Increased lymphoid MxA expression in acute asthma exacerbation in children.
BACKGROUND
Although the association between acute asthma exacerbation and viral infection has been well documented, virus identification rates vary. It has recently been reported that the expression of MxA protein in lymphocytes, inducible by type I interferons, can serve as a sensitive marker for viral infection in the host. The objective was to determine the contribution of viral infection to precipitation of asthma attacks in children.


METHODS
We studied 186 asthmatic children, aged 0-12 years, over a 1-year period to evaluate MxA protein levels in peripheral blood lymphocytes by using a flow cytometric analysis in whole blood.


RESULTS
Of all the subjects, 80 (47%) exhibited significantly elevated levels of MxA expression in lymphocytes, presumably indicating the states of viral infection. The association of viral infections with acute asthma exacerbation seemed to be marked in younger children: enhanced MxA expression was seen in 73.3% of infants (aged 0-1 year), 49.5% of toddlers (aged 2-5 years), and 26% of schoolchildren (aged 6-12 years). Seasonal changes in the frequency of viral infection associated with deterioration were also observed.


CONCLUSIONS
Flow cytometric assay of MxA protein expression in whole blood appears to be an easy and useful method to evaluate viral infections in acute asthma exacerbation.
Itazawa
T
T
Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.
Adachi
Y
Y
Imamura
H
H
Okabe
Y
Y
Yamamoto
J
J
Onoue
Y
Y
Adachi
Y S
YS
Miyawaki
T
T
Murakami
G
G
D000208:Acute Disease; D000367:Age Factors; D001249:Asthma / Q000378:metabolism* / Q000503:physiopathology*; D002648:Child; D002669:Child Welfare; D002675:Child, Preschool; D005260:Female; D005434:Flow Cytometry; D005453:Fluorescence; D005500:Follow-Up Studies; D019204:GTP-Binding Proteins; D006801:Humans; D007223:Infant; D007229:Infant Welfare; D007231:Infant, Newborn; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D064547:Myxovirus Resistance Proteins; D014176:Protein Biosynthesis; D012621:Seasons
C579071:MX1 protein, human; D064547:Myxovirus Resistance Proteins; D019204:GTP-Binding Proteins