Lymphoid cell populations in splenectomized and nonsplenectomized SJL/J mice bearing Hodgkin's disease-like reticulum cell sarcoma

Splenectomy suppresses growth and metastasis of hepatocellular carcinoma through decreasing myeloid-derived suppressor cells in vivo

The function of the spleen in tumor development has been investigated for years. The relationship of the spleen with hepatocellular carcinoma (HCC), a huge health burden worldwide, however, remains unknown. The present study aimed to examine the effect of splenectomy on the development of HCC and the possible mechanism. Mouse hepatic carcinoma lines H22 and Hepa1-6 as well as BALB/c and C57 mice were used to establish orthotopic and metastatic mouse models of liver cancer. Mice were divided into four groups, including control group, splenectomy control group (S group), tumor group (T group) and tumor plus splenectomy group (T+S group). Tumor growth, metastases and overall survival were assessed at determined time points. Meanwhile, myeloid-derived suppressor cells (MDSCs) were isolated from the peripheral blood (PB), the spleen and liver tumors, and then measured by flow cytometery. It was found that liver cancer led to splenomegaly, and increased the percentage of MDSCs in the PB and spleen in the mouse models. Splenectomy inhibited the growth and progression of liver cancer and prolonged the overall survival time of orthotopic and metastatic models, which was accompanied by decreased proportion of MDSCs in the PB and tumors of liver cancer-bearing mouse. It was suggested that splenectomy could be considered an adjuvant therapy to treat liver cancer.

Decreased Growth Rate of Lung Metastatic Lesions after Splenectomy in Mice

BACKGROUND

The effect of splenectomy on hematogenous metastases of malignant tumors remains controversial. The aim of this study was to clarify the effect of splenectomy on hematogenous metastases in an animal model.

METHODS

Colon 26 cancer cells were inoculated into the lateral tail vein of 90 mice. The mice were then assigned to a splenectomy group or a control group. Lung weight, number of lung metastases, size of metastatic nodules, and serum vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) levels after the surgical procedure were measured and compared between the two groups.

RESULTS

The lung nodules were significantly smaller in the splenectomy group than in the control group. In both groups, the serum VEGF levels increased on day 1 and then decreased. The serum VEGF levels on day 5 were significantly lower in the splenectomy group than in the control group. The serum bFGF levels were significantly lower in the splenectomy group than in the control group on days 1 and 5. Immunohistochemical study showed that bFGF was produced by reticuloendothelial cells of the spleen.

CONCLUSION

The growth rate of hematogenous metastatic lesions appears to decrease after splenectomy and may be associated with decreases in serum levels of VEGF and bFGF induced by splenectomy.

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)

Changes of peripheral T-cell subsets in asplenic W256 tumor-bearing rats

In exploring the mechanism of the effect of splenectomy on tumor growth, splenectomized rats and other control rats were implanted subcutaneously with Walker 256 carcinosarcoma cells (5 x 10(5] on day 10 after splenic operation; meanwhile, peripheral T-lymphocyte subsets were analysed successively. It was found that splenectomy enhanced the rate of tumor appearance and mean tumor diameter and disturbed the equation of T-lymphocyte subsets in peripheral blood, i.e., a subnormal level of Th/Ts ratio. Interestingly, a significant correlation was noted between decreasing values of Th/Ts ratio and increasing average diameters of implanted tumor in splenectomized rats, but not in sham-splenectomized or nonoperated rats with tumor growth. In spleen cells from tumor-bearing rats, a distinct increase of B-lymphocytes and a decrease of T cells were demonstrated. Data from this investigation provide striking evidence that a relationship exists between enhancement of tumor growth and disproportion of T-lymphocyte subsets in peripheral blood and offer some reasonable explanation for the causes of the promotive role of tumor growth following splenectomy.

The importance of splenectomy for the adoptive immunotherapy of cancer

Adoptive immunotherapy (AIT) of cancer using lymphocytes cultured in vitro in interleukin-2 (LAK cells) has gained much attention due to the high level of broad anti-tumor activity both in vitro and in vivo. A major hypothesis has suggested that if unfractionated lymphoid cells grown in IL-2 can mediate significant anti-tumor effects then purified LAK effector cells should yield even higher activity. Furthermore, devising new techniques to achieve optimal expansion of the purified LAK effector cells would further improve this form of immunotherapy. In this report we present data on a new method for purifying and expanding LAK effector cells obtained from the peripheral blood and spleen. The results indicate that as a source of LAK cells, the spleen is superior both quantitatively ani qualitatively when compared to peripheral blood and should be seriously considered as the source of cells for AIT of cancer.