The function of FCER2 (Fc epsilon receptor II, ENSG00000104921) is as follows. Low-affinity receptor for immunoglobulin E (IgE) and CR2/CD21. Has essential roles in the regulation of IgE production and in the differentiation of B cells. On B cells, initiates IgE-dependent antigen uptake and presentation to T cells (PubMed:2167225). On macrophages, upon IgE binding and antigen cross-linking induces intracellular killing of parasites through activation of L-Arginine- nitric oxide pathway (PubMed:7544003). {ECO:0000269|PubMed:2167225, ECO:0000269|PubMed:7544003}.