[Significance of Detecting Serum Complement C3 and C4 in Patients with Multiple Myeloma]

To investigate the significance of detecting serum complement C3 and C4 in patients with multiple myeloma (MM) and to explore its correlation with myeloma bone disease (MBD).

The levels of serum complement C3 and C4 in 69 MM patients and 30 healthy people were examined by scatter nephelometry. The bone density of L1-4 vertebral body, bilateral femoral neck and bilateral hip joints were measured by dual energy bone density meter (DXA).

The levels of serum complement C3 and C4 in MM patients significantly increased in comparison with that in healthy people (P＜0.01). The patients in advanced clinical stage exhibited a higher levels of C3 and C4 than those in stable stage (P＜0.01). In addition, the patients with grade C of MBD had a higher levels of serum complement C3 and C4 than those in patients with grade A and B of MBD (P＜0.01). The levels of serum complement C3 and C4 in MM patients negatively correlated with bone density in L1-4 vertebral body, bilateral femoral necks and hip joints. The correlation coefficients were r=-0.938, r=-0.659, r=-0.745, r=-0.748, r=-0.596 in complement C3 and r=-0.908, r=-0.623, r=-0.710, r=-0.714, r=-0.595 in complement C4, respectively.

The levels of complement C3 and C4 positively correlate with the severity of bone disease and bone density in MM patients, which suggests that complement C3 and C4 plays important roles in the development of MBD. The levels of serum C3 and C4 may be the sensitive biomarkers of MBD.