Objectives. The study was conducted to determine the correlation of ICAM-1, VCAM-1, and anti-C1q antibody levels with SLE disease activity index (SLEDAI) and standard SLE disease activity immunological markers (anti-dsDNA and sera C3 and C4). Study Design. This was a cross-sectional study. Materials and Methods. Blood samples were obtained from 95 SLE patients (45 active SLE and 50 nonactive SLE) and 50 controls. The subjects were assessed using SLEDAI and score of more than five is determined as having active SLE. The sera were tested for serum ICAM-1, VCAM-1, and anti-C1q (ELISA), anti-dsDNA (CLIFT), serum C3, and serum C4 (immunonephelometry). Results. Anti-dsDNA and anti-C1q antibody showed good positive correlations with SLEDAI (r = 0.529, P < 0.001 and r = 0.559, P < 0.001, resp.). VCAM-1 and sera C3 and C4 showed fair correlation with SLEDAI (r = 0.294, P = 0.004; r = -0.312, P = 0.002; and r = -0.382, P < 0.001, resp.). ICAM-1 level showed no significant correlation with SLEDAI (P = 0.062). There were significant correlations of VCAM-1 and anti-C1q antibody with anti-dsDNA (r = 0.226, P = 0.006 and r = 0.511, P < 0.001, resp.). VCAM-1 showed poor inverse correlation with serum C3 (r = -0.183, P = 0.028) and fair inverse correlation with serum C4 (r = -0.251, P = 0.002). Anti-C1q antibody demonstrated fair inverse correlation with both sera C3 and C4 (r = -0.420, P ≤ 0.001 and r = -0.398, P < 0.001, resp.). However, ICAM-1 showed no significant correlation with anti-dsDNA and sera C3 and C4 (P = 0.259, P = 0.626 and P = 0.338, resp.). Conclusions. The serum levels of anti-C1q antibody in SLE patients showed the best correlation with the SLEDAI and standard immunological tests for SLE disease activity. These data support that anti-C1q antibody is a useful marker for monitoring SLE global disease activity. The potential of VCAM-1 needs further confirmation.
Study site: Hospital Universiti Sains Malaysia (HUSM), Kubang Kerian, and Hospital Raja Perempuan Zainab II (HRPZ II), Kota Bharu, Kelantan, Malaysia
BACKGROUND: Detecting the active state of systemic lupus erythematosus (SLE) is important but challenging. This study aimed to determine the diagnostic accuracy of serum endothelial cell adhesion molecules (ICAM-1 and VCAM-1) and anti-C1q antibody in discriminating between active and non-active SLE.
METHODS: Using SELENA-SLE disease activity index (SLEDAI), 95 SLE patients (45 active and 50 non-active) were assessed. A score above five was considered indicative of active SLE. The blood samples were tested for serum ICAM-1, VCAM-1 and anti-C1q antibody using enzyme-linked immunosorbent assay (ELISA).
RESULTS: The levels of serum VCAM-1 and anti-C1q antibody were significantly higher in active SLE patients. Both VCAM-1 and anti-C1q were able to discriminate between active and non-active SLE (p-value < 0.001 and 0.005, respectively). From the receiver operating characteristic curves (ROCs) constructed, the optimal cut-off values for VCAM-1 and anti-C1q antibody in discriminating between active and non-active SLE were 30.5 ng/mL (69.0% sensitivity, 60.0% specificity, PPV 58.5%, NPV 66.7%) and 7.86 U/mL (75.6% sensitivity, 80% specificity, PPV 77.3%, NPV 78.4%), respectively. However, serum ICAM-1 level was unable to discriminate between the two groups (p-value = 0.193).
CONCLUSION: Anti-C1q antibody demonstrated the best diagnostic accuracy in discriminating between active and non-active SLE patients.
KEYWORDS: anti-C1q antibody; cell adhesion molecules; intercellular adhesion molecule-1 (ICAM-1); systemic lupus erythematosus; vascular cell adhesion molecule-1 (VCAM-1)