CD40 and rheumatoid arthritis: Moreover, a recent study highlighted that the PBMCs of RA patients express several M1 macrophage molecules, including class II major histocompatibility complex molecules (HLA-DR), CD64, CD86, and CCR5, while in the synovial fluid, they show a high level of HLA-DR, CD40, CD80, CD86, and CD276 [14].