Activation of serum complement system is involved in the pathological process of uveitis and open angle glaucoma.Pathogenesis and pathological characteristics of Posner-Schlossman syndrome (PSS) are similar to uveitis and open angle glaucoma.However, etiology of PSS remains unelucidated.The activation complement in PSS patients’ serum is rarely reported.

The aim of this study was to investigate the activation of serum complement in PSS patients for PSS pathogenesis.

A prospective case-controlled study was designed.The peripheral blood simples of 79 PSS patients were collected from Shenzhen Eye Hospital during December 2013 to December 2015, and the peripheral blood simples were obtained from 83 unrelated healthy blood donors as healthy control group.Immuno-scatter turbidmetry was adopted to detect the common activated components in complement pathway in each group including complement C3 (a vital intersection molecule in the three pathways), C4 (the vital molecule both the complement classical and lectin pathways), split products C3a, soluble membrane attack complex (sC5b-9), C1q (complement classical pathway), L-ficolin (complement lectin pathway), complement factor Bb (complement alternative pathway), IgG, IgA and IgM.The correlation between serum C3a content and sC5b-9 content in PSS group was analyzed.The serum contents of fabric binding protein 2 (FCN2) (a marker of serum classical pathway), factor Bb (a marker of complement alternative pathway), C3a (the common activation products of three complement activation pathways), and sC5b-9 were assayed by ELISA.This research protocal was approved by Shenzhen Eye Hospital and written informed consent was obtained from each PSS patient prior to any medical examination.

Compared with normal control group, the serum levels of C3, C4, C3a, sC5b-9, C1q, FCN2, IgG, IgA and IgM were significantly higher in PSS group (Z=-4.743, -2.913, -1.985, -2.620, -2.062, -2.500, -7.010, -6.327, -3.652, all at P<0.05). The serum complement factor Bb level was 13.87 (9.24, 32.00)μg/ml in PSS group, which was significantly lower than 20.51 (12.90, 33.50)μg/ml in normal control group (Z=-2.515, P=0.012). Serum C3a content was positively correlated with the serum sC5b-9 content in PSS group (r_s=0.832, P<0.001).

The serum complement system is activated in PSS patients.Complement alternative pathway, classical pathway and lectin pathway might all be involved in the activative process of complement system.

Glaucoma, open-angle; Syndrome; Iridocyclitis; Complement activation/ physiology; Complement pathway, activation /physiology