Specialized immune cells known as natural killer (NKT) cells are recruited into human tumors and may help fight the cancer according to a report in The Journal of Experimental Medicine. The chemical attractant that draws in the NKT cells was also identified and may be used in the future to prevent the growth and spread of tumors.
NKT cells are important in the protective immune response to cancer in mice and can kill tumor cells directly or by activating other cell types, but evidence from human tumors has been difficult to obtain. In this study, Robert Seeger and colleagues looked at a type of childhood tumor of the nervous system (outside the brain) known as a neuroblastoma, and found that more than half of the patient tumor samples analyzed contained NKT cells.
To uncover how the NKT cells are attracted into the tumor from the blood, the authors looked at the types of attracting signal (known as chemokines) that the tumour produces. One particular attractant (the chemokine CCL2), which can specifically attract NKT cells, was produced in large amounts by some tumors. Tumors that produced the most CCL2 contained the most NKT cells.
Patients with tumors that contained NKT cells survived for longer than patients with tumors without NKT cells. Also, neuroblastomas with abnormally high levels of the cancer-causing gene MYCN, which is associated with worse disease, produced small amounts of CCL2 and contained few NKT cells. These findings indicate that it might be possible to manipulate tumors to favor NKT-cell immune responses by targeting MYCN and/or CCL2.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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