| Abstract: | By gene-engineering technique a chimeric protein made up of fragments of Staphylococcus aureus protein A and .Pseudomonas aeruginosa exotoxin A has been constructed. The chimeric protein was shown to preserve features characteristic of its both constituents--it ADP-ribosylates elongation factor 2 and binds to Ig. Cytotoxic properties of the chimeric protein were studied in two model systems. Treatment of target cells in both systems was performed successively with antibodies against corresponding antigens and after washing--with recombinant chimeric toxin which bound to antibodies on the surface of target cells. In the first model system human B-lymphoma cells (Daudi line) carrying Ig molecules on their surface were treated with polyclonal antibodies against human Ig L-chains. In the other system, human T-lymphoma cells (Jurkat line) were treated successively with monoclonal antibodies against cell surface CD5 antigen and further on--with polyclonal antibodies against mouse Ig. In both systems, only a slight inhibition of the target cells' growth was registered. The probable reasons of low cytotoxic activity of the chimeric protein and prospects of increasing it are discussed. |
