Establishing Simultaneous T Cell Receptor Excision Circles (TREC) and K-Deleting Recombination Excision Circles (KREC) Quantification Assays and Laboratory Reference Intervals in Healthy Individuals of Different Age Groups in Hong Kong.

The clinical experience gathered throughout the years has raised awareness of primary immunodeficiency diseases (PIDD). T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC) assays for thymic and bone marrow outputs measurement have been widely implemented in newborn screening (NBS) programs for Severe Combined Immunodeficiency. The potential applications of combined TREC and KREC assay in PIDD diagnosis and immune reconstitution monitoring in non-neonatal patients have been suggested. Given that ethnicity, gender, and age can contribute to variations in immunity, defining the reference intervals of TREC and KREC levels in the local population is crucial for setting up cut-offs for PIDD diagnosis. In this retrospective study, 479 healthy Chinese sibling donors (240 males and 239 females; age range: 1 month-74 years) from Hong Kong were tested for TREC and KREC levels using a simultaneous quantitative real-time PCR assay. Age-specific 5th-95th percentile reference intervals of TREC and KREC levels (expressed in copies per µL blood and copies per 106 cells) were established in both pediatric and adult age groups. Significant inverse correlations between age and both TREC and KREC levels were observed in the pediatric age group. A significant higher KREC level was observed in females than males after 9-12 years of age but not for TREC. Low TREC or KREC levels were detected in patients diagnosed with mild or severe PIDD. This assay with the established local reference intervals would allow accurate diagnosis of PIDD, and potentially monitoring immune reconstitution following haematopoietic stem cell transplantation or highly active anti-retroviral therapy in the future.

Rhinovirus infection in hospitalized children in Hong Kong: a prospective study.

OBJECTIVES: To analyze the clinical features and estimate the hospitalization disease burden of rhinovirus infection in children in Hong Kong. METHODS: In this prospective study, nasopharyngeal aspirates were taken from children aged <18 years with symptoms of acute respiratory infection admitted to Queen Mary Hospital on one fixed day of the week during August 2001-July 2002 for detection of common respiratory viruses by immunofluorescence, viral culture, and for rhinovirus, human metapneumovirus, and coronaviruses by reverse transcription polymerase chain reaction. The clinical features of rhinovirus infections were analyzed and hospitalization disease burden was estimated. RESULTS: Altogether 239 of the 426 nasopharyngeal aspirates (56.1%) were positive for respiratory viruses, including 151 patients with rhinovirus (35.4%). The median age was 2.34 years. Upper respiratory infection, asthma exacerbation, pneumonia, and acute bronchiolitis were diagnosed in 44.4%, 19.9%, 11.3%, and 7.9%, respectively. The most common symptoms were cough (81.5%), runny nose (76.8%), and fever (68.9%). Shortness of breath, wheezes, and crepitation were present in 25.8%, 29.1%, and 18.5%, respectively. Fifty-five of 99 patients (55.6%) had chest radiographic abnormalities, most commonly perihilar streakiness. Children with chronic diseases were more likely to have lower respiratory tract infection and these children required longer hospitalization (mean 0.6 days longer). Coinfection with other respiratory pathogens was common (33.1%). CONCLUSION: Rhinovirus is frequently associated with asthmatic exacerbations and lower respiratory tract infection, especially in children with chronic diseases and is potentially an important contributor to hospitalization in children in Hong Kong.