CD80 and rheumatoid arthritis: When the expressions of CD80 and CD86 were compared among three different monocyte subsets in RA patients, CD80 expression was significantly higher in CD14+CD16+ monocytes in synovial fluid (Fig. 3D, p<0.01), whereas CD86 expression was markedly lower in synovial CD14dimCD16+ (Fig. 3E, p<0.05).