CD28 and rheumatoid arthritis: ➢ Loss of CD62L expression by T cells isolated from the infection or inflammation site compared to respective blood sample.➢ Shift of local CD4/CD8 ratio toward CD8 in infected and CD4 in RA patients.➢ Perforin and granzyme B expression by CD8 T cells at site of infection.➢ Detection of CD28+ and CD28− subpopulation in lavage with increased CD11b and CD57 expression on CD28− CD8 T cells.➢ Expansion and infiltration of cytotoxic CD8 effector T cells in patients with implant-associated bone infections.