Objective: To evaluate the use of non-invasive estimation of CP-1 in urine as a good indicator for lupus nephritis activity.

Methods: The study was conducted on 30 patients with systemic lupus erythematosus (SLE) (group I): 15 of these patients were selected without renal involvement (group I [A]), and the other 15 were selected with evidence of renal involvement (group I [B]). Further 10 age- and sex-matched healthy subjects were taken as a control group (group II). The SLE disease activity index (SLEDAI) was applied. Laboratory investigations done for the studied group of patients included: renal function tests (antinuclear antibody) titer, (anti-double-stranded DNA) titer, and monocyte chemotactic protein 1 (MCP-1) level in serum and urine samples.

Results: Serum MCP-1 was significantly higher in SLE patients with nephritis than in the control group, while no significant difference was found between SLE patients without nephritis and the control group. Urinary MCP-1 in patients with active lupus nephritis (LN) were significantly higher than both patients with inactive LN and control the group. Urinary MCP-1 in SLE patients with nephritis was significantly higher than both group I (A) and group II. Urinary MCP-1 correlated positively with proteinuria, and negatively with creatinine clearance and hemoglobin; thus, urinary MCP-1 correlates with the severity of nephritis.

Conclusions: Urinary and not serum MCP-1 is a useful invasive technique for the assessment of renal disease activity in patients with LN.