SLAMF1 and systemic lupus erythematosus: Furthermore, we isolated CD27-IgD- and CD27+IgD- B cells from 3 patients with SLE and found the same trend for expression of CD83, ICOSL, SLAMF1, and IL-21R (results not shown), suggesting that our in vitro generated CD27-IgD- and CD27+IgD- B cells mimic the B cells seen in SLE.