Alternative complement pathway activity in cystic fibrosis [letter].

The possibility has been raised that complement plays a role in the 
pathogenesis of cystic fibrosis (CF). This impairment would be consistent with 
the thesis that the alternative pathway had been activated in vivo 
and, therefore, depleted. The purpose of this work is to explore 
further the function of the alternative pathway in cystic fibrosis. Examination 
of the data using Student's t test and analysis of variance 
showed no significant difference in the mean hemolytic activity of sera 
of CF patients as compared to the control group. The data 
presented do not support the work of Polley and Bearn who 
demonstrated an abnormality in CF patients using conversion of C3 by 
inulin as assay. The reason for this discrepancy is not clear. 
Our results do not preclude in vivo activation of the alternative 
pathway, since a compensatory increase in synthesis of components could offset 
component consumption. Since the net result is a completely normal level 
of activity, however, it does not seem likely that significant consumption 
has occurred. 