FIGURE 2:

Microspheres bearing CD16 bound RBCs coated with hIgG1 specifically. (A) Adhesion frequency of CD16 lysate–coated microspheres to hIgG1-coated RBCs was substantially higher than the nonspecific adhesions, controlled using a blocking anti-CD16 (3G8) or microspheres incubated with BSA (instead of lysates of CD16 expressing CHO cells) or RBCs not coated with anything. N.D., not done. Adhesion frequencies were measured with a 2-s contact duration. (B) Adhesion frequency vs. contact duration (t) binding curves. The two sets of data (points) were obtained using RBCs coated with hIgG1 to contact 214.1-precoated microspheres incubated with lysates from CHO cells expressing CD16a^TM (filled diamonds) or plain CHO cells (open diamonds). For the former, the specific adhesion frequency P_a after removing the nonspecific adhesion frequency (Eq. 1) is shown and fitted by Eq. 2 (curve). Data are mean ± SEM of five RBC-microsphere pairs with 100 contacts each per bar or point.