CD19 and infection: ,29,30,31 As second TM protein, a dimerized, surface-tethered interleukin (IL)-13 allowed a specific infection of IL-13Rα1-expressing cells,30 while a TM version of an anti-CD19 single-chain antibody fragment (scFv) efficiently infected CD19+ B cell lines, but not CD19- T cell lines,30 as well as CD19-expressing HEK293T, but not the parental HEK293T cell line.28