Enzyme-linked immunoassay and electrophoretic separation of collagens secreted by cultured skin fibroblasts of patients with Ehlers-Danlos and Marfan syndromes.

A method for the quantitation of the collagen types I, III, IV, and V, synthesized by cultured dermal fibroblasts is described. Collagens precipitated from the culture medium and intracellular collagens were detected by enzyme-linked immunosorbent assays with rabbit polyclonal monospecific antibodies. The assay could detect 10 ng protein per well, and intraassay coefficients of variation were less than 5%. Secreted collagens types I and III were also analysed by electrophoretic separation of [3H]-labelled alpha-chains under nonreducing and reducing conditions. These methods revealed a structural abnormality in one patient with clinical features of Marfan syndrome, and led to the postulation that the abnormality resulted from substitution of cysteine for another amino acid in collagen type I. In other patients an increase in the ratio of collagen type III:type I was detected, which may be secondary to an unknown biochemical defect.