INVESTIGATIONS ON SELECTED RED-CELL CONCENTRATES FOR TOXOPLASMA AND TOXOPLASMA DNA

Background: The aim of the present study was to detect the occurrence of viable Toxoplasms or the presence of their DNA. Red blood cell conc entrates of specific IgM-positive donors were tested in order to estim ate if such blood products may have an infectious potential when trans fused. Material and Methods: Aliquots of 1,000 red cell concentrates w ere used to inoculate in vitro cell cultures which were examined micro scopically 6-7 days later with fluorescent staining for Toxoplasma gon dii. Additionally, after a DNA isolation procedure, a polymerase chain reaction (PCR) was performed using a part of the sequence of the toxo plasma B1 gene as a target. Dilutions of T. gondii tachyzoites with th e red cell concentrate were used as positive controls. Results: Tachyz oites could be detected by in vitro culture even when the inoculum sta tistically contained only one parasite. About 3 tachyzoites yielded a positive result with the PCR method. All red cell samples investigated gave negative results both in cell culture and PCR. Conclusion: The r isk of transmission of Toxoplasms by transfusing red cell concentrates from specific IgM-positive donors can be considered unlikely.