t. injection of DC. Large numbers of CD45.2+-injected DC were detected in the tumours on day 1; however, the percentage of CD45.2+ DC within the total CD11c+ DC population in the tumours from the fully allogeneic ITADT group was relatively low compared with those in the tumours from the syngeneic or semi-allogeneic ITADT groups (Fig. 3). On day 2, the percentages of CD45.2+ DC were decreased, but a small (but clear) population of CD45.2+ DC was detected in the tumours from the syngeneic and semi-allogeneic ITADT groups. Notably, no CD45.2+ DC were detected in the tumours from the fully allogeneic ITADT group (Fig. 3). In the

draining lymph nodes, subtle numbers of CD45.2+ DC were detected on day 1 after the second i.t. injection of DC, but there was no significant difference in the percentages of CD45.2+ DC within the total CD11c+ 5-Fluoracil manufacturer DC population between the different groups (data not shown). On day 2 after the second i.t. injection of DC, no CD45.2+ DC were detected in the lymph nodes from any of the ITADT-treated mice (data not shown). In addition,

no CD45.2+ DC were detected in the spleens in any of the ITADT groups on day 1 or day 2 (data not shown). These findings suggest that injected DC tend to remain at the tumour site, and the survival time of i.t.-injected semi-allogeneic DC is relatively longer than that Bortezomib cell line of fully allogeneic DC in the setting of ITADT, even when the semi-allogeneic DC express the same alloantigens as fully allogeneic DC. As mentioned previously, three factors may affect the efficiency of an allogeneic DC-driven antitumour

response when used for immunotherapy: (1) the short survival time of allogeneic DC because of T-cell-mediated rejection; (2) MHC compatibility with the host cells in the context of antigen presentation and (3) the role of host-derived pAPC. To elucidate which of the factors affect the antitumour responses heptaminol of allogeneic DC, and to what degree, we conducted an experiment using recipient mice transplanted with allogeneic BMC, where the three factors can be individually assessed as the following features (summarized in Table 1): (1) B/c recipients of fully allogeneic (BL6 B/c) and mixed (BL6+ B/c B/c) BMC were rendered immunologically tolerant to the BL6 alloantigens [25, 28, 29, 33], and the recipients could not reject the injected allogeneic BL6 DC. On the other hand, the recipients of syngeneic BMC (B/c B/c) were able to reject the injected BL6 DC; (2) all recipients were B/c, in which cTECs express only H-2d. Therefore, the T cells in all recipients were H-2d restricted, so B/c DC, but not BL6 DC, could function as pAPC; (3) because the tumour-associated pAPC population in recipients of both syngeneic (B/c B/c) and mixed (B/c + BL6 B/c) BMC contained H-2d-positive cells at the time of ITADT, they could function as pAPC.