Influencing factors of serum complement C3、C4 in children with myasthenia gravis

Objective Complement plays an important role in the pathogenesis of myasthenia gravis.The formation of membrane attck complex and the damage of neuromuscular junction are inseparable from the activation of complement.Then to investigate the influencing factors of serum complement C3, C4 in children with myasthenia gravis and investigate the degree of influence of related factors. Methods One hundred sixty seven cases of hospitalized or outpatient myasthenia gravis children from the Department of Neurology in Hunan Children′s Hospital were collected, including 33 cases of general MG, 134 cases of ocular MG, and 36 cases of normal children as control group.The concentrations of serum C3, C4, IgG, IgM, IgA, IgE were detected by immune compare turbid.The influencing factors of complement C3, C4 were investigated and compared. Results The serum C3 levels were 1.07±0.22 g/L, and the serum C4 levels were(0.17±0.05)g/L in the general MG.The serum C3 levels were(1.01±0.20)g/L, the serum C4 levels were(0.20±0.08)g/L in the ocular MG.There were(1.36±0.28)g/L for C3 levels, (0.25±0.11)g/L for C4 levels in the control group.Compared with the control group, there were significant difference in C3 and C4 between the general MG and ocular MG(P<0.01 or 0.05). The partial correlations coefficients of C3 and course of disease, IgG and C3, C3 and C4 were-0.162, 0.135, 0.446(P<0.01 or 0.05). The multiple linear regression equations were as followed: C4=0.420×C3, C3=0.655+ 1.148×C4+ 0.008×body weight -0.005×course of disease.Using univaruate analysis, the effect factors of C4(F=18.151, P=0.000), body weight(F=6.420, P=0.003), course of disease(F=3.015, P=0.039), age× course of disease×body weight(F=2.997, P=0.042)to C3 were significant(P<0.05, or P<0.01). Conclusion The C3 levels are mainly affected by C4, body weight, duration and some interaction effects among several impact factors in children with MG.C4 is mainly affected by C3. Key words: Children; Myasthenia gravis; Humoral immunity; Complement 3; Complement 4