Elevated serum complement shows promise as a potential clinically practical biomarker for disease activity in myelin oligodendrocyte glycoprotein antibody-associated disorders.

BACKGROUND

We aim to elucidate the differences in complement activation between myelin oligodendrocyte glycoprotein antibody-related disease (MOGAD) and neuromyelitis optic spectrum diseases (NMOSD), and explore the relationship between complement levels and disease activity in MOGAD.

METHODS

We retrospectively included 171 records of commonly used serum complement indicators, immunoglobulin, and systemic inflammatory markers from 96 MOGAD patients, 185 records from 97 anti - Aquaporins - 4 IgG (AQP4 - IgG) seropositive NMOSD cases, and 15 records from 11 AQP4 - IgG seronegative NMOSD cases.

RESULTS

MOGAD patients exhibited higher C3 (acute phase, p = 0.003) and C4 (acute phase, p < 0.001; whole course, p < 0.001) levels than NMOSD patients. In the MOGAD cohort, elevated CH50 levels were found in 76.47 % (130/170) cases, with higher frequencies during the acute phase 80.82 % (59/73). In the acute phase, MOGAD patients showed increased C4 (p = 0.022), CH50 (p = 0.021), and IgG (p = 0.031) levels. We also observed the dynamic fluctuations in complement concentrations after clinical attacks in MOGAD, with complement concentrations peaked during the acute phase and declined during remission (C3, 81.82 %, 9/11; C4, 63.64 %, 7/11; CH50, 72.73 %, 8/11). Positive correlations were observed between complement levels (p < 0.05) and IgG, CRP, ESR, and cerebrospinal fluid white blood cell count in MOGAD patients. Patients with higher CH50 levels tended to experience earlier recurrence than those with lower CH50 levels (log-rank p = 0.076).

CONCLUSIONS

Clinically practical complement indicators can reflect disease activity, and CH50 can serve as prognostic candidate biomarkers for relapse in MOGAD.