CD4 and rheumatoid arthritis: The results showed that the percentages of activated T cells (CD4+CD69+, CD4+CD154+; P < 0.05) were increased and the percentage of unactivated T cells (CD4+CD62L+; P < 0.05) was decreased after co-cultured with IgD (10 μg/ml) or PHA (4 μg/ml) for 24h in RA patients.