Some Observations on the Constitution of the Complements of Different Animals

In the past a considerable amount of attention has been paid by serological workers to the complex characters of serum-complement and many attempts have been made to subject complement to more detailed biochemical analysis. Valuable information has thus been obtained regarding the biological action and properties of this important element of animal serum. The study of complement has been principally based on its cytolytic effects towards red blood corpuscles sensitised with the homologous immune body, and the general tendency of research on this subject has been to elicit the complexity of constitution of complement and the numerous factors on which its action depends. The fresh serum of the guinea-pig represents with ox corpuscles + rabbit versus ox immune body or cobra venom, one of the most active complements and it has therefore been commonly used for studies on complement action. Attention was first drawn by Stephens (1) to the hemolytic effect of certain snake venoms along with fresh serum. In the case of guinea-pig’s serum, which has a powerful activating effect, this characteristic property is annulled by heating the serum at 55°C. and corresponds as regards thermolability to the complementing action of serum with immune body. Observations made by Browning and Mackie (2) on the complementing action of serum with immune body in relation to its hemolytic effect with cobra venom showed that the venom-activating constituent of serum though similar in many characters to the complement which acted with immune body was not identical with the latter. Ferrata (3) and later Brand (4) Liefman (5) Sachs (6) demonstrated that complement could be fractioned into two components neither of which exhibited any degree of complementing effect by itself, although together they reproduced the full hemolytic activity of the native serum. These two moieties were designated “end-piece” and “mid-piece” the latter combining directly with red blood corpuscles + immune body.