To function as an agonist, it has been suggested that TGN1412 needs to be a whole antibody, including the constant (Fc) region. According to a report by TeGenero, the F(ab)2 is not able to generate the required stimulation. Unlike the related clone TGN1112, an IgG1, TGN1412 is of the subclass IgG4. This choice was made as TGN1112 showed antibody-dependent cellular cytotoxicity on CD28+ Jurkat cells. Thus the function of antibody binding via an Fcγ receptor seems to be a requirement for the immune regulation. However, cell opsonisation by antibody leads normally to phagocytosis of the labeled cells, as seen in the case of HIV.