Abstract
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 MADB 106 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. The aim of the present study was to investigate the role of NK cells in both the metastatic-enhancing effects of surgery and the attenuation of these effects by morphine. Using a simple 2 × 2 experimental design (surgery with anesthesia vs anesthesia only, and morphine vs vehicle), we found that surgery resulted in a decrease in both whole blood NK cytotoxic activity and number of circulating LGL/NK cells assessed 4 h postoperatively. In a second experiment involving an 18-h lung clearance assay, we used the mAb 3.2.3 to deplete rats of LGL/NK cells with the following rationale: if LGL/NK cells are necessary to mediate an event, then in their absence, that event should not occur. Normal and LGL/NK-depleted animals were assigned to the same four experimental groups, and radiolabeled MADB 106 tumor cells were injected iv 4 h after surgery. In normal animals, there was a significant interaction between surgery and morphine such that morphine attenuated the surgery-induced increase in tumor cell retention without affecting tumor cell retention in the anesthesia groups. 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.
Original language | English (US) |
---|---|
Pages (from-to) | 241-250 |
Number of pages | 10 |
Journal | Brain Behavior and Immunity |
Volume | 8 |
Issue number | 3 |
DOIs | |
State | Published - Sep 1994 |
Externally published | Yes |
ASJC Scopus subject areas
- Immunology
- Endocrine and Autonomic Systems
- Behavioral Neuroscience