Abstract
Background As cellular immunotherapy with ex vivo expanded cells becomes more widely used to treat a variety of illnesses, optimization of culture parameters, to maximize cell production and function, is essential for continued success. The effects of reduced oxygen tension and autologous plasma on T-cell expansion, receptor expression, apoptosis, and cytolytic activity in serum-free media were investigated. Methods PBMCs derived from whole blood samples were activated with anti-CD3 and anti-CD28 MAb in serum-free (AIM V) medium containing IL-2, and maintained at 5% and 20% oxygen tension. In some cases cultures were supplemented with 2% autologous plasma. Results Low oxygen enhanced T-cell expansion 13- and 4.8-fold in serum-free and plasma-supplemented media, respectively. Autologous plasma also had a beneficial effect on T-cell cultures. Plasma-supplemented cultures expanded 74-fold more than serum-free cultures at low oxygen tension, and 43-fold more at high oxygen tension. Several samples expanded very poorly under serum-free conditions, and reasonable cell numbers were obtained only from plasma-supplemented cultures. CD49d expression density increased 3-fold to 4-fold in cultures supplemented with plasma. In contrast to our previous findings in serum-containing media, IL-2 receptor expression kinetics were unaffected by oxygen tension. No effects caused by oxygen tension or autologous plasma on expression of other surface antigens (CD4, CD8, CD44, CD95) were observed. Discussion Low oxygen tension and autologous plasma greatly increase expansion of T cells, thereby decreasing the time needed for production of cells for prophylaxis. Increased CD49d expression density may translate into improved migration and cytotoxicity.