CD4 and rheumatoid arthritis: The number of IFN-γ-producing cells was higher in the CD8-positive compared with the CD4-positive population (HDs: 6.6% ± 1.1% CD4/IFN-γ-positive cells and 14.6% ± 2.2% CD8/IFN-γ-positive cells, p < 0.02; patients with RA: 2.7 ± 0.3 CD4/IFN-γ-positive cells and 6.2 ± 0.4 CD8/IFN-γ-positive cells, p < 0.001).