Platelet3H-Serotonin Releasing Immune Complexes Induced by Pseudomonas aeruginosa in Cystic Fibrosis

Abstract

In vitro formation of immune complexes was studied by 3H-serotonin release from human platelets by P. aeruginosa antigens in the presence of serum from 22 cystic fibrosis patients, chronically infected with mucoid P. aeruginosa (CF + P) and with a pronounced antibody response against these bacteria, and in 24 patients without P. aeruginosa (CF-P). All CF + P patients responded with 3H-serotonin release (16-34%); CF-P patients released < 15%. In the group of CF + P patients, the number of P. aeruginosa precipitins was correlated to the serotonin titer. Time courses indicated that 3H-serotonin release was maximal between 2-5 min; no further release was observed up to 20 min. There was a gradual increase in 3H-serotonin release with higher platelet concentrations. The response was not changed by complement inactivation; fractionation of serum demonstrated that the serotonin release was dependent on the presence of the Ig fraction. Thus, a type III reaction may be involved in the lung damage in CF + P patients. A possible involvement of serotonin in the inflammatory reaction during chronic P. aeruginosa lung infection was suggested.