Effect of splenectomy upon the growth of B16-F10 melanoma and its relation to the interferon system

Alcohol consumption suppresses metastasis of B16-BL6 melanoma in mice

Female C57BL/6 mice were fed a defined, pelleted diet and given 10% w/v or 20% w/v ethanol in their drinking water. Natural killer (NK) cell cytolytic activity was compared between water-drinking and ethanol-consuming mice and in mice that were also treated with polyinosinic-polycytidylic acid (poly I:C) to augment NK cell activity or with anti-NK1.1 antibody to decrease activity. NK cell cytolytic activity was not altered in mice given 10% ethanol, but was decreased in mice given 20% ethanol compared to water-drinking mice. Poly I:C treatment increased and anti-NK1.1 antibody treatment decreased NK cell activity in both water-drinking and 20% ethanol-consuming mice. Experimental and spontaneous metastases of B16-BL6 melanoma were evaluated as a function of the duration of ethanol consumption before tumor inoculation and as a function of altered NK cell activity. Experimental metastasis was inhibited after 4 and also after 6.5 weeks of ethanol exposure. Poly I:C treatment inhibited tumor lung colonization irrespective of ethanol consumption. Anti-NK1.1 antibody treatment increased metastasis, although to a lesser degree in mice consuming 10% ethanol. Spontaneous metastasis was inhibited in mice consuming 10% ethanol for 4 weeks, and in mice consuming 20% ethanol for 1 and 4 weeks before melanoma inoculation.

Effect of alcohol on spleen cells and their functions in C57BL/6 mice

Spleen cells from C57BL/6 mice maintained on alcohol containing liquid diet for two weeks were evaluated for different immune functions. On an average, 22% fewer spleen cells were recovered from alcohol-fed mice when compared to cells from control animals. In alcohol-fed mice, the relative frequency of B cells increased, whereas total T cells including CD4+ cells decreased significantly. Alcoholic mice, when challenged with poly(rI) poly(rC), produced significantly less interferon than control mice. In vitro production of interferon alpha and gamma by the spleen cells of alcoholic mice was reduced by 67-90%. No significant differences were seen in the level of natural killer cell activity in spleen cells of control and alcoholic mice. These results suggest that chronic alcohol intake can result in not only changes in the number of immune cells, but more importantly affect their biological functions such as their ability to produce interferons.

Effects of splenectomy on the development of tumor-specific immunity

We have previously reported on the antimetastatic effects of experimental adoptive immunotherapy using plastic adherent lymphokine-activated killer cells (A-LAK) cells (R. E. Schwarz et al. Cancer Res. 49: 1441, 1989). We have also reported that the spleen is a superior source of lymphocytes for A-LAK cell generation (R. E. Schwarz and J. C. Hiserodt, Med. Hypotheses 28: 165, 1989). This study, therefore, was designed to examine the effects of splenectomy itself on tumor growth in an experimental animal model. Natural killer (NK)-resistant MADB106 mammary adenocarcinoma cells were injected iv into F344 rats to generate multiple lung metastases. Splenectomies (Sx) were performed on Days -6, -3, -1, 0, 1, 3, 6, and 10, counted from the time of tumor injection. Groups consisted of six animals each, and sham-anesthetized and -operated animals served as controls. Splenectomies, if performed between Days -3 and +1, had significant antitumor effects as documented by the number of outgrowing surface metastases (5 +/- 7 vs greater than 300; P less than 0.0001) and by animal survival (greater than 100 vs 21 +/- 3 days; P less than 0.001). However, splenectomies, performed at an earlier or later stage, did not show these effects. Sx did not alter peripheral blood NK activity or the percentages of mononuclear cell subsets except for a slight decrease in the T-helper/T-suppressor ratio (P less than 0.04). Interleukin 2 (rhIL2), given at 2.5 X 10(5) U/kg/day for 3 days immediately after splenectomy, completely abrogated the observed antitumor effects. Subcutaneous tumor rechallenge of long-term surviving animals showed no tumor take in 87% of the animals.(ABSTRACT TRUNCATED AT 250 WORDS)