Poor Resolution of Dim Markers Masked by Autofluorescence
Symptom
Low-expression markers become indistinguishable from background. Positive and negative populations show poor separation, with dim fluorophores completely masked by cellular autofluorescence.
Common Causes
1Dim fluorophores (low-brightness dyes) easily masked by autofluorescence signal
2FITC highly susceptible due to overlap with NADH and flavin emissions
3UV (355 nm) and blue (488 nm) lasers induce strongest autofluorescence affecting FITC and BUV dyes
4Low-expression antigens generating weak signal compared to background
Solutions
1Assign bright dyes (PE, BV421) to low-expression markers instead of FITC
2Avoid FITC for critical markers; use dyes with emissions outside autofluorescence range
3Use red/far-red lasers (633 nm and beyond) which are least affected by autofluorescence
4Include FMO (Fluorescence Minus One) controls to distinguish true signal from background
5Consider spectral unmixing to separate dim marker signal from autofluorescence