CD4 and rheumatoid arthritis: CCR1 (C-C motif chemokine receptor 1) is expressed in a variety of immune cell types like monocytes, CD4+ T cells, CD8+ T cells, basophils, B cells, eosinophils, neutrophils, natural killer cells, mast cells and dendritic cells and associated with a numerous diseases like multiple sclerosis, rheumatoid arthritis, chronic obstructive pulmonary disease, organ transplantation, Alzheimer’s disease, atherosclerosis and cancer [43].