AB0692 Anti-C1Q antibodies in correlation with lupus nephritis in patients treated by rituximab

Objectives The aim of the study was to assess the levels of the antibody to C1q complement component (anti-C1q) in the sera of patients (pts) with lupus nephritis (LN) in relation to the clinical activity of SLE during anti-B-cell therapy with Rituximab (RTM). Methods The study involved 41 pts with definiteSLE (3 male, 38 female; mean age Me 27,5[22-36]).The concentration of anti-C1q in the blood were determined by immunoenzyme methods. Associations between levels of anti-C1q antibodies and parameters of LN were statistically analyzed. Patients were divided into 2 groups: those with LN (n=25) and without renal involvement (n=16).Marked highly positive (>30U/ml), low positive (10-30U/ml) and negative (≤10U/ml) levels of anti-C1q. Results In pts with LN highly positive levels of anti-C1q occurred significantly more frequently than in pts without renal involvement (p=0.04). The majority of pts without LN had negative and low positive levels anti-C1q. In the group of 25 pts with nephritis in 7 were highly positive levels of anti-C1q, and in the rest of pts were found negative and low positive levels of anti-C1q. In pts without nephritis (n=16) in only one was detected highly positive anti-C1q. In patients with nephritis in a month after treatment with RTM was observed a significant decrease of levels of anti-C1q (p=0.002), which persisted through a year after treatment with RTM (p=0.006). There was no association between SLE activity index SLEDAI 2K and the level of anti-C1q before initiating therapy. Conclusions The results of recent studies suggest that there is a link between the presence of highly positive levels of anti-C1q Abs and kidney involvement in SLE. As a result of therapy with RTM revealed a significant decrease of levels of anti-C1q Abs. Disclosure of Interest None Declared