The Action of Ammonia on Complement. The Fourth Component

Abstract

DURING a study of the action of pancreatic extracts on complement [Wormall, Whitehead and Gordon, 1925], we became interested in the possible action of lipase, thinking that it might throw some light on the part played by fats and lipins in complement action. The chief difficulty was to obtain lipase preparations free from proteoclastic enzymes, for trypsin preparations have a destructive action on both the albumin and globulin fractions of serum. Eventually we used the enzyme preparation of Willstaitter and The preparation consists of a suspension of purified lipase in an ammoniacal phosphate solution containing glycerol, and the results obtained by its action on complement indicated that the destruction of a hitherto unknown factor had occurred. A control experiment, however, showed that the boiled enzyme solution had the same function, and by a process of elimination it was found that the active agent was really the ammonia. In effect, the addition of ammonia (or ammonium salts and alkali) to com- plement and incubation at 370 for 1-2 hours, destroyed the power to haemolyse sensitised red blood cells. The activity of the serum could be restored by the addition of complement which had been heated to 560 and which was by itself inactive. The ammonia thus appeared to have destroyed some relatively heat-stable component of complement.