Cyto-Chex® Blood Collection Tube Stabilizes Samples Stored At Elevated Temperatures For Flow Cytometry Analysis

Abstract
We have previously demonstrated that Streck Cyto-Chex® Blood Collection Tube (BCT) preserves whole blood specimens for HIV testing by flow cytometric analysis for seven days at room temperature. Increased stability reduces the need for weekend staffing and shipping delays are not likely to require patient redraws. However, in resource poor settings sample storage, transportation time, and temperature are not reliable. The effect of elevated temperatures on stabilized blood specimens collected in Cyto-Chex BCT has not been tested. Here, we report that Cyto-Chex BCT is capable of maintaining the integrity of CD markers critical for HIV assessment at temperatures up to 37°C for three days. Whole blood samples were drawn from 25 healthy donors into K2EDTA tubes and Cyto-Chex BCT. Flow cytometric analysis was performed on samples collected and stored at 30°C or 37°C for 6 hours, 3 days, or 7 days. Cell counts for CD3, CD4, and CD8 were determined for each sample at each time point and compared to 6 hour K2EDTA samples. While K2EDTA samples fail at elevated temperatures, Cyto-Chex BCT stabilizes all three markers for seven days at 30°C. Additionally, CD3 and CD4 are stable at 37°C for 72 hours. Cyto-Chex BCT can increase the reliability of CD4 testing in resource poor areas. Monitoring CD4 counts in HIV patients is an extremely important tool enabling physicians to modulate treatment accordingly. Streck Cyto-Chex BCT stabilizes whole blood samples at elevated temperatures for extended periods of time, thereby improving the reliability of HIV monitoring.