DAP and systemic lupus erythematosus: On the other hand, expression of HLA-DPB1, CD8, a regulator of T lymphocyte activation, and molecules expressed in activated B cells such as FCRLA (Fc Receptor Like A) were significantly upregulated in SLE patients with the DAP1 risk allele in comparison to SLE patients with the protective allele (Fig. 4e, f).