Comparison of anti-CD3 and anti-CD28-coated beads with soluble anti-CD3 for expanding human T cells: differing impact on CD8 T cell phenotype and responsiveness to restimulation

The ability to expand virus- or tumor-specific T cells without damaging their functional capabilities is critical for success adoptive transfer immunotherapy of patients with opportunistic infection or tumor. Careful comparisons can help identify expansion

Anti-CD3/CD28 beads are highly effective for expanding CD4 cells, but soluble anti-CD3 has significant potential advantages for expanding CD8 T cells, particularly where preservation of phenotypically "young" CD8 cells would be desirable, or where the T cells of interest have been antigen-stimulated in vitro or in vivo in the recent past.

We compared the efficacy of magnetic beads coated with anti-CD3 and anti-CD28 (anti-CD3/CD28 beads), and soluble anti-CD3 plus mixed mononuclear cells (designated a rapid expansion protocol or REP) in expanding normal human T cells.

Both anti-CD3/CD28 beads and soluble anti-CD3 promoted extensive expansion. Beads stimulated greater CD4 cell growth (geometric mean of 56- versus 27-fold (p < 0.01) at day 21) but both stimulated similar CD8 expansion (189- versus 186-fold). Phenotypically, bead-treated CD4 and CD8 T cells and anti-CD3-treated CD4 cells typically assumed an effector/effector memory phenotype by day 14. By comparison, a subset of anti-CD3-treated CD8 cells, derived from naïve cells, retained much greater expression of CD45RA, CD27 and CCR7, than matched bead-treated cells despite comparable expansion. These cells were clearly distinguishable from CD45RA+ terminally differentiated effector cells by the presence of CD27, the absence of CD57 and their inability to produce cytokines after stimulation. When used to expand previously stimulated cells, anti-CD3 plus autologous MNCs produced much less antigen-induced cell death of CD8 cells and significantly more CD8 expansion than beads. Conclusions: Anti-CD3/CD28 beads are highly effective for expanding CD4 cells, but soluble anti-CD3 has significant potential advantages for expanding CD8 T cells, particularly where preservation of phenotypically "young" CD8 cells would be desirable, or where the T cells of interest have been antigen-stimulated in vitro or in vivo in the recent past.