Evaluation of a new whole blood cytometric lymphocyte transformation test for immunological screening.

Lymphocyte transformation test (LTT) is usually performed by 3H-thymidine (3H-TdR) incorporation of phytohemagglutinin stimulated lymphocytes. This test presents a lack of standardization as well as a great variability of results making it difficult to compare the results carried out by different laboratories. Flow cytometry (FCM) can precisely evaluate cell kinetics by measuring the DNA content of stained nuclei. We tested a new ready-to-use kit for the blastogenic response of mitogen stimulated lymphocytes in FCM for clinical immunological screening (Blastest, Ylem). Separated peripheral blood lymphocytes from the same donors were also tested with the 3H-TdR method at 72h and results compared to FCM. Our results show a significant correlation between data obtained from FCM and 3H-TdR method. We show that there are no differences in results between different cytometers if CVs are low. Flow cytometry is more precise and reproducible and makes a better standardization feasible, it also offers a simpler and faster way for routine LTT enabling a wider clinical use.