Peripheral CD4+CD28null T-cells as predictors of damage in systemic lupus erythematosus patients

OBJECTIVES: To determine whether the CD4+CD28null T-cells subpopulation predicts the occurrence of damage in SLE. METHODS: This longitudinal study was conducted in consecutive SLE patients seen every six months in our Rheumatology Department since 2012. Patients in whom CD4+CD28null T-cells had been measured and who had at least one subsequent visit were included in the study. Survival analyses (univariable and multivariable Cox-regression models) were performed to determine the risk of overall and domain damage (as per the SLICC Damage Index - SDI) as a function of the frequency of this T-cell subpopulation. The multivariable model was adjusted for pertinent confounders. All analyses were performed using SPSS 21.0. RESULTS: One hundred and nineteen patients were evaluated; their mean (SD) age was 43.5 (11.9) years, 113 (95.0%) were female. Disease duration was 7.8 (7.0) years, the SLEDAI 5.3 (4.1) and the SDI 1.0 (1.4). The percentage of CD4+CD28null T-cells was 17.4 (14.0). The mean follow-up was 2.1 (0.8) years, and the mean number of visits per patient 3.5 (1.1). Forty-six (38.7%) patients increase at least one SDI point. In the univariable and multivariable analyses, the percentage of CD4+CD28null predicted the occurrence of lung damage [HR: 1.042 (CI95%: 1.001-1.085); p=0.047 and HR: 1.099 (CI95%1.020-1.184); p=0.013, respectively] but neither the total SDI score nor all other SDI domain scores were predicted by the percentage of CD4+CD28null cells. CONCLUSIONS: In SLE patients, CD4+CD28null T-cells predict the occurrence of new lung damage, independently of other risk factors but not of overall damage or damage on other domains.