Two distinct chemotactic factor inactivators in human serum.

The chemotactic factor inactivator (CFI) has been isolated from whole human serum by a combination of techniques including salt precipitation, anionic exchange, and gel filtration chromatography. Two inactivators have been obtained, a beta-globulin with a sedimentation velocity of approximately 7S and an alpha-globulin with a sedimentation velocity of approximately 4S. The former has a specificity for inactivation of the chemotactic activity associated with the C3 fragments, whereas the C5 chemotactic fragment is specifically inactivated by the alpha-globulin CFI. CFI in crude fractions of human serum is heat labile, time and temperature dependent for its activity, and pH dependent, expressing optimal activity at a pH range of 7.2 to 7.4.