Group O plasma as a media supplement for CAR‐T cells and other adoptive T‐cell therapies

BACKGROUND Most chimeric antigen receptor T (CAR‐T) cells and other adoptive T‐cell therapies (ACTs) are currently manufactured by ex vivo expansion of patient lymphocytes in culture media supplemented with human plasma from group AB donors. As lymphocytes do not express A or B antigens, the isoagglutinins of non‐AB plasmas are unlikely to cause deleterious effects on lymphocytes in culture. STUDY DESIGN AND METHODS Seeding cultures with peripheral blood mononuclear cell (PBMNC) concentrates from group A 1 donors and using a CAR‐T culture protocol, parallel cultures were performed, each with unique donor plasmas as media supplements (including group O plasmas with high‐titer anti‐A and group AB plasmas as control). An additional variable, a 3% group A 1 red blood cell (RBC) spike, was added to simulate a RBC‐contaminated PBMNC collection. Cultures were monitored by cell count, viability, flow cytometric phenotype, gene expression analysis, and supernatant chemokine analysis. RESULTS There was no difference in lymphocyte expansion or phenotype when cultured with AB plasma or O plasma with high‐titer anti‐A. Compared to controls, the presence of contaminating RBCs in lymphocyte culture led to poor lymphocyte expansion and a less desirable phenotype—irrespective of the isoagglutinin titer of the plasma supplement used. CONCLUSIONS This study suggests that ABO incompatible plasma may be used as a media supplement when culturing cell types that do not express ABO antigens—such as lymphocytes for CAR‐T or other ACT. The presence of contaminating RBCs in culture was disadvantageous independent of isoagglutinin titer.