Aggregation assays of PRR2 transfectants. (A) Short-term kinetic. Values are the mean ± SE for three independant experiments and correspond to the number of aggregates (n > 3 cells) per microliter. (▪) Da1/PRR2 cells; (□) Da1/PRR2δ cells; (×) Da1 cells. (B) PRR2-Fc (20 μg/mL) or fab fragment of R2.477 MoAb (20 μg/mL) inhibits aggregation. The number of aggregates was counted after 60 minutes of incubation. (▨) Da1; (▪) Da1/PRR2; (□) Da1/PRR2δ. The mock control corresponds to a murine irrelevant IgG1 (20 μg/mL).