Introduction:
Ocular involvement is quite common in Behçet’s disease (BD) and may cause crucial functional complications. Even though the mechanisms of BD remain unclear, advances in gene­tic and immunological fields have improved our understanding of the immunopathogenesis of BD ocular involvement. Little is known about the expression of a proliferation-inducing ligand (APRIL) in terms of ocular involvement in BD. The objective of this study was to determine whether serum APRIL concentrations are associated with ocular involvement in patients with BD.

Material and methods:
The study included 60 patients diagnosed with BD matched by age and sex to 30 healthy individuals. Every patient underwent a clinical evaluation, and the Behçet’s Disease Current Activity Form (BDCAF) was utilized to quantify disease activity. All patients underwent a comprehensive ophthalmological assessment. Serum APRIL was assessed for patients as well as controls.

Results:
One or more ocular manifestations were found in 42 BD patients (70%), while 18 patients (30%) had no ocular involvement. The mean level of serum APRIL levels was markedly elevated in BD patients, particularly those with ocular involvement, compared to both BD patients without ocular involvement and healthy individuals. A statistically significant association was determined between high APRIL concentration and development of uveitis, cataract, and hypopyon. Cutaneous lesions and arthritis were strong independent predictors for ocular involvement in BD patients.

Conclusions:
Overexpression of APRIL in patients with BD, particularly in terms of uveitis, cataract, and hypopyon, lends credence to the idea that B cell activating factors have an important function in BD. These findings may indicate that serum APRIL concentrations can differentiate a clinical subgroup of BD patients with ocular disease. As a result, finding a new therapeutic strategy targeting the APRIL pathway might be beneficial in BD patients suffering from ocular involvement.