High Background Signal from Autofluorescent Cell Types (Flow Cytometry (Autofluorescence))

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Accepted Answer

Elevated background fluorescence intensity across multiple channels, particularly affecting green (FITC) and orange (PE) channels. Difficult to distinguish specific antibody staining from background noise. Common causes: 1) Monocytes and macrophages rich in granules and metabolic cofactors (NADH, flavins) 2) Dendritic cells with high metabolic activity and granularity 3) Activated cells showing increased autofluorescence due to metabolic changes 4) Intrinsic cellular components (NADH, flavins, porphyrins) emitting fluorescence when excited 5) Cellular structures including mitochondria and granules contributing to background Solutions: 1) Use far-red dyes (APC, Alexa Fluor 700) for critical markers to avoid autofluorescence range 2) Include unstained controls to identify autofluorescence baseline 3) Implement spectral flow cytometry with spectral unmixing to model and subtract autofluorescence 4) Assign bright dyes (PE, BV421) to low-expression markers instead of dim fluorophores 5) Gate using additional markers to confirm population identity when autofluorescence complicates analysis