IGHG3 and acute myeloid leukemia: Our search for AML-specific antibodies in patients with AML with potent GvL responses, as described above, uncovered many antibodies of interest, most of which were of the IgG3 isotype (and some of the IgG1 isotype).32, 33, 34 This confirms the findings of others, who also found dominance of IgG1 and IgG3 antibodies.41