Belonging to the Fc receptor-like family, studies demonstrate that FCRL4 is mainly expressed in memory B cells in sub-epithelial regions, and the presence of the receptor is associated with viral infections (e.g. HIV) and autoimmune diseases (e.g. rheumatoid arthritis), yet authors demonstrate that other cellular stages might express this receptor, including plasma cells88,89. This evidence concerns the gene FCRL4 and rheumatoid arthritis.