Figure 4.

Agonistic activity of GpL-18D1-IgG1 fusion proteins upon oligomerization with protein G and FcγR binding. (A) WiDr cells were stimulated in 96-well plates in triplicates with the indicated concentrations of the various GpL-18D1-IgG1 fusion proteins and 18D1 in the presence and absence of 1 µg/ml protein G. The following day, supernatants were collected and analyzed with respect to IL8 production by ELISA. (B) HEK293 cells were transiently transfected with expression vectors encoding CD16, CD32A CD32B, and CD64 or empty vector. The following day, transfectants were mixed with the indicated concentrations of the various 18D1 variants and after 30 min aliquots of 1.7×10⁴ transfected HEK293 cells per well were added to WiDr cells (2 × 10⁴ / well) grown overnight in 96-well plates. Next day, the IL8 content of the supernatants was determined by ELISA.