Introduction: Recent immunological assays based on the measurement of released interferon-gamma after stimulation of T-cell responses with Mycobacterium tuberculosis specific antigens (IGRAs) have been developed for the immunodiagnosis of latent tuberculosis infection (LTBI). A major concern about the use of IGRAs in children regards the possibility of higher frequency of indeterminate results, because their immune system can still be immature. Aim of this study was to evaluate the frequency of indeterminate results in children and their possible association with diagnosis. Methods: We retrospectively evaluated the routine use of Quantiferon-TB Gold In-Tube (QFT-IT; Cellestis, Australia) on 445 children at the Pediatric Pneumology Unit of S. Orsola-Malpighi General Hospital during the period April 2007-August 2012. Patients were divided by age groups as follows: < 2 years old (n=122), 2-5 years old (n=151), 5-10 years old (n=126) and 10-17 years old (n=66). Results: In our pediatric population: mean age was 5.4 ± 3.9 years, 246 (55%) were male, 99 (22%) were not Italy-born, 179 (40%) were born in Italy from immigrant families and 167 (38%) were Italian. QFT-IT was positive in 70 (16%) children, negative in 353 (79%) and indeterminate in 22 (5%). All indeterminate QFT-IT results in this study were due to an inadequate response to PHA; 3 patients had a known iatrogenic immunosuppression. Indeterminate results were not statistically distributed among different age groups (p=0.386). Diagnosis was available in 321 (72%) children: 30 (9%) were diagnosed as LTBI, 38 (12%) as active TB, 34 (11%) as pneumonia, 219 (68%) were exposed to a TB case. Indeterminate QFT-IT results were distributed as follows: 0% in LTBI, 0% in active TB, 0.5% in exposed to a TB case and 23.5% in pneumonia. A statistically association with diagnosis of pneumonia was observed (p=0.0001). Conclusion: These preliminary data suggest that age hasn’t effect on frequency of indeterminate QFT-IT results, supporting the use of this immunological test in young children. In our population pneumonia seems a risk factor associated with indeterminate QFT-IT. Immunological anergy due to pneumonia should been further investigated.
Indeterminate Quantiferon-TB Gold In-Tube results in children: association with pneumonia?
LOMBARDI, GIULIA;DAL MONTE, PAOLA;PACE, ANTONELLA;BACCHI REGGIANI, MARIA LETIZIA;LANDINI, MARIA PAOLA
2013
Abstract
Introduction: Recent immunological assays based on the measurement of released interferon-gamma after stimulation of T-cell responses with Mycobacterium tuberculosis specific antigens (IGRAs) have been developed for the immunodiagnosis of latent tuberculosis infection (LTBI). A major concern about the use of IGRAs in children regards the possibility of higher frequency of indeterminate results, because their immune system can still be immature. Aim of this study was to evaluate the frequency of indeterminate results in children and their possible association with diagnosis. Methods: We retrospectively evaluated the routine use of Quantiferon-TB Gold In-Tube (QFT-IT; Cellestis, Australia) on 445 children at the Pediatric Pneumology Unit of S. Orsola-Malpighi General Hospital during the period April 2007-August 2012. Patients were divided by age groups as follows: < 2 years old (n=122), 2-5 years old (n=151), 5-10 years old (n=126) and 10-17 years old (n=66). Results: In our pediatric population: mean age was 5.4 ± 3.9 years, 246 (55%) were male, 99 (22%) were not Italy-born, 179 (40%) were born in Italy from immigrant families and 167 (38%) were Italian. QFT-IT was positive in 70 (16%) children, negative in 353 (79%) and indeterminate in 22 (5%). All indeterminate QFT-IT results in this study were due to an inadequate response to PHA; 3 patients had a known iatrogenic immunosuppression. Indeterminate results were not statistically distributed among different age groups (p=0.386). Diagnosis was available in 321 (72%) children: 30 (9%) were diagnosed as LTBI, 38 (12%) as active TB, 34 (11%) as pneumonia, 219 (68%) were exposed to a TB case. Indeterminate QFT-IT results were distributed as follows: 0% in LTBI, 0% in active TB, 0.5% in exposed to a TB case and 23.5% in pneumonia. A statistically association with diagnosis of pneumonia was observed (p=0.0001). Conclusion: These preliminary data suggest that age hasn’t effect on frequency of indeterminate QFT-IT results, supporting the use of this immunological test in young children. In our population pneumonia seems a risk factor associated with indeterminate QFT-IT. Immunological anergy due to pneumonia should been further investigated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
