Serial determination of complement and specific antibody titres in Pseudomonas aeruginosa infection.

Serial examination of the complement system and specific antibody titre of 12 surviving patients and 8 lethal cases suffering from Pseudomonas aeruginosa infection showed that except the onset of infection, until the development of septic shock, the level of the complement components corresponded to or exceeded the average normal value. In reversible septic shock the complement titre decreased significantly and in irreversible shock the values were even lower. Activation of the complement system occurred on 10 occasions via the classical and on 42 occasions via the alternative pathway. The number of activations grew parallel with the severity of the infection. Activation through the classical way was generally more intensive. During the whole infectious process not the individual characteristics of the P. aeruginosa present unbroken, but the pathological events and the specific antibody level determined the mode (alternative or classical pathway) of complement activation. The specific antibody level of the surviving patients significantly surpassed the titres of the lethal cases until the development of shock. Not an insufficiency of the complement system but the relative lack of specific antibodies was mainly responsible for the fatal outcome of P. aeruginosa infections.