Abstract
Purpose: :
Sarcoidosis is a multi-system chronic inflammatory disorder of unknown etiology. It is well known that angiotensin-converting enzyme (ACE) and lysozyme are helpful serum markers for the diagnosis of sarcoidosis. ACE is thought to be one of the most useful markers, showing high specificity for sarcoidosis, although it is not very sensitive. Surfactant protein D (SP-D) is located in epithelial cells of multiple mucosal surfaces. It is commonly used to diagnose and screen for pulmonary diseases. In the present study, serum levels of SP-D were measured in patients with uveitis to ascertain whether SP-D is a clinically useful laboratory parameter to diagnose sarcoidosis.
Methods: :
Sera were obtained from 81 patients with sarcoidosis, 16 patients with Behcet disease, 40 patients with HLA-B27 associated uveitis, 50 patients with Vogt-Koyanagi-Harada (VKH) disease, and 33 healthy volunteers. Serum SP-D levels were quantified using an SP-D EIA kit.
Results: :
The average level of serum SP-D from healthy control subjects was 39.7 ng/ml. In uveitis patients with sarcoidosis, the mean serum SP-D level was 57.0 ng/ml, and the uveitis patients with other etiologies had mean levels of 38.6 ng/ml in Behcet disease, 38.2 ng/ml in HLA-B27 associated uveitis, and 31.3 ng/ml in VKH patients. The average serum SP-D level of patients with sarcoidosis was significantly higher than those of any other etiologies of uveitis and healthy controls (p < 0.01).
Conclusions: :
Since some sarcoidosis patients suffer from damage to the lung, it is reasonable to suggest that the elevated serum levels of SP-D in sarcoidosis are due to its release by pulmonary tissues. SP-D may provide a less invasive and less expensive laboratory examination to screen for sarcoidosis. SP-D should be considered a new laboratory parameter for the diagnosis of uveitis and sarcoidosis.
Keywords: uveitis-clinical/animal model • autoimmune disease