Brain, behavior, and immunity
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Brain Behav. Immun. · Sep 1994
The role of LGL/NK cells in surgery-induced promotion of metastasis and its attenuation by morphine.
Painful stress such as surgery has been shown both to suppress immune function and to promote metastasis, although the degree to which alterations in immunity underlies the tumor-enhancing effects of surgery remains unclear. We recently reported that an experimental laparotomy results in a twofold increase in the number of lung metastases following iv injection of MADB106 tumor cells, a natural killer (NK)-sensitive mammary adenocarcinoma cell line, syngeneic to the Fischer 344 rats we studied. Further, the administration of an analgesic dose of morphine prevented these metastatic-enhancing effects of surgery. ⋯ In the LGL/NK-depleted animals, however, although the tumor-enhancing effects of surgery remained evident, morphine did not mitigate this outcome. These results suggest that: (a) both LGL/NK cell activity and other factors independent of LGL/NK cells play a role in the surgery-induced increase in tumor cell retention; and (b) LGL/NK cells play a critical role in morphine's attenuating effects on this outcome. Finally, these results reinforce concern about the pathogenic consequences of unrelieved pain.