Figure 1.
Isolation of KZ30.6 T-cell-stimulating antigen gene, 39G3.9, by expression cloning. (A) Pools of an EL-4 cDNA library were transiently transfected into Kb-COS cells in 96-well plates. Two days later lacZ-inducible KZ30.6 T cells were added to the wells and after an overnight incubation, assayed for the induction of lacZ activity measured by the color change due to conversion of the CPRG substrate. Representative absorbance data is shown for a single 96-well plate containing the postive pool 39G3 that was selected for further fractionation. (B) DNA from individual bacterial colonies of the pool 39G3 were assayed for their ability to stimulate KZ30.6 T-cell response. Plasmid 39G3.9 was active in generating the KZ30.6-stimulating ligand and was selected for further analysis.