However, the combination of inhibitors against two receptors showed no increased cytotoxicity compared to that of one alone (77). criteria for CIK expansion. incubation with an anti-CD3 antibody, interferon- (IFN-), and interleukin (IL)-2. They can kill Lannaconitine tumor cells mediated by FasL and perforin (17). According to the presence of cell surface molecule CD56, CIK cells are also divided into two main subsets: CD3+CD56+ T cells and CD3+CD56? T cells (18). CD3+CD56+ T cells, which are also called the natural killer T cells, are considered to be the major effector cells of CIK. So, CIK cells can lyse cancer cells in a MHC-unrestricted manner through activating NK cell receptors such as DNAX accessory molecule-1, NKp46, NKG2D, and NKp30 (11, 19, 20). In addition to the direct killing effect of CIK on cancer cells, they can also regulate the immune function by secreting various cytokines. A lot of studies have indicated that after stimulation by tumor Lannaconitine cells, the levels of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-, IFN-, and IL-2 secreted by CIK cells are significantly upregulated (21), and these cytokines further enhance systemic antitumor activity and induce a Th1 immune response. Expansion and Alloreactivity of CIK Cells Obtaining a sufficient number of antitumor immune cells is a critical step in the successful application of CIK cell immunotherapy (22). Fortunately, CIK cells can be easily expanded from peripheral blood mononuclear cells (PBMC), and some reports also showed that they could be also generated from umbilical cord blood precursors or bone marrow (23, 24). The general culture protocol for the expansion of CIK cells requires 3C4?weeks with the addition of IFN-, anti-CD3 Rabbit Polyclonal to PKR1 antibody, and IL-2. And the detail steps are as follows: on day 0, the PBMC are separated by density-gradient centrifugation from the whole blood (24, 25) and treated with IFN- to activate macrophages, which further provide cytokine-mediated (IL-12) and contact-dependent (CD58/LFA-3) signals to promote the cytotoxic power of CIK cells (26C28). On day 1, anti-CD3 antibody and IL-2 are added to the medium. Anti-CD3 will provide mitogenic signals for T cells which are then sustained by the continuous presence of IL-2 (29, 30). Fresh medium with IL-2 is added every 2?days. After 3C4?weeks of culture, the generated CIK cells are subsequently infused back into patients (Figure ?(Figure2).2). The amount of injected CIK cells varied in different studies, so did the cell expansion rates. In fact, the average final expansion rates were usually in a range of 100-fold, but individual expansion rate was described to be variable from few Lannaconitine to more than 1,000-fold (5, 25, 31, 32). It is well known that the more the CIK cells are injected and expanded, the better they response. Hontscha et al. showed that the total number of injected CIK cells ranged from 21.9??107 to 5.2??1010 (14), Li et al. found the total number of CIK cells ranged from 6??106 to 1 1.5??1010 in Chinese clinical trials (33). Until now, the least injected number of CIK cells was reported to be 6??106 to obtain an objective response. Cohen et al. considered that tumor-infiltrating lymphocytes (TILs) must be expanded to 1010 for a successful treatment (34). Therefore, ~1010 CIK cells might be a good choice and many studies used more than 1??1010 cells to transfuse into the patients. As mentioned above, the reason why CIK expansion rate varies greatly is unclear. But there are still some additional strategies under investigation to further improve the expansion of CIK cells (22), which include adding new cytokines to the culture medium, such as IL-1, IL-7, IL-15, or thymoglobulin (8, 35, 36). Open in a separate window Figure 2 expansion of cytokine-induced killer cells and infusion. Cytokine-induced killer immunotherapy, a personalized therapy that uses patients own PBMC to expand antitumor CIK cells which are then reinjected into patients themselves, rarely causes autoimmune response. But sometimes, it is very difficult to obtain a sufficient number of CIK cells due to the poor health situation of patients, such as elderly people and patients with immunodeficiency diseases (37). To solve this problem, getting CIK cells from donor PBMC seems to be an alternative option. Studies showed that CIK cells exhibited a decreased alloreactivity across HLA barriers that could further reduce the risk of graft-versus-host disease (GVHD). Many phase I clinical studies proved that infusion of the allogeneic CIK cells in patients relapsing after allogeneic hematopoietic cell transplant would reduce the incidence of GVHD events (38C40). Another solution to obtain sufficient CIK cells is collecting from the cord.