An excellent discussion of antibody titration by John Altman (Emory Vaccine Center) may be found here.
In addition, we suggest a plot of signal/noise:
Titer is affected by:
–Staining volume (e.g., 100 ul)
–Number of cells (not critical up to ~5 million cells)
–Staining time and temperature (e.g., 30 min RT)
–Type of sample (whole blood, PBMC, etc.)
(Holden Maecker, Flow Cytometry Consulting)