Table 1.
Clinical PD-1 phenotypes identified in SLE.
| Cell type | Patients | Source | PD-1 marker |
|---|---|---|---|
| Neutrophils [9] (CD15+CD3−) | Chinese patients diagnosed according to the revised criteria for SLE from the American College of Rheumatology (ACR) 1997 | Whole blood | PD-L1hi is compared to healthy controls, correlated with the SLEDAI score, and can be reduced with immunosuppressive drugs |
| DCs (CD14lo) and monocytes (CD14hi) [75] | U.S. pediatric patients diagnosed according to ACR 1997 | Peripheral blood mononuclear cells | PD-L1reduced is compared to healthy controls |
| Mucosal-Associated Invariant T (MAIT) cells [84] (CD3+TCRγδ−Vα7.2+CD161high) | Korean SLE patients diagnosed according to ACR 1997 | (PBMC) | PD-1elevated is identified on MAIT cells that are reduced in percentages compared to healthy controls |
| CD4 T follicular helper (Tfh) [85] (CD4+CXCR5+) | Chinese SLE patients diagnosed according to ACR 1997 | PBMC | PD-1+ Tfh cell expansion is positively associated with SLEDAI score and B regulatory cell (CD19+CD5+CD1dhigh) expansion |
| CD4 Tfh cell [86] (CXCR5+/−CXCR3−) | Chinese SLE patients diagnosed according to ACR 1997 | PBMC | PD-1+ Tfh cell percentages are positively associated with SLEDAI score |
| CD4 T cell [87] (CD25+) | Icelandic and Swedish patients with at least 4 of ACR 1982 classification criteria for SLE | PBMC | PD-1reduced is compared to controls and associated with PD-1.3A polymorphism |
| CD8 T cell [88] (IL-7 receptorlo) | United Kingdom SLE patients presenting with untreated, active (at least 4 ACR 1982 criteria) disease | Anti-CD3/anti-CD28 treated PBMCs | PD-1reduced is compared to PD-1 on characterized “exhausted” CD8 T cells highlighting a defect in these cells that is also linked to poor SLE patient outcomes |
| B cell [89] (IgG antibodies) | Chinese SLE patients diagnosed according to ACR 1997 | PBMC | Anti-PD-1 antibodies are elevated and positively associated with SLEDAI score |
| B cell [90] (CD11chi T-bet+ CD27lo CD38lo) | U.S. SLE patients | Sera | PD-1 and PD-L1 transcripts are elevated compared to healthy controls and the frequency of these cells is associated with SLEDAI score |
| DN2 effector B cell [91] (CD27− IgD− CXCR5−CD11c+T-bet+) | U.S. African American SLE patients diagnosed according to ACR 1997 | PBMC | PD-1 transcripts are elevated compared to healthy controls and the frequency of these cells is associated with SLEDAI scor |
| Unknown [92] | Chinese SLE patients | Sera | Soluble PD-L1 is elevated compared to healthy controls |