ALTERNATIVE PATHWAY OF BOVINE COMPLEMENT - IMMUNOCHEMICAL STUDIES ON FACTOR B-LIKE SERUM-PROTEIN AND ITS CONVERSION PRODUCT B-GAMMA-2

  • 1 January 1981
    • journal article
    • research article
    • Vol. 45  (3) , 291-298
Abstract
Rabbits produced antibodies to a factor B-like serum protein (factor Bbov), its conversion product B.gamma.2 and some other bovine serum proteins after repeated immunization with zymosan which was previously incubated with fresh bovine serum. Such antisera were used to monitor purification of B.gamma.2 from fresh bovine sera incubated with zymosan. Subsequently, antisera specific for factor Bbov and B.gamma.2 were produced. Antiserum produced against B.gamma.2 cross-reacted with factor Bbov. Functional assays for factor Bbov were carried out in a hemolytic system with guinea pig erythrocytes in EGTA buffer. Heat inactivation (56.degree. C/5 min) of bovine serum destroyed the antigenicity of factor Bbov but not that of B.gamma.2. Factor Bbov had an apparent MW of 95,000 and B.gamma.2 a MW of 40,000 daltons. Conversion of factor Bbov to B.gamma.2 was determined qualitatively by immunoelectrophoresis and quantitatively by radial immunodiffusion. Conversion of factor Bbov to B.gamma.2 in bovine serum, in the presence of zymosan or cobra venom factor, required Mg2+ but not Ca2+, did not occur in heat-inactivated (56.degree. C/5 min) serum and was maximal, but not complete, when fresh bovine serum was incubated with zymosan (20 mg/ml) at 37.degree. C for 2 h.