COMPLEMENT FACTORS C3, C4 AND C5A IN MYASTHENIA GRAVIS: LOOKING FOR A POTENTIAL DISEASE ACTIVITY MARKER.

MANUELLI, PAULA; JUSTO, MARIANO; MANIN, ANALISA; FERNANDEZ, VICTORIA; AGUIRRE, FLORENCIA; VILLA, ANDRES; GONZALEZ MAGLIO, DANIEL; LEONI, JULIANA; PAZ, MARIELA LAURA

Congreso; Reunión Conjunta de Sociedades de Biociencias.; 2017

Myasthenia Gravis (MG) is an autoantibody-mediated pathology. Many of these autoantibodies bind to the acetylcholine receptor in the neuromuscular junction, activating the complement system, thus generating damage and muscle weakness. We aimed to measure C3, C4 and C5a concentration in MG patients, and to analyze their potential as disease activity markers. We collected 63 samples from MG diagnosed patients (17 exacerbated) and normal matching controls (nc). There were 11 cases of paired samples. Disease status (remission: rem or exacerbation: ex) was determined by neurologic evaluation. We quantified C5a using a home-setup ELISA (expecting increases). C3 and C4 were measured with commercial radial immunodifussion plates (expecting decreases). There were no statistically significant (ss) differences in C3 and C4 mean values between groups (rem, ex, nc). But there was a ss correlation between C3 and C4 values in the 63 samples. This correlation was strong (r2=0.9) in the group of patients in an ex period (p<0.0001). Among all MG patients, 10/17 (59%) showed high C5a values during an experiod. On the other hand, 27/46 (59%) showed low C5a values during a rem period (vs. mean value of nc). There was a ss increment in C5a values (p<0.05) in the ex group vs. nc, when analyzing the group of 11 paired samples. We couldn?t find a ss mean difference or correlation when analyzing paired samples themselves. In conclusion, C3 and C4 were not good markers at differentiating disease status in MG patients, mainly due to the wide range of normal values they have. Alternatively, these two values have a very good correlation in ex MG patients, indicating that the two factors are being consumed simultaneously due to complement system activation by autoantibodies. The increment in C5a values in ex MG patients seems to be a promising disease activity marker, however, more patients need to be evaluated in order to achieve ss differences.