PURPOSE OF THE STUDY.
Human rhinovirus C (HRV-C), compared with HRV-A and HRV-B, has been associated with more severe asthma attacks in children presenting to the hospital. The purpose of this study was to compare the antibody response to each HRV in asthmatic children who had a known HRV infection.
Ninety-six children who presented with acute asthma exacerbations to the emergency department of Princess Margaret Hospital for Children (Australia) and 47 nonasthmatic control children were included in the study. Most of the ED asthmatic subjects (95.6%) required hospital admission for moderate to severe acute asthma attacks.
Paired acute and convalescent plasma from 96 children with acute asthma were compared. Peripheral blood samples were obtained within 24 hours of presentation and stored at –80°C. Convalescent samples were obtained either 6 to 26 weeks after initial recruitment (median 12 weeks) or >26 weeks after the initial recruitment (median 34 weeks) at scheduled visits when the subject was clinically well. Forty-seven nonasthmatic control children had serum collected in a similar fashion. Nasal secretions from each subject was tested for HRV by direct fluorescent antibody testing and also analyzed by molecular typing assay to determine which HRV strains were present. Immunoglobulin G1 antibody titers were quantified with a dissociation-enhanced immunofluorescence assay.
Asthmatic children had higher antibody responses to HRV-A and HRV-B than nonasthmatic controls. The responses to HRV-C were markedly lower than titers to HRV-A and HRV-B in both asthmatic and nonasthmatic children (P < .001). Titers at presentation and after convalescence were not associated with the HRV genotype detected during the exacerbation.
Higher total anti-HRV-A and anti-HRV-B titers in asthmatic children show the development of heightened antiviral immune response. Low species-specific HRV-C titers in both study groups, even when virus was detected, suggest a possible altered, less efficacious immune response to this species.
HRV infection has previously been demonstrated in a significant proportion of children presenting with moderate to severe asthma exacerbations. This study now demonstrates that suboptimal immune response specifically to HRV-C infection may explain part of this observation. If we continue to develop our understanding of this observation, we may someday be able to discover alternative interventions to prevent severe asthma exacerbations, which still occur despite aggressive treatment with appropriate asthma controller medications.
- Copyright © 2015 by the American Academy of Pediatrics