Utility of lyophilized PMA and ionomycin to stimulate lymphocytes in whole blood for immunological assays.
BACKGROUND
The need to implement robust biomarkers in clinical trials has never been greater, and such efforts can be easily compromised by reagent instability or simple human error during assay set-up. Many biotechnology and pharmaceutical companies are introducing efforts to conduct biomarker studies under more rigorous settings, and the use of plates or tubes pre-loaded with stimulation or staining reagents could be of value for studies that involve flow cytometry.


METHODS
Five reagents lyophilized from ethanol or CHAPS buffer stock solution of phorbol 12-myristate 13-acetate (PMA) and ionomycin were benchmarked against standard DMSO liquid formulation for their stimulation equivalency. The median fluorescence intensity of phosphorylated ribosomal protein S6 in lymphocytes was assessed on a BD FACSCalibur.


RESULTS
We demonstrate here that tubes pre-loaded with lyophilized versions of the liquid reagents can provide equivalent stimulation in healthy volunteer specimens.


CONCLUSIONS
The value of this approach is that it safeguards against omission or erroneous addition of bulk liquid formulations of PMA and ionomycin to the reaction vessel (i.e., plate or tube) and also lends itself to extended stability/shelf-life of these reagents. On the basis of this initial success, we plan to expand our evaluation of lyophilized reagents so that they can be incorporated into our clinical biomarker campaigns as appropriate.
Department of Medical Sciences, Amgen Inc., Thousand Oaks, California, USA.
Shelley Sims
SS
Belouski
Julie
J
Wilkinson
John
J
Thomas
Keith
K
Kelley
Shen-Wu
SW
Wang
Sid
S
Suggs
John
J
Ferbas
D015415:Biomarkers / Q000032:analysis; D001772:Blood Cell Count; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007118:Immunoassay / Q000379:methods; D015759:Ionomycin / Q000494:pharmacology*; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000737:chemistry / Q000166:cytology* / Q000187:drug effects*; D038601:Ribosomal Protein S6 / Q000032:analysis*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D015415:Biomarkers; D038601:Ribosomal Protein S6; D015759:Ionomycin; D013755:Tetradecanoylphorbol Acetate; D004121:Dimethyl Sulfoxide