Comparison of Three CD3-Specific Separation Methods Leading to Labeled and Label-Free T Cells.

T cells are an essential part of the immune system. They determine the specificity of the immune response to foreign substances and, thus, help to protect the body from infections and cancer. Recently, T cells have gained much attention as promising tools in adoptive T cell transfer for cancer treatment. However, it is crucial not only for medical purposes but also for research to obtain T cells in large quantities, of high purity and functionality. To fulfill these criteria, efficient and robust isolation methods are needed. We used three different isolation methods to separate CD3-specific T cells from leukocyte concentrates (buffy coats) and Ficoll purified PBMCs. To catch the target cells, the Traceless Affinity Cell Selection (TACS®) method, based on immune affinity chromatography, uses CD-specific low affinity Fab-fragments; while the classical Magnetic Activated Cell Sorting (MACS®) method relies on magnetic beads coated with specific high affinity monoclonal antibodies. The REAlease® system also works with magnetic beads but, in contrast to MACS®, low-affinity antibody fragments are used. The target cells separated by TACS® and REAlease® are "label-free", while cells isolated by MACS® still carry the cell specific label. The time required to isolate T cells from buffy coat by TACS® and MACS® amounted to 90 min and 50 min, respectively, while it took 150 min to isolate T cells from PBMCs by TACS® and 110 min by REAlease®. All methods used are well suited to obtain T cells in large quantities of high viability (>92%) and purity (>98%). Only the median CD4:CD8 ratio of approximately 6.8 after REAlease® separation differed greatly from the physiological conditions. MACS® separation was found to induce proliferation and cytokine secretion. However, independent of the isolation methods used, stimulation of T cells by anti CD3/CD28 resulted in similar rates of proliferation and cytokine production, verifying the functional activity of the isolated cells.

A comparative study of two separation methods to isolate monocytes.

Separation of specific blood cells is necessary for a deeper insight into their role in health and disease. To obtain such cells, efficient and robust isolation methods are needed. We compare here the Fab-based Traceless Affinity Cell Selection (TACS®) technology and the Magnetic Activated Cell Sorting (MACS®) technology to isolate human monocytes from whole blood and buffy coats as well as the differentiation of the isolated monocytes to dendritic cells (DCs). TACS® is a positive selection technology using immune affinity chromatography based on CD-specific low affinity Fab-fragments for the reversible capture and release of target cells. The positive selection by MACS® is based on magnetic beads coated with specific high affinity monoclonal antibodies to catch the target cells. The target cells separated by TACS® are "label-free" while cells positively isolated by MACS® will carry the cell specific label. Our data show that the separation methods described here are well suited to obtain functional monocytes of high quality and purity. A differentiation of the cells into DCs leads to comparable results with the exception that CD1a expression levels on immature and mature DCs are elevated when monocytes are isolated using the TACS® technology. Taken together, our results suggest that the TACS® method may be of advantage when preparing monocytes and monocyte-derived DCs for functional analyses, while the MACS® method seems to be capable of higher monocyte recoveries. © 2018 International Society for Advancement of Cytometry.