Quality control of immunocytologic testing. Prolonged preservation of cell surface antigen reactivity with magnesium...

A sucrose-magnesium chloride-glycerol storage solution (sucrose-magnesium chloride) can preserve antigenicity of cytologic preparations for prolonged periods of time. This storage method was evaluated relative to our immunocytologic technology with the specific aim of exploring its use as a quality control measure. Neuroblastoma and leukemia cell lines, patient bone marrow, and blood specimens were serially tested during a 15-week period to evaluate preservation of immunoreactivity and cell morphological features. Slides that had been air dried and stored at 4 degrees C were compared with those that had been fixed with methanol and paraformaldehyde and stored in sucrose-magnesium chloride at -20 degrees C. The sucrose-magnesium chloride method proved to be superior, and antigen-antibody binding and cell morphology were preserved even after 15 weeks of storage. This method, now in use as a quality control measure in our laboratory, constitutes a practical assurance program for immunocytologic analysis.