Importantly, signalling through A2AR regulates PBMCs function [23], and increased levels of A2AR have been found in lymphocytes from patients with immunological diseases, including systemic lupus erythematosus [24], amyotrophic lateral sclerosis [25], multiple sclerosis [26] and rheumatoid arthritis [27]. Here, ADORA2A is linked to rheumatoid arthritis.