This disclosure relates to dimeric immunotherapeutics that comprise two IgGs that are crosslinked with a disulfide bond. The two IgGs may be chimeras of two different heavy chains, in which one heavy chain includes a cysteine mutation that forms the disulfide bond, and the other heavy chain lacks the cysteine mutation. The presence of a cysteine mutation in only one of the heavy chains of an IgG avoids two disulfide bonds between the two IgGs, which increases the accessible orientations between the two crosslinked IgGs, and also avoids the formation of trimers and higher-order oligomers.