Figure 3.

Binding of IgG/IgM domain-swap and monomeric point mutants to hFcα/μR transfectants assessed by IFA on fixed and permeabilized cells. Fcα/μR expression (green) was detected as in Fig. 1. Binding of test Ab was detected with an anti-mouse λ L chain-PE conjugate (red) that bound to the common L chain shared by all the test Ab. hFcα/μR bound only WT IgM and the γ/Cμ3,4 domain-swap Ab.