COMPLEMENT KILLING OF YERSINIA-ENTEROCOLITICA AND RETENTION OF THE BACTERIA BY LEUKOCYTE REMOVAL FILTERS

We report studies on the complement sensitivity of four strains of Yer sinia enterocolitica, serotypes 0:3, 0:9, 0:5,27, and 0:20, isolated f rom blood units involved in transfusion fatalities. Complement in fres h CPD plasma killed Y. enterocolitica within 4h at 22 degrees C in 100 % of the experiments. The bactericidal action was serotype and complem ent activation pathway dependent. Both classic and alternate pathways seemed to be active, but the latter to a lesser degree. When the class ic pathway was blocked by chelation of Ca2+ no complete killing was ob tained. Complement did not enhance or condition Yersinia for leucocyte filter retention. Direct removal of Yersinia by filtration was also r elated to serotype; all strains were reduced by filtration in heat-ina ctivated plasma, and all except serotype 0:5,27 were reduced in Ca2+-c helated plasma. Our findings may explain why plasma products and plate let concentrates are rarely involved in Yersinia sepsis related to tra nsfusion.