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Background and Objectives: Glutamine (gln), a non-essential amino acid, has recently received increasing attention because it becomes essential during stress and catabolic states: glutamine seems to modulate immune function and to promote faster intestinal healing after chemotherapy. We designed two consecutive randomized clinical trials to evaluate the role of glutamine-enriched parenteral nutrition (GEPN) in patients with hematologic malignancies submitted to high dose chemotherapy and autologous peripheral blood stem cell transplantation (aPBSCT) or immunoselected CD34+ aPBSCT., Design and Methods: In study1, the Gln group (12 patients) received total parenteral nutrition (TPN) enriched with glutamine 20 g from day +1 after aPBSCT, while the placebo group (15 patients) received TPN lacking in glutamine (placebo). In study2, the Gln group (10 patients) received TPN enriched with glutamine 13.46 g from day +1, while the placebo group (11 patients) received a placebo., Results: In the first study, a lymphocyte count >0.5 109/L was achieved on day 16.5 in the Gln group and on day 29 in the placebo group (p=0.005); in the second study, the lymphocyte count >0.5 109/L was achieved on day 18 in the Gln group and on day 29 in the placebo group (p=0.009). Lymphocyte subset analysis showed an increase of CD3+ and CD4+ and normalization of the CD16+CD56+ subset. Furthermore patients receiving GEPN showed a decrease in the mucositis severity peak calculated by the DMS (daily mucositis score: sum of the daily score of signs and symptoms) (p=0.047)., Interpretation and Conclusions: GEPN is safe and effective and improves lymphocyte recovery after aPBSCT; further studies are needed to assess the clinical benefits of such an approach in order to justify its economic impact.

Granulocyte colony-stimulating factor (G-CSF) may affect T-cell homeostasis by multiple mechanisms, inducing polarization of cytokine secretion, inhibition of T-cell proliferation, and enhancement of T-cell apoptosis. We analyzed the production of interleukin-10 (IL-10) and transforming growth factor-beta1 (TGF-beta1) by T cells from healthy volunteer donors treated with recombinant human G-CSF. Highly purified CD4(+) T cells obtained before and after G-CSF administration (pre-G and post-G, respectively) were activated using the allogeneic mixed leukocyte reaction. Post-G CD4(+) T cells produced high levels of IL-10 but undetectable levels of IL-2 and IL-4, whereas the level of TGF-beta1 release was comparable to that of pre-G CD4(+) T cells. Notably, post-G CD4(+) T cells proliferated poorly in response to alloantigens and to recall antigens and suppressed the proliferation of autologous CD4(+) T cells in a cell contact-independent and an antigen-nonspecific manner. TGF-beta1 and IL-10 were not dispensable for post-G CD4(+) T cells to mediate suppression, as shown by neutralization studies. Compared with pre-G CD4(+) T cells, alloantigen-activated post-G CD4(+) T cells preferentially expressed markers associated with memory T cells, in conjunction with reduced levels of CD28 and CD62L. Collectively, these data demonstrate that CD4(+) T cells exposed to G-CSF in vivo acquire the properties of T regulatory (Tr) cells once triggered in vitro through the T-cell receptor, including a peculiar cytokine production profile (IL-10(++)TGF-beta1(+)IL-2(low/-)IL-4(low/-)), an intrinsic low proliferative capacity, and a contact-independent suppression of antigen-driven proliferation. Tr cells generated ex vivo after exposure to G-CSF might be clinically relevant for transplantation medicine and for the treatment of human immune-mediated diseases.