Physical association of CD22 with the BCR seems to have direct involvement in the regulation of BCR signalling, as antibody-mediated clustering of CD22 with the BCR leads to dampened signaling (Smith et al. 1998), and evidence of their association has been obtained by confocal microscopy, coimmunoprecipitation and chemical crossing (Zhang et al. 2004, Phee et al. 2001, Peaker et al. 1993, Law et al. 1994, Leprince et al. 1993, Collins et al. 2006). Forced ligation of CD22 to the BCR dramatically increases CD22 phosphorylation and suppression of BCR signalling (Macauley, 2013). This is relevant to suppression of BCR signalling to membrane antigens on B cells that contain self sialic acids (Lanoue, 2002; Macauley 2013). CD22 ligand binding modulates its activity as a negative regulator of B cell signalling.