Employing the crossed immunoelectrophoresis technique (CIE) the antigenic composition of fibrinogen chains and heterogeneity in their electrophoretic mobility was investigated.Highly purified chains of fibrinogen were prepared by chromatography on CM-cellulose (1). Antisera against chains were prepared by immunizing rabbits with Aα, Bβ and γ chains respectively. The CIE was performed on 10 × 10 glass plates with an 1 mm thick layer of 1% agarose in 0.04 M barbital buffer pH 8.6. The electrophoresis was run for 1 h with 12 V/cm. Four fifth of the gel was cut off and replaced with the same agarose solution containing antibodies. The second dimension electrophoresis was run for about 20 h with 2 V/cm.Using anti Bβ chain serum a partial immunological identity was revealed between the Bβ chain and the γ chain. The Bβ chain has except for the antigenic sites in common with the γ chain additional sites that are unique for the B β chain. The results were confirmed with the anti γ chain serum which gave a strong reaction with both the γ chain and the B β chain preparations. The Aα chain did not react with γ antiserum, nor did the γ chain react with anti Aα chain serum. The immunological relation between the Aα chain and the B β chain is under investigation.These experiments also concluded that the γ chain preparation is contaminated with a B β chain variant that has an electrophoretic mobility similar to that of the γ chain. Also the Bβ chain seemed to be impure due to contamination by an Aα chain derivative with higher electrophoretic mobility.(1) Murano, G., Wiman, B., Blomböck, B. and Blomböck, M. : Preparation and isolation of the S-carboxymethyl derivative chains of human fibrinogen. F.E.B.S. Letters: 14, 37, 1971.
