Strategies using epitope-based vaccination are being considered for melanoma immunotherapy, in an attempt to overcome failure of other modalities. In the present study, we designed and produced a multiepitope polypeptide for melanoma (MEP-mel), which contains three repeats of four antigenic epitopes (gp100:209-217 (210M); gp100:280-288 (288V); Mart1:26-35 (27L); tyrosinase: 368-376 (370D). The peptides were attached to each other by linkers containing sequences recognized by the proteasome, to improve protein cleavage and antigen presentation. The results show that peptidespecific T cells produced IFN-γ when stimulated with MEP-mel-transfected dendritic cells. The presentation of peptides by MEP-mel-transfected dendritic cells was proteasome-dependent and was more long-lasting than the presentation of exogenously delivered native peptides. When dendritic cells were loaded with MEP-mel protein, weak cross presentation was induced. The production of multiepitope molecules based on several peptides linked by sequences sensitive to proteasomal cleavage represents a promising new tool for the improvement of cancer immunotherapy.

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The thymus is a primary lymphoid organ responsible for the maturation of T cells as well as the immunological central tolerance. It is in the antenatal period and infancy that it plays its major role. In clinical practice, T cell receptor excision circles (TRECs) are considered a direct and reliable measure of the thymic function. TRECs are a by-product of DNA formation in gene rearrangement of T cell receptors. They are stable and they do not duplicate during mitosis, representing the recent emigrant T cells from the thymus. Despite their importance, TRECs have been neglected by physicians and there is a lack of data regarding thymic function during infancy of healthy children. In order to evaluate thymic function in the first years of life, we propose measuring TRECs as a valuable tool. One hundred and three blood samples from children and adolescents between 3 months and 20 years of age were analyzed. The mean TRECs count was 136.77±96.7 copies of TRECs/μL of DNA. The individuals between 0 and 5 years of age had significantly higher TRECs values than those between 10 and 20 years of age. No significant difference was observed in TRECs values among age groups below 5 years of age. An inverse correlation between TRECs and age was found (r=0.3 P=0.003). These data highlight and validate the evidence of decreased thymus function with age, even during infancy. Awareness should be raised with this important albeit ignored organ.

SUMMARYThe effects of nutrients on the mucosal immune system are poorly understood. The aim of this work was to study the cellular mucosal immune response to intrajejunal perfusion of an elemental diet (ED) or a control (C) electrolyte solution by measuring jejunal secretion of soluble CD4 (sCD4) and sCD8. sCD4 and sCD8 are markers of helper/inducer and suppressor/cytotoxic regulatory functions of T cells, respectively. A four lumen tube with a proximal occluding balloon at the angle of Treitz was used for jejunal perfusion in seven healthy volunteers (mean age 23 years). The length of the test segment was 40 cm. The jejunum was successively perfused with C for 80 min and then with ED containing 21 . 3 g/l of free amino acids and 104 . 2 g/l of oligosaccharides for 100 min. Jejunal fluid and serum concentrations of sCD4 and sCD8 were measured and their jejunal outputs calculated. When compared with C perfusion, jejunal perfusion with the ED resulted in a significant increase of sCD8 but not sCD4 jejunal secretion rates. sCD8 jejunal values increased early after ED perfusion and stayed at roughly the same level during the perfusion. Serum concentrations of sCD4 and sCD8 were not modified during ED perfusion. These data support the hypothesis that ED suppresses the immunologic tone of the gut, which could explain its beneficial effect in the management of intestinal inflammatory disease.