C3 and amyotrophic lateral sclerosis: Therefore, we measured the mRNA levels of key components of the classical/lectin pathway (C1qB and C4), alternative pathway (fB), the central component to all pathways (C3) and the complement regulators (CD55 and CD59a) in the lumbar spinal cord of NTg, TDP-43WT and TDP-43Q331K mice using quantitative real-time PCR during disease progression of ALS (3, 10 and 16 months).