FcαRI can initiate 3 different outcomes depending on the mode of interaction with its ligand. (1) Cross-linking of FcαRI (eg, via IgA-opsonized bacteria) results in a heavily phosphorylated (p) FcR γ chain ITAM, which engages Syk and leads to activation. (2) Weak phosphorylation of FcR γ chain ITAM after monomeric FcαRI targeting recruits SHP-1, hereby eliciting an inhibitory signal. SHP-1 also seems to suppress apoptosis. (3) In the presence of additional (unknown) signals, monomeric triggering of FcαRI results in apoptosis of monocytes. Although the signaling pathway has not been elucidated, FcR γ-chain ITAM is critically involved in this process as well.