Immunochemical studies of the plasma and cultured fibroblast media fractions containing the cystic fibrosis ciliary inhibitor.

The cystic fibrosis ciliary inhibitor (CFCI) has been fractionated from plasma of 
cystic fibrosis (CF) homozygotes and from the media of cultured fibroblasts 
derived from CF homozygotes. Plasma and fibroblast media from normal controls 
have been fractionated in an identical manner. Fractions from plasma and 
fibroblast culture media that demonstrate ciliary inhibitory activity contain several proteins 
in a molecular weight range of approximately 5,000-11,000. These proteins have 
been partially characterized by immunochemical analysis with antisera to 33 human 
serum proteins. Immunological determinants of albumin, C3 (but not C3a), C4, 
C5, alpha1-lipoprotein, beta- lipoprotein, beta2-microglobulin and immunoglobulin light chains have been 
detected by hemagglutination in fractions of CF plasma that inhibited ciliary 
activity and in analogous fractions from normal sera. None of the 
proteins were detected in media of cultured fibroblasts from either genotype. 
Since the same proteins and protein fragments were identified in both 
CF and normal plasma fractions, and were not detected in CF 
fibroblast media, it appears that none of these proteins can be 
identified as the CFCI. Identification of these proteins will permit further 
purification of the CFCI by immunochemical methods. 