The effect of methotrexate on improving serological abnormalities of patients with systemic lupus erythematosus.

Objective: This was an open-labeled, prospective, control study to determine the efficacy of methotrexate (MTX) for improving serological abnormalities in patients with systemic lupus erythematosus (SLE).
Methods: Thirty patients with a low serum complement and/or high anti-double-stranded DNA (dsDNA) antibody levels during a prednisolone taper received MTX orally at a dose of 7.5 mg/week over 12-18 months (MTX group). Eighteen SLE patients were selected as controls (control group). At the time of entrance into the study, all patients were receiving <15 mg/day of prednisolone. The C3, C4, and immunoglobulin (Ig)G, IgA, and IgM levels were measured using a turbidimetric immunoassay. The anti-dsDNA antibody level was measured using the Farr assay.
Results: Significant increases in C3 and C4 levels and significant decreases in anti-dsDNA antibody, IgG, IgA, and IgM levels from baseline were observed for 3-18 months after the trial in the MTX group but not in the control group. At the end of the study, C3 and/or C4 levels in 96.7% of the MTX patients and 33.3% of the control patients were normalized or elevated (p = 0.0001), and anti-dsDNA antibody levels were normalized or lowered in 24 of the 26 MTX patients (92.3%) and in 50.0% of the control patients (p = 0.0022). In addition, a significant reduction in SLE Disease Activity Index (SLEDAI) score and a prednisolone-sparing effect were observed for the MTX group but not the control group. A significant increase in mean corpuscular volume of red blood cells, which is indicative of an anti-folic-acid metabolic disorder induced by MTX, was observed only for patients in the MTX group. Five patients (16.7%) discontinued MTX treatment because of disease flare, and another three (10.0%) discontinued due to treatment side effects.
Conclusion: MTX appears to be effective for improving serological abnormalities frequently observed before disease flares in SLE patients on a prednisolone taper.