After 72 h of co-culture, there were no differences in the percentages of T lymphocytes with bound PLTs regardless of the origin of PBMCs and PLTs (% CD4+ PLT+ in HD PBMCs: 14.84 ± 1.93 for HD PLTs vs. 15.94 ± 2.1 for RA PLTs; RA PBMCs: 14.27 ± 1.93 for HD PLTs vs. 16.72 ± 2.39 for RA PLTs). This evidence concerns the gene CD4 and rheumatoid arthritis.