Identification of ‘cystic fibrosis protein’ as a complex of two calcium-binding proteins present in human cells of myeloid origin

Cystic fibrosis protein is a serum protein characterized by a pI close to 8.4 and present with a higher concentration in serum and plasma of cystic fibrosis carriers than in controls. This protein was found immunologically indistinguishable from the cystic fibrosis antigen isolated from granulocytes and presenting a sequence analogous to that of MRP-8, a calcium-binding protein expressed in the myeloid cell lineage. Using antibodies directed against MRP-8 and its closely associated calcium-binding protein, MRP-14, we demonstrate here that cystic fibrosis protein purified from serum is a complex of the two proteins MRP-8 and MRP-14.