CD14 was expressed on 13.3 ± 20.4% of CD4+CD28null T cells versus 0.7 ± 1% of CD4+CD28+ T cells in AS, on 8.8 ± 15.7% of CD4+CD28null T cells versus 1.0 ± 2.3% of CD4+CD28+ T cells in PsA, and on 11.3 ± 17.2% of CD4+CD28null T cells versus 0.6 ± 0.6% of CD4+CD28+ T cells in RA (each with P < 0.001). This evidence concerns the gene CD28 and rheumatoid arthritis.