Haemolytic complement in peripheral lymph of normal men.

The haemolytic activity of nine individual components of complement and the concentrations of C1q, C1s, C4, C3, C3PA and C9 proteins were measured in the leg lymph and serum of four normal men. The mean lymph/serum ratio for total haemolytic complement was 0.257, for C1H50 it was 0.138, for C4H50 0.105, for C2H50 0.279, for C3H50 0.063, for C5H50 0.266, for C6H50 0.145, for C7H50 0.25, for C8H50 0.244 and for C9H50 0.253. The mean lymph/serum ratio for complement proteins was: for C1q 0.048, for C1s 0.06, for C4 0.199, for C3 0.225, for C9 0.244 and for C3PA 0.263. The low haemolytic activity of total complement and of all components in lymph seems to be dependent on the low complement protein concentration. The remarkably low lymph C1q protein concentration may play a physiological role in controlling total complement activity in lymph and interstitial fluid. The total complement haemolytic activity in lymph exceeded the haemolytic activity of C1 and C3, which may indicate the possibility of independent activation of C5-7 and C8-9. The considerably low C3H50 level, with high C3 protein concentration, at present lacks a proper explanation.