Serum complement C2 levels in patients suffering from cystic fibrosis (CF).

Serum C2 complement levels were measured in 17 children suffering from CF, 17 with obstructive bronchitis, and 7 control children. No correlation was found between the C2 level and the clinical stage in Shwachman score, the HLA B7 or B18 antigens and the ventilation functional parameters. The mean serum C2 complement level did not differ in the three investigated groups, but in 5 of the 17 CF patients the serum C2 was diminished according to the possibility of C2 complement heterozygosity. The CF patients with diminished C2 complement levels exhibited HLA B7, B12 or B35 antigens. The serum C2 complement levels were significantly higher in the HLA B18 antigen-carrier CF homozygotes.