Selective IgM digestion improves anti-AAV IgG detection in the immune complex assay format

To confirm the observation of IgM interference in the anti–adeno-associated virus (AAV) IgG immune complex (IC) assay format and to verify that IgM-specific digestion can improve anti-AAV IgG detection in IC assays. Treatment-emergent anti-AAV2 and anti-AAV9 IgG signals were measured in IC assays with and without IgM-specific digestion. Anti-AAV2 and anti-AAV9 IgM signals were measured in parallel. IgM digestion increased anti-AAV2 and anti-AAV9 IgG signals when anti-AAV2 or anti-AAV9 IgM were present in the matrix. Co-existing anti-AAV IgM cause interference in the anti-AAV IC assay format. Selective IgM digestion improves the detection of anti-AAV IgG in the IC assay.