Accuracy Evaluation of the BD FACS Presto System

The enumeration of T lymphocytes positive for the CD4 antigen is used to determine the immune status of patients with, or suspected of developing, immune deficiencies such as AIDS. The BD FACS Presto™ is an investigational automated system for in vitro diagnostic use in performing the direct enumeration of CD4 absolute count, CD4 percentage of lymphocytes, and hemoglobin (Hb) concentration in human whole blood. This is a prospective study to determine the relative bias between the investigational BD FACS Presto system and the predicate BD FACS Calibur with BD Tritest system in their determination of absolute CD4, % CD4, and Hb concentrations.