Senescent CD4+CD28null cells are increased in chronic hyperuricemia, show aberrant effector phenotypes, and are reversed after allopurinol therapy: a proof-of-concept pilot study.

To characterize CD4+CD28null cells in chronic hyperuricemia and investigate whether allopurinol could restore CD28 expression and the balance of T helper phenotypes. Asymptomatic individuals with chronic hyperuricemia and ultrasonographic findings evocative of urate deposition in the joints. Age- and gender-matched normouricemic individuals were also studied. Oral allopurinol at 150 mg/day for 4 weeks, followed by 300 mg/day through week 12. Color-flow cytometry on peripheral blood mononuclear cells (PBMC) with antibodies against CD4, CD28, T-bet (Th1), GATA-3 (Th2), and RORγt (Th17). Six patients (five men, median age of 53 years) and seven controls were studied. At baseline, hyperuricemic patients had more CD4+CD28null/CD4+ cells than normouricemic subjects (36.8% vs. 6.1%; p = 0.001), with a predominance of T-bet+ cells (98.5% vs. 6.6%; p = 0.001) and few RORγt+ cells (0.7% vs. 89.4%; p = 0.014). In hyperuricemic patients, the number of CD4+ cells/10,000 PBMC was similar before and after allopurinol (3378 vs. 3954; p = 0.843). Conversely, CD4+CD28null cells decreased from 36.8% (23.0-43.7) to 15.8% (4.7-28.1; p = 0.031). CD4+CD28nullT-bet+ cells decreased from 98.5% (95.0-99.4) to 88.3% (75.2-98.9; p = 0.062), CD4+CD28nullGATA-3+ cells increased from 0% (0-4.0) to 2.8% (0.1-15.6; p = 0.156), and CD4+CD28nullRORγt+ cells increased from 0.7% (0.4-7.0) to 4.5% (1.3-28.1; p = 0.031). The CD4+CD28null cell subset is abnormally expanded in chronic hyperuricemia, despite the absence of overt urate-related disease. Allopurinol may partially restore CD28 expression on CD4+ cells while enhancing the homeostatic balance of T helper phenotypes. ClinicalTrials.gov, number NCT04012294.

Performance analysis of Luminex and ELISA to profile serum IP-10 as a biomarker in systemic lupus erythematosus.

OBJECTIVE: Interferon-γ inducible protein-10 (IP-10) is a promising biomarker in systemic lupus erythematosus (SLE). The optimal quantification platform has not yet been identified. We compared the performance of bead-based multiplex assay (Luminex) and high-sensitivity enzyme-linked immunosorbent assay (hs-ELISA) for profiling serum IP-10 as a biomarker of lupus activity. METHODS: A cross-sectional study was conducted on outpatients with SLE. Serum IP-10 was measured simultaneously on Luminex and hs-ELISA, and correlation between platforms was assessed. Additionally, IP-10 levels were tested against disease activity and organ involvement. RESULTS: One-hundred and forty-one patients (88% women; 38 years old) were studied. Median IP-10 levels were 100.9 (125.2) pg/mL by Luminex and 156.5 (191.7) pg/mL by hs-ELISA. Correlation analysis showed Spearman's ρ = 0.621 (p < 0.0001) between Luminex and hs-ELISA. Quantification of IP-10 by Luminex showed a significant correlation (ρ = 0.198; p = 0.021) with disease activity, while this was not observed (ρ = 0.036; p = 0.683) when measured using hs-ELISA. Serum IP-10 levels were lower in quiescent patients than in those with active disease (70.8 [68.4] versus 114.3 [123.9] pg/mL; p = 0.024), with an AUC-ROC = 0.62 (p = 0.029), sensitivity = 47.9%, specificity = 77.5%, and positive likelihood ratio = 2.1. Patients with active arthritis had higher IP-10 levels than non-arthritis patients (158.1 [505.4] versus 94.1 [114.0] pg/mL; p = 0.008), with an AUC-ROC = 0.73 (p = 0.0009), sensitivity = 72.7%, specificity = 66.4%, and positive likelihood ratio = 2.1. No other type of organ involvement was identified by serum IP-10. CONCLUSIONS: Luminex performs better than hs-ELISA as a quantification platform for IP-10 as it correlates with disease activity and identifies active arthritis in SLE.