CD28 and systemic lupus erythematosus: All the subtypes tested, including CD4+CD45RA+CD28+, CD4+CD45RA+CD57−, CD4+CD45RA-CD57−, CD4+CD28+CD57−, CD4+CD28+CD57+, CD4+CM, CD8+CD31+, CD8+Naive, CD8+CD45RA-CD57−, CD8+CD28+CD57−, and CD8+CD28+CD57+, correlated with DN B cells in SLE patients tested.