Immune Lytic Transformation: A State of Irreversible Damage Generated as a Result of the Reaction of the Eighth Component in the Guinea Pig Complement System

Abstract

Summary Data presented here indicate that during the sequential complement reaction a state of irreparable cellular damage is reached after the reaction of the eighth component, but before the reaction of the ninth component, in the guinea pig complement system. Spontaneous lysis of the EAbC′—8 complex was shown to be similar to the lysis of the classical E* complex (EAbC′—9) in that it proceeded to a greater extent during a fixed incubation in buffer at 0.15 M rel NaCl than in buffer of lower ionic strength; and also in that it was completely inhibited in 0.086 M EDTA. The rate of lysis in an EAbC′—8 population remained almost constant during 180 min at 37°C, whereas, the rate of lysis in a population containing very small numbers of C′9 sites was very much higher at the beginning of the incubation period and decreased rapidly so that by 90 min it was indistinguishable from that of a population of EAbC′—8. This difference in lytic pattern indicates that the lysis of EAbC′—8 is not a reflection of contaminating C′9 sites. The EAbC′—8 complex did not manifest increased lytic susceptibility compared with other stable intermediate complexes in buffers of low osmotic pressure, on subjection to mechanical trauma, or in buffers at pH between 5.0 and 7.5. The EAbC′—8 complex was found to be specifically more susceptible to lysis in the presence of low concentrations of sodium desoxycholate. Further, the lysis of this intermediate in the presence of sodium desoxycholate was found to be similar to its lysis in the presence of C′9 in that it was temperature dependent, and inhibited in buffer of low ionic strength. Under carefully controlled conditions of sodium desoxycholate concentration and incubation time, the amount of lysis of EAbC′—8 was proportional to the average number of C′8 sites per cell in the population.