An Investigation of Some of the Factors Determining the Decrease in Complement Activity in Anaphylactic Shock

Abstract

Summary Guinea pigs actively sensitized to egg albumin mixed with adjuvants developed more acute symptoms of shock and showed a more pronounced and rapid fall in complement titer when challenged intravenously 6 weeks later than did similar groups sensitized to egg albumin without adjuvants. The change in C′ titer tended to be greatest in the guinea pigs exhibiting very severe respiratory symptoms. Fatal protracted shock followed the intraperitoneal injection of large amounts of antigen in highly sensitized guinea pigs, but the decrease in complement activity was usually less pronounced than in the intracardially-challenged animals dying within a 10-minute interval. Actively and passively sensitized guinea pigs in which fatty livers and a marked fall in C′ titer had been induced previously through repeated injection of ethionine, exhibited respiratory symptoms as acute as the sensitized controls. Less severe respiratory symptoms were recorded on challenge in actively-sensitized guinea pigs that had been treated with gum acacia for several weeks to induce low C′ titers; symptoms of initial excitement with subsequent weakness were more conspicuous. In both groups of sensitized guinea pigs, complement titers declined further on challenge. In passively sensitized guinea pigs, challenged soon after intraperitoneal injection of antiserum, the change in C′ titer was negligible, even though some of these animals developed symptoms of slight to moderate shock. A rapid and striking fall in C′ titer occurred in guinea pigs of the same groups that experienced acute shock following intravenous challenge 18 hours to 7 days after injection of antiserum.