Mannose-binding lectin is present in the infected airway: a possible pulmonary defence mechanism.
BACKGROUND
Mannose-binding lectin (MBL) deficiency has been associated with infections of the respiratory tract and with increased disease severity in cystic fibrosis (CF). The mechanism is uncertain, and could relate either to systemic or local effects. The aim of this study was to determine, in a large cohort of children, whether MBL is present on the airway surface in health or disease.


METHODS
Bronchoalveolar lavage (BAL) fluid from children with and without respiratory infection (some with underlying disease) was analysed for MBL and neutrophil elastase (NE). Levels were compared between groups, and correlations were examined with local and systemic inflammatory markers, infective organisms and load.


RESULTS
85 children were recruited to the study. MBL was absent in the lavage of all 7 children without lung infection but present in 62% (8/13) of those with acute pneumonia/pneumonitis, 23% (5/22) with recurrent respiratory tract infections, 17% (1/6) with primary ciliary dyskinesia and 8% (3/37) with CF (p<0.01). Children with acute pneumonia/pneumonitis had significantly higher levels than those in the other groups. There was no relationship with organisms cultured or systemic markers of inflammation, although in the group with detectable MBL in the BAL fluid, the levels correlated positively with levels of NE.


CONCLUSIONS
MBL is undetectable in the non-infected airway but is present in a significant number of samples from children with lung infection. The levels found in the BAL fluid could be physiologically active and the protein may therefore be playing a role in host defence.
Fidler
K J
KJ
Infectious Diseases and Microbiology Unit, Institute of Child Health, London, UK.
Hilliard
T N
TN
Bush
A
A
Johnson
M
M
Geddes
D M
DM
Turner
M W
MW
Alton
E W F W
EW
Klein
N J
NJ
Davies
J C
JC
D000293:Adolescent; D001419:Bacteria / Q000302:isolation & purification; D001980:Bronchi / Q000737:chemistry*; D001982:Bronchial Diseases / Q000378:metabolism* / Q000382:microbiology; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry* / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D007223:Infant; D019272:Leukocyte Elastase / Q000378:metabolism; D008297:Male; D037601:Mannose-Binding Lectin / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D012008:Recurrence; D012141:Respiratory Tract Infections / Q000378:metabolism* / Q000382:microbiology; D014780:Viruses / Q000302:isolation & purification
D037601:Mannose-Binding Lectin; D011480:Protease Inhibitors; D019272:Leukocyte Elastase