Cluster of differentiation (CD)8 ؉ T cells exist as naive, central memory, and effector memory subsets, and any of these populations can be genetically engineered into tumor-reactive effector cells for adoptive immunotherapy. However, the optimal subset from which to derive effector CD8 ؉ T cells for patient treatments is controversial and understudied. We investigated human CD8 ؉ T cells and found that naive cells were not only the most abundant subset but also the population most capable of in vitro expansion and T-cell receptor transgene expression. Despite increased expansion, naive-derived cells displayed minimal effector differentiation, a quality associated with greater efficacy after cell infusion. Similarly, the markers of terminal differentiation, killer cell lectin-like receptor G1 and CD57, were expressed at lower levels in cells of naive origin. Finally, naive-derived effector cells expressed higher CD27 and retained longer telomeres, characteristics that suggest greater proliferative potential and that have been linked to greater efficacy in clinical trials. Thus, these data suggest that naive cells resist terminal differentiation, or "exhaustion," maintain high replicative potential, and therefore may be the superior subset for use in adoptive immunotherapy. (Blood. 2011;117(3):808-814) IntroductionIt is now possible to genetically engineer human T lymphocytes to express virtually any known gene, including genes encoding T-cell receptors (TCRs) or chimeric antigen receptors (CARs), to provide the desired T-cell specificity. These gene-engineered lymphocytes hold the promise to treat infectious diseases and cancer, 1-10 but the appropriate substrate cells to use is understudied, and most current protocols simply transfer genes into "bulk" peripheral blood mononuclear cells (PBMCs). Varieties of data indicate that T cells, and in particular CD8 ϩ T cells, are worthy substrates for gene engineering. However, CD8 ϩ T cells in peripheral blood are themselves a complex mixture, composed of at least 3 major subsets-naive (T N ), central memory (T CM ), and effector memory (T EM )-each having different functional qualities.The optimal subset to engineer for adoptive immunotherapy is controversial. 8,[11][12][13][14] Memory CD8 ϩ T-cell subsets are more studied than naive cells, because antigen-specific clones can be found at increased frequencies. In a landmark paper, Berger et al 13 have shown in macaques that effector cells derived from T CM rather than T EM possess greater ability to survive and establish immunologic memory after infusion. This finding is consistent with data comparing memory subsets in mice. 15 However, T N cells were not explicitly analyzed in these reports, 12 an omission that might be important given recent findings in mice that naive T cells convey more antitumor activity than memory cells. 12 Short of conducting a series of clinical trials, the decision of which CD8 ϩ T-cell subset to use for clinical protocols will depend on the cell phenotypes that result from transduction of T...

Purpose Adoptive cell transfer (ACT) of tumor-infiltrating or genetically engineered T cells can cause durable responses in patients with metastatic cancer. Multiple clinically-modifiable parameters can comprise this therapy, including cell dose and phenotype, in vivo antigen re-stimulation, and common gamma-chain (γc) cytokine support. However, the relative contributions of each these individual components to the magnitude of the anti-tumor response have yet to be quantified. Experimental design To systematically and quantitatively appraise each of these variables, we employed the Pmel-1 mouse model treating large, established B16 melanoma tumors. In addition to cell dose and magnitude of in vivo antigen re-stimulation, we also evaluated the relative efficacy of central memory (TCM), effector memory (TEM), and stem cell memory (TSCM) subsets on the strength of tumor regression as well as the dose and type of clinically available γc cytokines, including IL-2, IL-7, IL-15, and IL-21. Results We found that cell dose, T cell differentiation status, and viral vaccine titer each were correlated strongly and significantly with the magnitude of tumor regression. Surprisingly, although the total number of IL-2 doses was correlated with tumor regression, no significant benefit to prolonged (≥6 doses) administration was observed. Moreover, the specific type and dose of γc cytokine only moderately correlated with response. Conclusions Collectively, these findings elucidate some of the key determinants of successful ACT immunotherapy for the treatment of cancer in mice and further demonstrate that γc cytokines offer a similar ability to effectively drive anti-tumor T cell function in vivo.

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Retinoic acid is required to maintain pre-DC–derived CD11b+CD8α−Esamhigh dendritic cells (DCs) in the spleen and CD11b+CD103+ DCs in the gut.

Objective-To determine the outcome of dilated cardiomyopathy presenting in childhood and the features that might, be useful for prognostic stratification.

T-cell-receptor (TCR) gene therapy enables for the rapid creation of antigen-specific T cells from mice of any strain and represents a valuable tool for pre-clinical immunotherapy studies. Here, we describe the superiority of gamma-retroviral vectors compared to lentiviral vectors for transduction of murine T cells and surprisingly illustrate robust gene-transfer into phenotypically naïve/memory-stem cell (CD62Lhi/CD44low) and central memory (CD62Lhi/CD44hi) CD8+ T cells using murine-stem-cell-based gamma-retroviral vectors (MSGV1). We created MSGV1 vectors for a MHC-class I restricted T-cell receptor (TCR) specific for the melanocyte-differentiation antigen, gp100 (MSGV1-pmel-1), and a MHC-class II restricted TCR specific for tyrosinase-related-protein-1 (MSGV1-TRP-1), and found that robust gene expression required codon optimization of TCR sequences for the pmel-1 TCR. To test for functionality, we adoptively transferred TCR-engineered T cells into mice bearing B16 melanomas and observed delayed growth of established tumors with pmel-1TCR engineered CD8+ T cells and significant tumor regression with TRP-1 TCR transduced CD4+ T cells. We simultaneously created lentiviral vectors encoding the pmel-1TCR, but found that these vectors mediated low TCR expression in murine T cells, but robust gene expression in other murine and human cell lines. These results indicate that preclinical murine models of adoptive immunotherapies are more practical using gamma-retroviral rather than lentiviral vectors.

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