Bovine apolipoprotein B-100 is a dominant immunogen in therapeutic cell populations cultured in FCS in mice and humans

Authors: SAKAMOTO, NORIHISA - US FDA; TSUJI, KAZUHIDE - US FDA; MUUL, LINDA - NHGRI, NIH; LAWLER, ANN - JOHNS HOPKINS UNIV.; PETRICOIN, EMANUEL - GEORGE MASON UNIV; CANDOTTI, FABIO - NHGRI, NIH; METCALF, JULIA - NIAID, NIH; TAVEL, JORGE - NIAID, NIH; LANE, H. CLIFFORD - NIAID, NIH; URBA, WALTER - PROVIDENCE PORTLAND MC; FOX, BERNARD - PROVIDENCE PORTLAND MC; VARKI, AJIT - UNIV OF CA; Lunney, Joan; ROSENBERG, AMY - US FDA

Submitted to: Blood
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2007
Publication Date: 7/15/2007
Citation: Sakamoto, N., Tsuji, K., Muul, L.M., Lawler, A.M., Petricoin, E.F., Candotti, F., Metcalf, J.A., Tavel, J.A., Lane, H., Urba, W.J., Fox, B.A., Varki, A., Lunney, J.K., Rosenberg, A.S. 2007. Bovine apolipoprotein B-100 is a dominant immunogen in therapeutic cell populations cultured in FCS in mice and humans. Blood. 110:501-508.

Interpretive Summary: Scientists who develop embryonic stem (ES) cells need to grow them under very controlled conditions, otherwise unintended immune reactions can result from stem cell injection during immunotherapy. Thus, studies must be performed in model systems to prescreen for problems; for this report the mouse was the model. The studies reported here have demonstrated that murine ES cell populations cultured in heterologous animal (bovine) products can acquire some of those animal proteins, which are then termed as xenoantigens. Such xenoantigens would limit the utility of the ES cell infusion. In investigations of the immune response to murine ES cells, we found that a strong antibody response was generated after the second infusion, producing polyclonal antibodies, and monoclonal antibody responses derived from infused mice. This paper proves that the antibodies were specific for bovine apolipoprotein B-100 which binds to abundant low density lipoprotein receptor on the murine ES cell surface and is internalized. To prove the importance of the development of these anti-bovine apolipoprotein B-100 responses clinical samples from human patients were evaluated. Those studies showed that in the majority of patients administered any of three different types of cell-based therapies utilizing ES cells grown in bovine calf serum containing media, developed an antibody response to bovine apoB-100 following the second infusion. Notably this anti-bovine apolipoprotein B-100 was the dominant specificity. This response may account for the low level of engraftment of genetically modified autologous cells in certain patients and suggests that such antibodies may influence ES cell engraftment. The recent switch to human AB serum-based medium as a substitute for fetal calf serum is important for future ES studies. Alternately, use of autologous (patient’s own) serum may be the most prudent and safe means for culturing ES or other therapeutic cell populations prior to transplantation.

Technical Abstract: Recent studies have demonstrated that cell populations intended for therapeutic purposes that are cultured in heterologous animal products can acquire xenoantigens, potentially limiting their utility. In investigations of the immune response to murine ES cells, we found that a strong antibody response was generated after the second infusion. Both polyclonal and monoclonal antibody responses, derived from immunized mice, were found to be specific for bovine apolipoprotein B-100 which binds to abundant low density lipoprotein receptor on the cell surface and is internalized. Critically, we have shown that in the majority of patients administered three different types of cell-based therapies utilizing cells grown in FCS containing media, an antibody response to bovine apoB-100 develops following the second infusion and is the dominant specificity. The low level of engraftment of genetically modified autologous cells in an ADA-SCID patient with a strong bovine apoB response suggests that such antibodies may influence cell engraftment.