The family of β2 (CD18) integrins (comprising LFA-1 (CD11a/CD18), complement receptor 3 (CD11b/CD18 or Mac-1), complement receptor 4 (CD11c/CD18 or p150,95), and CD11d/CD18) is central in the inflammatory response and in RA. This evidence concerns the gene ITGAL and rheumatoid arthritis.