Adaptive immune system: The arm of the immune response that encompasses lymphocyte activity and is characterised by specifi c responses to antigens, and is followed by immunological memory such that future responses to the same antigen are faster and of greater magnitude. Agonism/antagonism: LILRA3 may act as a competitive antagonist to the activating functions of LILRA2 because these receptors potentially share the same ligands. These ligands would act as agonists when binding LILRA2, thereby activating the receptor. However, upon binding soluble LILRA3 the ligands can no longer bind LILRA2 and hence there is no subsequent activation. Disease-modifying anti-rheumatic drugs (DMARDs): Drugs used in the therapy of RA that may reduce disease severity and progression. Immunoreceptor tyrosine-based activation motif (ITAM): The intracellular motif of certain membrane proteins that propagates the activating signals of many different cell-surface receptors, including activating LILRs. The critical amino acid residue in this signaling motif is tyrosine, which serves as the site of recruitment of intracellular molecules involved in transducing positive cellular signals, such as protein tyrosine kinases.