FcγRIV, also known as CD16-2, is an intermediate-affinity activating receptor for IgG2a and IgG2b. It is expressed on peripheral blood leukocytes, spleen, thymus, colon, and the intestine. CD16.2 is the mouse homolog of human Fcγ RIIIA. CD16.2 is a low-affinity IgE receptor for all allotypes and the ligation of FcγRIV by antigen-IgE immune complexes promotes macrophage-mediated phagocytosis and is involved in lung inflammation.