type 1 diabetes resistance locus B10 Idd9.3 mediates impaired B-cell lymphopoiesis and implicates microRNA-34a in diabetes protection

NOD.B10 Idd9.3 mice are congenic for the insulin-dependent diabetes (Idd) Idd9.3 locus, which confers significant type 1 diabetes (T1D) protection and encodes 19 genes, including microRNA (miR)-34a, from T1D-resistant C57BL/10 mice. B cells have been shown to play a critical role in the priming of autoantigen-specific CD4(+) T cells in T1D pathogenesis in non-obese diabetic (NOD) mice. We show that early B-cell development is impaired in NOD.B10 Idd9.3 mice, resulting in the profound reduction of transitional and mature splenic B cells as compared with NOD mice. Molecular analysis revealed that miR-34a expression was significantly higher in B-cell progenitors and marginal zone B cells from NOD.B10 Idd9.3 mice than in NOD mice. Furthermore, miR-34a expression in these cell populations inversely correlated with levels of Foxp1, an essential regulator of B-cell lymphopoiesis, which is directly repressed by miR-34a. In addition, we show that islet-specific CD4(+) T cells proliferated inefficiently when primed by NOD.B10 Idd9.3 B cells in vitro or in response to endogenous autoantigen in NOD.B10 Idd9.3 mice. Thus, Idd9.3-encoded miR-34a is a likely candidate in negatively regulating B-cell lymphopoiesis, which may contribute to inefficient expansion of islet-specific CD4(+) T cells and to T1D protection in NOD.B10 Idd9.3 mice.

Salivary gland anlage tumor in a neonate presenting with respiratory distress: radiographic and pathologic correlation

We present a case of congenital salivary gland anlage tumor (SGAT) of the nasal septum in a 2-week-old infant who had difficulty breathing through her nose since birth. CT and MR imaging demonstrated a circumscribed mass within the nasal cavity that did not communicate with the intracranial compartment. Differential diagnosis and clinical significance of recognizing this rare lesion are reviewed.

The pathology of hibernating myocardium

Myocardial hibernation represents a protective mechanism of muscle preservation in the setting of atherosclerotic coronary artery disease. Long-standing myocardial hypoperfusion leads to diminished myocardial contractility that reverses with improved blood flow after revascularization. The morphologic changes in both animal models and humans are described.

CT of noninfectious granulomatous lung disease

Noninfectious granulomatous diseases of the lung consist of a diverse group of disorders that logically can be subdivided into those with and without associated vasculitis. This article reviews the epidemiologic, clinical, pathologic, and radiologic features of sarcoidosis, hypersensitivity pneumonitis, berylliosis, and the five entities traditionally classified as pulmonary angiitis and granulomatosis.

In vivo imaging of acute cardiac rejection in human patients using (99m)technetium labeled annexin V

Annexin V binds phosphatidylserine moieties on apoptotic cells. This study reports the initial experience at Stanford University Medical Center with 99mTc-labeled annexin V imaging as a noninvasive measure of apoptosis in acute cardiac rejection. Ten cardiac transplant patients had 99mTc Annexin V imaging and endomyocardial biopsy (EMB) performed within 24 h. No complications related to 99mTc annexin V administration occurred. Eight patients had ISHLT grade of acute rejection of 1A or less. Five patients had two or more areas of uptake noted in the right ventricle on imaging studies. Two of these patients had positive biopsies: one patient had grade 2 rejection with two focal uptake areas and another had grade 3A rejection with three foci. An additional five patients had either one or zero hot spot areas and corresponding negative EMBs. 99mTc-annexin V appears to be well tolerated and may identify patients with acute cardiac rejection.

Viral serine proteinase inhibitor (SERP-1) effectively decreases the incidence of graft vasculopathy in heterotopic heart allografts

BACKGROUND

Graft vascular disease (GVD) is the most common cause of late graft failure in solid organ transplantation. Recent studies have shown good efficacy of a novel nontoxic viral-derived serine proteinase inhibitor (SERP-1) in preventing postangioplasty restenosis. The current study was designed to test whether short-term treatment with SERP-1 was effective in reducing the incidence of GVD in a solid organ transplant.

METHODS

Piebald-Virol-Glaxo (PVG) donor hearts were transplanted into August-Copenhagen-Irish (ACI) recipients and observed for 90 days. All recipients (n=60) were treated with microemulsion cyclosporine (CsA) 7.5 mg/kg per gavage from day 0 to day 9 and randomized into 4 groups. SERP-1 was given intravenously. Group I received CsA monotherapy; group II, CsA+SERP-1 1 ng/g (postoperative days 0-9); group III, CsA+SERP-1 10 ng/g (postoperative days 0-9); and group IV, CsA+SERP-1 10 ng/g (postoperative days 0-9, 30, and 60). Graft viability was monitored by palpation, and GVD was assessed by morphometry.

RESULTS

Two animals in group I rejected their allografts on postoperative days 7 and 14, 1 animal in group II rejected the allograft (postoperative day 31), and none in group III and IV rejected the allografts. At 90 days postoperative, 23.8% of all coronary vessels showed evidence of GVD in group I, 18.4% in group II, 12.9% in group III, and 11.8% in group IV. The difference in incidence of GVD was significant between groups I and III (P<0.05) and groups I and IV (P<0.05). Treatment with SERP-1 was well tolerated, and all animals regained weight quickly postsurgery.

CONCLUSIONS

Treatment of allograft recipients with SERP-1 in combination with CsA early after transplantation significantly decreases the incidence of GVD when compared to grafts treated with only CsA. These results demonstrate the clinical potential for this novel serine protease inhibitor to prevent GVD in solid organ transplantation.

Prolonged inhibition of obliterative airway disease in murine tracheal allografts by brief treatment with anti-leukocyte function-associated antigen-1 (CD11a) monoclonal antibody

BACKGROUND

We have previously shown that anti-leukocyte function-associated antigen (LFA)-1 (CD11a) monoclonal antibody (mAb) prevents acute rejection and produces donor-specific unresponsiveness in murine recipients of heterotopic heart allografts. Here, we investigate the ability of this mAb to prevent the development of obliterative airway disease (OAD) in murine recipients of tracheal allografts.

METHODS AND RESULTS

BALB/c tracheae were heterotopically transplanted into C3H mice. OAD developed by day 28 after transplantation and was characterized histologically by a loss of epithelial cell coverage and luminal obliteration of the tracheal allograft with a proliferation of fibrogenic mesenchymal cells, which is a lesion comparable to obliterative bronchiolitis in human lung transplant recipients. Monotherapy with anti-LFA-1 mAb preserved graft epithelium, prevented the development of OAD, and maintained unresponsiveness to donor antigen for more than 42 days after the final mAb administration.

CONCLUSION

These findings suggest the potential for anti-LFA-1 mAb therapy to suppress both acute and chronic rejection in clinical lung transplantation.

Il-18 gene transfer by adenovirus prevents the development of and reverses established allergen-induced airway hyperreactivity

We examined the role of IL-18 in preventing the development of and in reversing established allergen-induced airway inflammation and airway hyperreactivity (AHR), the cardinal features of asthma. IL-18, which potently induces IFN-gamma, was administered into the respiratory tract as cDNA in a replication-deficient adenovirus (Adv). Treatment of OVA-sensitized mice with the IL-18-expressing Adv reduced allergen-specific IL-4 production, airway eosinophilia, and mucus production, increased IFN-gamma production, and prevented the development of AHR. The effects of the IL-18 Adv treatment were dependent on the presence of IFN-gamma and IL-12. Moreover, administration of the IL-18 Adv to mice with established AHR greatly reduced AHR and IL-4 production and increased IFN-gamma production. These results demonstrate that IL-18, when administered by Adv into the respiratory tract, effectively reduces AHR and replaces an established Th2-biased immune response with a Th1-biased response.

40-O-(2-hydroxyethyl)-rapamycin attenuates pulmonary arterial hypertension and neointimal formation in rats

Pneumonectomized rats develop pulmonary hypertension (PH) and pulmonary vascular neointimal formation 4 wk after monocrotaline (MCT) administration. Male Sprague-Dawley rats were injected with MCT (60 mg/kg) on Day 7 after left pneumonectomy. Three groups (n = 5) received 40-O-(2-hydroxyethyl)-rapamycin (RAD, 2.5 mg/kg/d, by gavage): Group PMR(5-35) from Day 5 to Day 35, Group PMR5-14 from Day 5 to Day 14, and Group PMR15-35 from Day 15 to Day 35. By Day 35, rats that received vehicle had higher mean pulmonary arterial pressures (Ppa = 41 +/- 3 mm Hg) (p < 0.001), right ventricular systolic pressures (Prv,s = 45 +/- 2 mm Hg) (p < 0.01), and right ventricle/(left ventricle plus septum) (0.55 +/- 0.05) (p = 0.028) than rats in Groups PMR5-35 (Ppa = 25 +/- 3 mm Hg, Prv,s = 32 +/- 7 mm Hg, RV/LV&S = 0.42 +/- 0.06) and PMR5-14 (Ppa = 29 +/- 4 mm Hg, Prv,s = 30 +/- 5 mm Hg, RV/LV&S = 0.43 +/- 0.07). Pulmonary arterial neointimal formation (quantified by a vascular occlusion score) was more severe in vehicle-treated rats (1.93 +/- 0.03) than in Groups PMR5-14 (1.56 +/- 0.27) and PMR(5-35) (1.57 +/- 0.1) (p < 0.01). RAD attenuates the development of MCT-induced pulmonary arterial hypertension in the pneumonectomized rat.

Triptolide attenuates pulmonary arterial hypertension and neointimal formation in rats

This paper reports the effect of triptolide (a diterpenoid triepoxide) on the development of monocrotaline (MCT)-induced pulmonary hypertension in pneumonectomized rats. Male Sprague- Dawley rats were injected with MCT (60 mg/kg) on Day 7 after left pneumonectomy. Rats received therapy from Day 5 to 35 with triptolide (0.25 mg/kg intraperitoneally, every other day, n = 10), or vehicle (0.1 ml of ethanol/cremophor intraperitoneally, every other day, n = 10). By Day 35, triptolide-treated rats demonstrated lower mean pulmonary arterial pressure (mPAP) than vehicle-treated rats (mPAP 21 +/- 3 versus 42 +/- 5 mm Hg, p < 0.001). Triptolide-treated rats also had significantly less right ventricular hypertrophy (RVH) and pulmonary arterial neointimal formation. In a rescue experiment, rats initiated therapy on Day 21. At Day 35, vehicle-treated rats (n = 4) had higher mPAP (40 +/- 9 mm Hg), greater RVH, and more severe pulmonary arterial neointimal formation than rats that received triptolide (0.25 mg/kg every other day, n = 7, mPAP 30 +/- 4 mm Hg) and rats that received triptolide (0.2 mg/kg daily, n = 7, mPAP 25 +/- 5 mm Hg, p < 0.01). In pneumonectomized rats that receive MCT, triptolide attenuates the development of pulmonary hypertension and RVH, and promotes regression of pulmonary arterial neointimal formation.

Zinc-mediated reduction of apoptosis in cardiac allografts

BACKGROUND

Apoptosis is thought to occur during immune-mediated acute rejection of cardiac allografts. In vitro studies have shown that zinc inhibits the activity of the proapoptotic enzyme caspase-3. We hypothesized that ZnCl(2) would reduce acute cardiac rejection in vivo via the blockade of caspase-3-dependent apoptosis. (99m)Tc-labeled annexin V was used to measure apoptosis in cardiac allografts through nuclear imaging. Annexin V binds to phosphatidylserines, which are externalized to the outer membrane of apoptotic cells.

METHODS AND RESULTS

Twenty-seven PVG rat hearts were transplanted heterotopically into the abdomen of untreated ACI rats as controls (group 1). Fifteen were scanned and euthanized on postoperative day 4, and 12 were assessed for graft survival. Group 2 and 3 rats (n=15 each) received 1 and 5 mg/kg ZnCl(2) BID IP, respectively. Nine of each of these groups were scanned and euthanized on postoperative day 4, and 6 were studied for allograft survival. Group 4 rats (n=3) received isografts. Region-of-interest analysis demonstrated a dose-dependent reduction in (99m)Tc annexin uptake in ZnCl(2)-treated allografts: 2.43+/-0.37% for group 1, 1. 97+/-0.41% for group 2, 1.21+/-0.47% for group 3, and 0.55+/-0.19% for group 4 (ANOVA, P:=0.001). Graft survival times of 6.4+/-1.7, 9. 3+/-3.0, and 11.5+/-3.4 days for groups 1, 2, and 3, respectively, were also observed (ANOVA, P:=0.001). Caspase-3 activity in the allografts showed a 3.7-fold reduction in group 3 animals compared with group 1 animals (P:=0.004).

CONCLUSIONS

Apoptosis that occurs in acute cardiac allograft rejection is reduced with ZnCl(2) in a dose-dependent manner via caspase-3 inhibition.

Tissue characterization of atherosclerotic plaques by intravascular ultrasound radiofrequency signal analysis: an in vitro study of human coronary arteries

BACKGROUND

Conventional gray-scale images of intravascular ultrasound (IVUS) cannot accurately differentiate histologic subtypes of sonolucent coronary plaques with or without a lipid core.

METHODS

We analyzed radiofrequency signals obtained in vitro from 24 regions of interest (ROI) of noncalcified (sonolucent) plaques in 10 atherosclerotic coronary artery specimens pressure-fixed by formalin. Radiofrequency signals were sampled with a 30-MHz IVUS catheter and digitized at 500 MHz in 8-bit resolution. The ROIs were histologically categorized into 12 plaques with a lipid core and 12 plaques without it. Integrated backscatter and statistical parameters of the radiofrequency envelope (mean/SD ratio [MSR], skewness, and kurtosis) within the ROI were calculated offline, and their ability to detect a lipid core was compared with visual analysis of the IVUS video images. In the group with lipid cores, percent area of a lipid core in each ROI was measured in a digitized histologic image by a computerized planimeter.

RESULTS

Sensitivity and specificity of MSR, skewness, and kurtosis for lipid core detection were substantially greater than visual video image analysis (83.3% and 91.7%, 100% and 91.7%, 100% and 91.7% vs 53.3% and 71.7%). Furthermore, the parameters of integrated backscatter, MSR, skewness, and kurtosis were significantly correlated to percent of core area (r = -0.64, -0.73, 0.78, and 0.63, respectively; P<.05).

CONCLUSIONS

Compared with IVUS video images, the parameters of radiofrequency signal analysis may be used to aid in more accurate detection and quantitative evaluation of a lipid core, which is one of the major factors of a vulnerable coronary plaque.

Sirolimus (rapamycin) halts and reverses progression of allograft vascular disease in non-human primates

BACKGROUND

Current immunosuppressive protocols fail to prevent chronic rejection often manifested as graft vascular disease (GVD) in solid organ transplant recipients. Several new immunosuppressants including sirolimus, a dual function growth factor antagonist, have been discovered, but studies of drug efficacy have been hampered by the lack of a model of GVD in primates, as a prelude to clinical trials. As described earlier, we have developed a novel non-human primate model of GVD where progression of GVD is quantified by intravascular ultrasound (IVUS).

METHODS

Twelve cynomolgus monkeys underwent aortic transplantation from blood group compatible but mixed lymphocyte reaction-mismatched donors. To allow the development of GVD in the allograft, no treatment was administered for the first 6 weeks. Six monkeys were treated orally with sirolimus from day 45 after transplantation to day 105.

RESULTS

Progression of GVD measured as change in intimal area from day 42 to 105 was halted in sirolimus-treated monkeys compared to untreated monkeys (P<0.001, general linear model). On day 105, the intimal area +/- SEM was 3.7+/-1.0 and 6.4+/-0.5 mm2, respectively (P<0.05, t test). The magnitude of allograft intimal area on day 105 correlated inversely with sirolimus trough levels (R2=0.67, P<0.05). Regression of the intimal area was seen in four of six sirolimus-treated monkeys, which was significantly different from the untreated monkeys (P<0.05).

CONCLUSIONS

Our results in the first non-human primate model of GVD showed that treatment with sirolimus not only halted the progression of preexisting GVD but also was associated with partial regression. Sirolimus trough blood levels were correlated with efficacy. Therefore, sirolimus has the potential to control clinical chronic allograft rejection.

Epithelial re-growth is associated with inhibition of obliterative airway disease in orthotopic tracheal allografts in non-immunosuppressed rats

BACKGROUND

Because epithelial cells are targets of alloimmune injury leading ultimately to airway obliteration, we tested whether epithelial re-growth could prevent obliterative airway disease (OAD) in orthotopic tracheal allografts.

METHODS

Brown Norway tracheal segments were orthotopically transplanted into nonimmunosuppressed Lewis rats. Allografts were removed on days 2-10 (n=13), 30 (n=4), and 60 (n=5) for histology, computerized morphometry (obliteration), and immunohistochemical detection of mononuclear cells, smooth muscle alpha-actin, and tissue phenotype. Normal tracheas, host tracheas, and heterotopically transplanted allografts served as controls.

RESULTS

Orthotopic allografts removed on days 2-10 exhibited epithelial damage and re-growth and mononuclear cell infiltration. On days 30 and 60, partially ciliated cuboidal or attenuated epithelium completely covered the lumen. Although mononuclear cells declined, numerous T cells with a high CD4/CD8 ratio were found in the epithelium till day 60. Orthotopic allograft epithelium expressed donor phenotype on day 7, but recipient phenotype on days 30 and 60. Despite subepithelial alpha-actin positive myofibroblast proliferation, obliteration did not progress from day 7 to 30 and 60 (35, 30, and 33%, respectively). Although more than in normal or host tracheas, the obliteration in orthotopic allografts on days 30 and 60 was significantly less (P<0.001) than in heterotopic allografts.

CONCLUSIONS

We describe, for the first time, longterm patency of fully histoincompatible orthotopic tracheal allografts in nonimmunosuppressed rats. Despite acute alloimmune injury and induction of myofibroblast proliferation, epithelial re-growth from the host limited the progression of OAD, thus emphasizing the role of epithelium in the control of airway obliteration.

Giant cell myocarditis as a manifestation of drug hypersensitivity

Adverse drug effects on the myocardium are often classified into toxic and hypersensitivity forms of myocarditis, each with distinct histologic findings. In contrast, giant cell myocarditis (GCM) is generally not associated with adverse drug reactions and has unique histopathologic features. We report four cases of adverse drug reactions in which the histologic findings were characteristic of GCM. The clinical recognition that GCM may be a manifestation of an adverse drug reaction is important, since the prognosis and treatment of this entity may be different from that of other forms of myocarditis.

Survival outcomes of patients with giant cell myocarditis bridged by ventricular assist devices

Giant cell myocarditis is a highly lethal disorder characterized by rapidly progressive congestive heart failure. The aim of this study was to describe the clinical course of patients with giant cell myocarditis who received a ventricular assist device. Patients with giant cell myocarditis were identified from the Multicenter Giant cell Myocarditis Registry. Bridging to cardiac transplantation in the giant cell myocarditis patients who received a ventricular assist device was compared with bridging in the general population of heart failure patients, as reported in the literature. Median posttransplantation survival for patients with giant cell myocarditis who received and did not receive ventricular assist devices was calculated by the Kaplan-Meier method and compared with use of the log-rank test. Nine patients with giant cell myocarditis who received ventricular assist devices were identified. Seven patients survived to transplantation, four were alive 30 days posttransplantation, and two survived to 1 year. The rate of successful bridging to transplantation in seven of nine patients (78%) is similar to that reported for other ventricular assist device recipients. Posttransplantation survival of 57% (4 of 7) at 30 days and 29% (2 of 7) at 1 year was significantly lower compared with 93% 1-year survival of the 30 patients with giant cell myocarditis who did not receive ventricular assist devices before transplantation (p<0.001). Ventricular assist devices can be an effective bridge to transplantation for patients with heart failure caused by giant cell myocarditis. Although their posttransplantation survival was poor in our series, a few patients had long-term survival.

Tissue distribution and clinical monitoring of the novel macrolide immunosuppressant SDZ-RAD and its metabolites in monkey lung transplant recipients: interaction with cyclosporine

We report the tissue distribution and clinical monitoring of the novel macrolide immunosuppressant SDZ-RAD ¿40-O-(2-hydroxyethyl)-rapamycin and its metabolites in monkey lung transplant recipients as well as its interaction with cyclosporine as the Neoral formulation. After left unilateral lung transplantation, cynomolgus monkeys received by oral administration either 1) 1.5 mg/kg/day SDZ-RAD (n = 4); 2) 100 mg/kg/day cyclosporine (n = 4); 3) 0.3 mg/kg/day SDZ-RAD + 100 mg/kg/day cyclosporine (n = 6); 4) 1.5 mg/kg/day SDZ-RAD + 50 mg/kg/day cyclosporine (n = 5); or 5) SDZ-RAD and cyclosporine doses adjusted according to trough blood concentration measurements (n = 6). At the end of the observation period (usually 29 days after transplantation), and 24 h after the last doses, tissue samples were collected and analyzed with HPLC/mass spectrometry. Gall bladder, pancreas, the transplant lung, cerebellum, kidneys, and spleen had the highest SDZ-RAD concentrations. Coadministration of cyclosporine increased SDZ-RAD concentrations in most tissues as well as tissue-to-blood distribution coefficients. In contrast, SDZ-RAD had only a small effect on cyclosporine blood and tissue concentrations. Rejection in lung grafts in monkeys treated with either of the cyclosporine/SDZ-RAD combinations was significantly less than in the monotherapy groups (P <.002). Histological rejection scores were inversely correlated with SDZ-RAD concentrations in blood (r = -0. 68; P <.001; n = 24), lymph nodes (P = -0.58; P <.003; n = 24), thymus (r = -0.63; P <.001; n = 23) and transplant lung tissue (r = -0.58; P <.003; n = 24). We conclude that, in addition to the synergistic pharmacodynamic interaction, a pharmacokinetic interaction resulting in higher SDZ-RAD tissue concentrations contributed to the significantly better immunosuppressive efficacy when both drugs were combined compared with monotherapy.

Immunosuppressive therapies for the prevention and treatment of obliterative airway disease in heterotopic rat trachea allografts

BACKGROUND

Obliterative bronchiolitis remains a major long-term complication after lung transplantation. Using a reproducible model of heterotopically transplanted rat tracheas, this study examined the role of several novel immunosuppresive compounds to prevent and reverse obliterative airway disease in these animals.

METHODS

Brown Norway rat trachea were transplanted into the greater omentum of Lewis (allografts) or Brown Norway (isografts) animals. Recipient animals were treated with rapamycin, cyclosporine, 15-deoxyspergulin, mycophenolate mofetil, or leflunomide from day 0, 7, or 14 until day of graft removal, either day 28 or 50. Trachea segments were evaluated for degree of lumenal occlusion, as well as percent and type of lumen epithelial cell coverage.

RESULTS

All untreated allografted tracheas obliterated completely, although isografts appeared patent with normal respiratory epithelium when they were removed. Leflunomide, rapamycin, and cyclosporine effectively prevented obliteration when treatment was initiated at day 0, with rapamycin showing continued efficacy when initiated as late as day 7. 15-deoxyspergulin and mycophenolate mofetil failed to consistently inhibit obliteration with any treatment schedule. An inverse correlation was found between epithelial coverage and degree of obliteration, and was especially pronounced in grafts from cyclosporine-treated animals.

CONCLUSIONS

Immunosuppressive drug therapy will inhibit airway obliteration, but efficacy sharply diminishes if initiation of treatment is delayed. Efficacy also varies among immunosuppressive compounds, and results indicate those drugs that enable epithelial regrowth most effectively inhibit airway graft obliteration.

Influenza pneumonia in a paediatric lung transplant recipient

Although a common cause of morbidity and mortality in the general population, influenza infections are uncommon in lung transplant recipients and, to date, have only been associated with transient declines in pulmonary function and a relatively benign clinical course. This paper describes severe influenza pneumonia in a 13-year-old paediatric lung transplant recipient (5 months after double lung transplantation). Influenza pneumonia was diagnosed by direct fluorescent antibody testing and viral culture of bronchoalveolar lavage fluid. The patient required mechanical ventilation for 2 days due to respiratory failure and fatigue. Since his recovery from this pneumonia, he has developed obliterative bronchiolitis and currently awaits re-transplantation.

Dendritic cells and macrophages in lung allografts: A role in chronic rejection?

Antigen presentation by lung macrophages/dendritic cells (DC) is thought to be important in obliterative bronchiolitis/bronchiolitis obliterans syndrome (OB/BOS), which severely limits survival post-lung transplantation. However, a recent study found minimal numbers of DC in lung allografts. We looked at numbers and phenotype of macrophages/DC in lung allografts using endobronchial biopsy (EBB) and transbronchial biopsy (TBB) from 22 lung transplant patients. Biopsies were stained with monoclonal markers of DC (CD1a, RFD1, and major histocompatibility complex [MHC] Class II), and "suppressor macrophages" (RFD1 and RFD7). Dendritic cells were also stained for the costimulatory molecules CD80 and CD86. Significantly greater numbers of DC/high-power field (HPF) were seen in biopsies when we defined DC using dendritic morphology and Class II MHC expression instead of CD1a expression. Dendritic cell numbers were significantly higher in eight patients with OB/BOS compared with 14 stable patients. Fifty percent of DC expressed CD86 and 20% expressed CD80. There was no difference in CD80 or CD86 expression between OB/BOS patients and stable patients. There was no correlation between DC numbers and presence or absence of acute rejection (AR), and/or cytomegalovirus (CMV) pneumonitis on current or prior biopsies. There were significantly more MHC Class II DC in EBB compared with TBB. We found minimal staining for lung macrophages capable of suppressing T-cell inflammation. We conclude that studies of lung allografts may underestimate DC numbers if relying on CD1a as the sole marker of DC. DC are increased in patients with OB/BOS compared with stable patients. EBB may be more important than TBB in looking for inflammatory changes of OB. DC expressing costimulatory molecules are present in lung allografts, and costimulatory pathway blockade may be useful in human lung allografts. Also, the absence of "suppressor" macrophages may increase susceptibility of human lung allografts to the rejection process.

Radionuclide imaging of acute lung transplant rejection with annexin V

STUDY OBJECTIVES

Early detection and treatment of lung transplant rejection is critical for preservation of pulmonary graft function. Damage to pulmonary allografts is mediated by apoptotic cell death induced by the alloreactive T lymphocytes that infiltrate lung grafts. Previous studies demonstrate that acute cardiac allograft rejection can be visualized using radiolabeled annexin V. This study was done to determine whether this technique could visualize acute rejection in a rodent model of unilateral orthotopic lung transplantation.

DESIGN

Eighteen Sprague-Dawley ACI rats underwent removal of their left lung followed by orthotopic transplant of either an allogeneic (PVG, immunologically mismatched; N = 10) or a syngeneic (ACI, immunologically matched) pulmonary graft (N = 8). Animals were imaged 1 h after IV injection of 1 mCi (37.0 MBq) of (99m)Tc-annexin V 1 to 7 days after transplantation.

RESULTS

Lungs receiving the allograft demonstrated moderate to marked mononuclear infiltration of the perivascular, interstitial, and peribronchial tissues. No mononuclear infiltrates were noted in the native right lungs nor in the syngeneic transplants. Region of interest image analysis revealed significant (p < 0.0005) increases of transplant to normal lung activity ratios 3 to 7 days after allograft surgery. The increased annexin V uptake in these lungs was confirmed at biodistribution assay (allograft 151% greater than isograft activity, p < 0.005).

CONCLUSIONS

Acute experimental lung transplant rejection can be noninvasively identified using (99m)Tc-annexin V. Radiolabeled annexin V may be a clinically useful noninvasive screening tool for acute rejection.