Exposure to Alzheimer's disease serum increased microglial phagocytic uptake of pH-sensitive fluorescent particles and downregulated expression of the lysosomal master regulator transcription factor EB ( TFEB ) and of ATPase H + transporting lysosomal V1 subunit B2 ( ATP6V1B2 ), a component of the vacuolar ATPase. Here, TFEB is linked to Alzheimer disease.