Immunology / Flow Cytometry
In 1991, Streck used the technology it had developed for stabilizing white blood cells to develop a control for immunophenotyping by flow cytometry. The first control, CD-Chex, offered only white blood cells. These cells were stabilized in a way that the antigen sites were preserved and not destroyed by the fixative.

In 1995, Streck introduced an improved version of the control that included red blood cells. The control, CD-Chex Plus, closely resembled a patient sample as it was tested by flow cytometry.

As immunophenotyping by flow cytometry moved from the research laboratory to the clinical laboratory, the need for controls grew. In 1995, Streck introduced Cyto-Chex, which allowed customers to dilute a patient sample of whole blood 1:1. This sample could be stored up to seven days for testing by flow cytometry.

In 2004 Streck introduced Cyto-Chex BCT, a direct-draw vacuum blood collection tube that contains a preservative reagent. Cyto-Chex BCT preserves the integrity of white blood cells at room temperature three times longer than traditional methods, thus allowing for more cost-effective, reliable and safer testing of patient samples for immune system diseases.