Abstract
4693
It remains unclear what in vitro properties of anti-CD3 activated L-selectin(low) effector T cells (TE) correlate best to their superior therapeutic potency in mice. Because substituting mouse serum (MS) for FCS in culture medium (CM) signficantly enhanced therapeutic potency, we performed comparative co-analyses of immunophenotypic markers, intracellular cytokine production, V-beta TCR repertoires, and Annexin-V binding in vitro, to determine which TE characteristics were distinctively modulated by CM-MS prior to adoptive transfer. In vitro anti-CD3 activation constituted a truly polyclonal stimulus, yet an enhanced proliferative response was observed within the tumor-primed subpopulation, favoring its preferential expansion during the first 2 weeks of culture in either CM-FCS or CM-MS. Despite CM-MS’s enhancement of therapeutic potency, the content of tumor-specific, IFN-gamma producing TE and their V-beta repertoires remained similar in either CM-MS or CM-FCS, and TE activated under either condition displayed comparable trafficking following adoptive transfer. However, TE propagated in CM-MS displayed lower prospective susceptibility to apoptosis, with or even without TCR reengagement. MS as well as human serum contained assayable anti-apoptotic activity which was distinct from effects of rIL-7, rIL-15 or FAS ligand neutralization. We conclude: (1) initial anti-CD3 stimulation of in vivo tumor-primed T cells leads to their natural enrichment in culture; (2) seemingly minor culture modification can preserve or even improve therapeutic potency without detectably altering TE repertoire, trafficking or tumor-specific TE content; (3) in vitro resistance to apoptosis positively correlates to improved therapeutic potency in vivo; (4) sera themselves can confer distinctive anti-apoptotic activity to cultures and can dominate therapeutic outcome.
[Proc Amer Assoc Cancer Res, Volume 45, 2004]
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