FIGURE 6.

BCR signaling is not required for Ag-BCR association with MHC class II molecules. A, A20μWT B cells were pretreated with 100 μm PP2 (an Src kinase inhibitor) for 20 min at 37 °C or left untreated. The cells were then pulsed with PC-BSA-btn for the indicated time, and PC-BSA-btn—BCR—class II complexes (cmplx) were isolated and analyzed as in Fig. 1. Shown are representative results from one of three independent experiments (the ECL exposure for the cmplx blots of control and PP2-treated cells was identical). B, quantitative analysis of the average level of PC-BSA-btn-BCR—class II complex levels in control and PP2-treated cells across three independent experiments.